The Journal of Prosthetic Dentistry

49July 2011

Pun et alPun et al

Clinical ImplicationsThe inclusive nature of this analysis helps demonstrate details of current RPD treatment that are rarely discussed in dental education or litera-ture. The lack of dentist input, use of nonmetal frameworks, bulky major connectors, and lack of adequately supported RPD designs indicates the potential for poor RPD outcomes in this sample.

Statement of problem. Current demographic information on the number and types of removable partial dentures is lacking in the prosthodontic literature.

Purpose. This study was designed to investigate patterns of tooth loss in patients receiving removable partial dentures (RPDs) in eastern Wisconsin.

Material and methods. Digital images (1502) of casts at 5 dental laboratories in eastern Wisconsin were collected. Any prescription requesting fabrication of a removable partial denture was photographed twice. The first photograph was made immediately upon arrival at the laboratory, while the second photograph was made immediately before being returned to the prescribing dentist for the first time. A calibrated investigator analyzed all the photographs for Kennedy Classification, type of RPD, major connector, and other details. Data were analyzed with descriptive statis-tics. Fisher’s exact test was used to confirm repeatability.

Results. Kennedy Class I was the most common RPD with a frequency of 38.4%. More than 40% of prescriptions had no design input from the dentist. One in 3 RPDs used acrylic resin or flexible frameworks. One in 5 RPDs had no rests. The horseshoe major connector was the most common maxillary major connector, while the lingual plate was the most common in the mandible.

Conclusions. RPDs remain a common prosthodontic treatment in this region. Non-metal RPD frameworks are a com-mon treatment type and rarely include rests. These data indicate a changing partially edentulous patient population and a variable commitment to standard levels of prosthodontic care. (J Prosthet Dent 2011;106:48-56)

Survey of partial removable dental prosthesis (partial RDP) types in a distinct patient population

Deo K. Pun, DMD, MS,a Michael P. Waliszewski, DDS, MsD,b Kenneth J. Waliszewski, DDS, MS,c and David Berzins, PhDd

Marquette University, Milwaukee, Wis

aPrivate practice, Sterling, Ill.bAdjunct Assistant Professor, School of Dentistry.cAdjunct Professor, School of Dentistry.dAssociate Professor and Graduate Program Director, Dental Biomaterials.

Recent investigations analyzed trends in demand for prosthodon-tics in the United States.1,2 More than 95 years ago Hillyer3 noted that as the edentulous condition decreases, the use of removable partial dentures (RPDs) increases. Despite decreas-ing rates of tooth loss, the need for removable prosthodontic treatment remains high.4-6 One consequence

of the profession’s improved preven-tive measures has been an increase in the number of patients who require prosthodontic treatment with RPDs.7-9 Conservative treatment types such as dental implants are expensive. This may limit their availability to lower socioeconomic groups in whom the highest rates of tooth loss occur.10-12 Conventional removable prosthodon-

tic treatment types, therefore, con-tinue to outnumber implant tooth replacements in general practice.13

Multiple RPD classification sys-tems have been proposed.14-20 The Kennedy Classification system is cur-rently the system described in 2 RPD textbooks,21,22 and was found to be the most commonly used system ac-cording to an older analysis.19 This

system also meets criteria of the prin-ciples, concepts, and practices in prosthodontics (PCPP).23

Several attempts to analyze spe-cific trends in the frequency of various RPDs have been presented.24-39 Most of these studies are of European or middle-eastern populations with few studies from the United States.6,40-43

Curtis et al42 surveyed the inci-dence of various classes of RPDs fab-ricated at a single dental laboratory in California. Interim RPDs were ex-cluded, leaving 327 of the 400 work authorizations for inclusion. Forty percent of these RPDs were Kennedy Class I, while 33% were Class II, 18% Class III, and 9% Class IV. The most common mandibular RPD was Class I (49%), and the most common maxil-lary RPD was Class II (38%). Using 5 commercial dental laboratories from different regions of North America, Öwall and Taylor43 investigated the frequency of different types of RPDs. While information regarding number and distribution of teeth was pre-sented, there was no classification. Ninety-five percent of 1,363 RPDs analyzed had cast metal frameworks. Redford’s group found that 8% of the 7,374 examined subjects were using an RPD.6 The prevalence increased with age to 22% at 55 to 64 years old. This finding did not include acrylic resin framework RPDs. In the United States, no recent analysis of incidence or prevalence of types of RPDs or Kennedy Classification was identified.

The previously mentioned studies evaluated data pertaining only to cast metal framework RPDs. This may not reflect the demographics of the aver-age clinical practice. While valid long-term outcome data is lacking, acrylic resin framework RPDs continue to be used with great frequency.44,45 Acrylic resin framework RPDs are far more common than cast metal framework RPDs in several other countries.46-50 As a group, these surveys demonstrated significant differences in patient treat-ment among institutions, government subsidized clinics, and private prac-tice. Insurance reimbursement, capa-

bilities of dental laboratory support, education, and location and extent of missing teeth all appear to influ-ence whether a cast metal framework or acrylic resin RPD is fabricated.49

In addition, newer types of flexible RPDs have received much attention in dental advertisements over the past decade. However, no peer-reviewed study or incidence data for these dif-ferent RPD framework materials was identified.

Without the strength and estab-lished design principles of cast metal framework RPDs, it is believed that alternative RPD frameworks have re-duced longevity and significant peri-odontal consequences. Clinical re-ports describe methods to improve their performance.51,52 Studies dem-onstrating poor periodontal or dental response to RPDs have investigated acrylic resin framework RPDs.53-57 The authors found that teeth in contact with acrylic resin frameworks were more likely to have dental disease. Carlson57 confirmed that acrylic resin RPDs had a high incidence of frac-ture or need for repair. In contrast, it is interesting to note that studies with positive long term clinical results used cast metal framework RPDs.40,41,58,59 The authors concluded that there is no direct evidence of well made and maintained RPDs significantly contrib-uting to periodontal disease. In a rare direct comparison of RPD material and design, Bissada et al60 found that inflammation was greater when acrylic resin contacted the gingival tissue than when metal was used. These projects seem to confirm a preference for metal framework RPDs in terms of clinical performance and periodontal health.

While metal frameworks may be preferred, modern RPD framework fit continues to be less than ideal.61-65 There is evidence that the average cli-nician understands and is taught less about the RPD framework fabrica-tion process than in previous genera-tions.66-69 Surveys of dental laboratories and dentists continue to find poor com-munication between the two.27,28,49,70-78 In addition, the majority of RPD pro-

cedures are selected based on their ef-ficiency and economy rather than on the standard of care.75-78 Poor communica-tion and standardization has not been found within the prosthodontic com-munity.79

These quality issues help explain the high frequency of failed treatment in the non-institutionalized U.S. pop-ulation.6,80-82 Further analysis of the type of prostheses requested, design instructions given, and quality of ma-terial provided to the laboratory, may clarify some of the sources of defec-tive RPDs. Considering the previously mentioned factors, an analysis of the incidence of various classes of RPDs would be of interest. It also provides an opportunity to investigate some of the existing trends in non-institution-alized RPD services. The purpose of this study was to investigate patterns of tooth loss in patients receiving RPDs and to present details regarding how this treatment is provided.

MATERIAL AND METHODS

Five regional commercial dental laboratories located in eastern Wis-consin, were chosen for data collec-tion. Laboratories were selected if they were willing to participate, were region-ally located, and they fabricated large numbers of RPDs. RPD was defined as any prosthesis that replaced teeth in a partially dentate arch, and could be re-moved from the mouth and replaced at will.83

The proposed study was approved by all laboratories and the Institu-tional Review Board of Marquette University School of Dentistry, Mil-waukee, Wis. Data were collected by the laboratories using handheld point and shoot digital cameras. Any pre-scription presenting to the laboratory requesting fabrication of a RPD was included. Therefore, repairs and re-lines were excluded.

Two photographs were made of laboratory box contents with pre-scriptions meeting the previously mentioned criteria. The first was made immediately upon receipt at the labo-

The Journal of Prosthetic Dentistry

49July 2011

Pun et alPun et al

Clinical ImplicationsThe inclusive nature of this analysis helps demonstrate details of current RPD treatment that are rarely discussed in dental education or litera-ture. The lack of dentist input, use of nonmetal frameworks, bulky major connectors, and lack of adequately supported RPD designs indicates the potential for poor RPD outcomes in this sample.

Statement of problem. Current demographic information on the number and types of removable partial dentures is lacking in the prosthodontic literature.

Purpose. This study was designed to investigate patterns of tooth loss in patients receiving removable partial dentures (RPDs) in eastern Wisconsin.

Material and methods. Digital images (1502) of casts at 5 dental laboratories in eastern Wisconsin were collected. Any prescription requesting fabrication of a removable partial denture was photographed twice. The first photograph was made immediately upon arrival at the laboratory, while the second photograph was made immediately before being returned to the prescribing dentist for the first time. A calibrated investigator analyzed all the photographs for Kennedy Classification, type of RPD, major connector, and other details. Data were analyzed with descriptive statis-tics. Fisher’s exact test was used to confirm repeatability.

Results. Kennedy Class I was the most common RPD with a frequency of 38.4%. More than 40% of prescriptions had no design input from the dentist. One in 3 RPDs used acrylic resin or flexible frameworks. One in 5 RPDs had no rests. The horseshoe major connector was the most common maxillary major connector, while the lingual plate was the most common in the mandible.

Conclusions. RPDs remain a common prosthodontic treatment in this region. Non-metal RPD frameworks are a com-mon treatment type and rarely include rests. These data indicate a changing partially edentulous patient population and a variable commitment to standard levels of prosthodontic care. (J Prosthet Dent 2011;106:48-56)

Survey of partial removable dental prosthesis (partial RDP) types in a distinct patient population

Deo K. Pun, DMD, MS,a Michael P. Waliszewski, DDS, MsD,b Kenneth J. Waliszewski, DDS, MS,c and David Berzins, PhDd

Marquette University, Milwaukee, Wis

aPrivate practice, Sterling, Ill.bAdjunct Assistant Professor, School of Dentistry.cAdjunct Professor, School of Dentistry.dAssociate Professor and Graduate Program Director, Dental Biomaterials.

Recent investigations analyzed trends in demand for prosthodon-tics in the United States.1,2 More than 95 years ago Hillyer3 noted that as the edentulous condition decreases, the use of removable partial dentures (RPDs) increases. Despite decreas-ing rates of tooth loss, the need for removable prosthodontic treatment remains high.4-6 One consequence

of the profession’s improved preven-tive measures has been an increase in the number of patients who require prosthodontic treatment with RPDs.7-9 Conservative treatment types such as dental implants are expensive. This may limit their availability to lower socioeconomic groups in whom the highest rates of tooth loss occur.10-12 Conventional removable prosthodon-

tic treatment types, therefore, con-tinue to outnumber implant tooth replacements in general practice.13

Multiple RPD classification sys-tems have been proposed.14-20 The Kennedy Classification system is cur-rently the system described in 2 RPD textbooks,21,22 and was found to be the most commonly used system ac-cording to an older analysis.19 This

system also meets criteria of the prin-ciples, concepts, and practices in prosthodontics (PCPP).23

Several attempts to analyze spe-cific trends in the frequency of various RPDs have been presented.24-39 Most of these studies are of European or middle-eastern populations with few studies from the United States.6,40-43

Curtis et al42 surveyed the inci-dence of various classes of RPDs fab-ricated at a single dental laboratory in California. Interim RPDs were ex-cluded, leaving 327 of the 400 work authorizations for inclusion. Forty percent of these RPDs were Kennedy Class I, while 33% were Class II, 18% Class III, and 9% Class IV. The most common mandibular RPD was Class I (49%), and the most common maxil-lary RPD was Class II (38%). Using 5 commercial dental laboratories from different regions of North America, Öwall and Taylor43 investigated the frequency of different types of RPDs. While information regarding number and distribution of teeth was pre-sented, there was no classification. Ninety-five percent of 1,363 RPDs analyzed had cast metal frameworks. Redford’s group found that 8% of the 7,374 examined subjects were using an RPD.6 The prevalence increased with age to 22% at 55 to 64 years old. This finding did not include acrylic resin framework RPDs. In the United States, no recent analysis of incidence or prevalence of types of RPDs or Kennedy Classification was identified.

The previously mentioned studies evaluated data pertaining only to cast metal framework RPDs. This may not reflect the demographics of the aver-age clinical practice. While valid long-term outcome data is lacking, acrylic resin framework RPDs continue to be used with great frequency.44,45 Acrylic resin framework RPDs are far more common than cast metal framework RPDs in several other countries.46-50 As a group, these surveys demonstrated significant differences in patient treat-ment among institutions, government subsidized clinics, and private prac-tice. Insurance reimbursement, capa-

bilities of dental laboratory support, education, and location and extent of missing teeth all appear to influ-ence whether a cast metal framework or acrylic resin RPD is fabricated.49

In addition, newer types of flexible RPDs have received much attention in dental advertisements over the past decade. However, no peer-reviewed study or incidence data for these dif-ferent RPD framework materials was identified.

Without the strength and estab-lished design principles of cast metal framework RPDs, it is believed that alternative RPD frameworks have re-duced longevity and significant peri-odontal consequences. Clinical re-ports describe methods to improve their performance.51,52 Studies dem-onstrating poor periodontal or dental response to RPDs have investigated acrylic resin framework RPDs.53-57 The authors found that teeth in contact with acrylic resin frameworks were more likely to have dental disease. Carlson57 confirmed that acrylic resin RPDs had a high incidence of frac-ture or need for repair. In contrast, it is interesting to note that studies with positive long term clinical results used cast metal framework RPDs.40,41,58,59 The authors concluded that there is no direct evidence of well made and maintained RPDs significantly contrib-uting to periodontal disease. In a rare direct comparison of RPD material and design, Bissada et al60 found that inflammation was greater when acrylic resin contacted the gingival tissue than when metal was used. These projects seem to confirm a preference for metal framework RPDs in terms of clinical performance and periodontal health.

While metal frameworks may be preferred, modern RPD framework fit continues to be less than ideal.61-65 There is evidence that the average cli-nician understands and is taught less about the RPD framework fabrica-tion process than in previous genera-tions.66-69 Surveys of dental laboratories and dentists continue to find poor com-munication between the two.27,28,49,70-78 In addition, the majority of RPD pro-

cedures are selected based on their ef-ficiency and economy rather than on the standard of care.75-78 Poor communica-tion and standardization has not been found within the prosthodontic com-munity.79

These quality issues help explain the high frequency of failed treatment in the non-institutionalized U.S. pop-ulation.6,80-82 Further analysis of the type of prostheses requested, design instructions given, and quality of ma-terial provided to the laboratory, may clarify some of the sources of defec-tive RPDs. Considering the previously mentioned factors, an analysis of the incidence of various classes of RPDs would be of interest. It also provides an opportunity to investigate some of the existing trends in non-institution-alized RPD services. The purpose of this study was to investigate patterns of tooth loss in patients receiving RPDs and to present details regarding how this treatment is provided.

MATERIAL AND METHODS

Five regional commercial dental laboratories located in eastern Wis-consin, were chosen for data collec-tion. Laboratories were selected if they were willing to participate, were region-ally located, and they fabricated large numbers of RPDs. RPD was defined as any prosthesis that replaced teeth in a partially dentate arch, and could be re-moved from the mouth and replaced at will.83

The proposed study was approved by all laboratories and the Institu-tional Review Board of Marquette University School of Dentistry, Mil-waukee, Wis. Data were collected by the laboratories using handheld point and shoot digital cameras. Any pre-scription presenting to the laboratory requesting fabrication of a RPD was included. Therefore, repairs and re-lines were excluded.

Two photographs were made of laboratory box contents with pre-scriptions meeting the previously mentioned criteria. The first was made immediately upon receipt at the labo-

50 Volume 106 Issue 1

The Journal of Prosthetic Dentistry

51July 2011

Pun et al Pun et al

ratory and the second immediately prior to being returned to the pre-scribing dentist for the first time. Im-ages were standardized by placing all contents of a particular incoming box on a 30.5 cm x 40.5 cm background. If received articulated, the articulator or mounting rings were disassembled to allow imaging of the occlusal surfaces of the casts. Personal identifiers such as the patient and dentist name were blocked out prior to photograph-ing using blank pieces of paper. The edges of the background were aligned perpendicular to and within the edges of the camera view screen. The second photograph was made using the same technique as the first, except that all contents leaving the laboratory were placed on the background. Frame-works being returned for trial evalua-tion were placed upon their definitive casts, and processed RPDs without casts were placed with the polished surface facing up.

Calibration of laboratories was conducted on 2 separate occasions. After demonstration, discussion, and practice photography, the laboratory technician in charge of photography was observed during a photographic session. Once calibrated, a summary of instructions was left as a reference. A minimum of 1 follow-up visit to each laboratory was conducted during the initial 2 weeks of data collection. Data collection was planned to continue for a minimum of 4 weeks with a mini-mum sample size goal of 500.

The Kennedy Classification with appropriate modification space enu-meration was listed according to Applegate’s modifications.18 Dental implants were considered ‘abutments’ based on the Kennedy Classification.84 Anterior teeth were considered ‘miss-ing’ if the prosthesis replaced an an-terior tooth. However, third molars, fixed prosthesis pontics, and closed spaces were not considered missing teeth. If an immediate prosthesis was requested, the total number of miss-ing teeth was recorded based on the modified cast.

Design input was considered to

have 4 areas of information: major connector, rests, guiding planes, and clasps. Three levels of design input were considered. Multiple design in-put communicated at least 2 of the 4 basic areas of design through the written prescription. Credit was giv-en if reference was made to a design cast drawing. Minimal design input communicated 1 of the 4 basic areas of design. No written design input communicated 0 of the 4 basic areas of design. Who designed the frame-works in these instances is unknown. The RPD was considered completed if it was returned after processing with all prescribed prosthetic teeth and components attached.

An RPD was considered to be a metal framework if the major connec-tor was cast. The RPD was considered to be acrylic resin if the major connec-tor was processed in acrylic resin. The flexible type RPD was determined by the laboratory prescription, by visu-alization of non-metal clasp assem-blies, or by the differing appearance of the base material. An extension of the RPD onto either a prepared rest seat or over the occlusal or incisal surface of a tooth or dental implant, was considered to meet the defini-tion for a rest.83 Lingual plates, minor connectors, and claps arms were not considered rests, unless they covered an actual rest seat or they involved an

occlusal or incisal surface. Major con-nectors were classified according to calibrated definitions. Less frequent designs were listed as ‘other’ when identified.

As images were collected, the first and second photographs of each subject were matched and numbered according to the laboratory routing number (Fig. 1). The first 10 image sets from each laboratory were viewed by 3 of the investigators independent-ly to confirm data collection criteria (Fig. 2). Once calibrated, 10 new im-age sets from each laboratory were independently reviewed by the inves-tigators. This group of data collection forms was tested using Fisher’s exact test to confirm reliability and accu-racy. In addition, the lead investigator selected and reviewed an additional 10 subject sets. One week later, these same subject sets were again reviewed and the data collection forms were compared using Fisher’s exact test to confirm repeatability. The lead inves-tigator completed review of the re-maining image sets. Once transferred to data collection forms, information was tabulated using a computerized spreadsheet (Microsoft Excel 2010; Microsoft, Redmond, Wash). The totals where then analyzed using de-scriptive statistics.

1 Sample images of prescription for acrylic resin framework RPD.

RESULTS A total of 1502 images were col-

lected. Images with matched photo-graphs (1146) resulted in a total of 573 complete subject sets. The re-maining 356 images were unmatched. Twenty-six of these images were un-readable or requested a reline or re-pair and were excluded. The other 330 images could be used for determining Kennedy Classification resulting in a total of 903 individual subjects (Table I). The modification spaces for Class II and III subjects are summarized in Tables II and III. Sixty percent of Class I RPDs lacked any modification spac-es, while only 21.7% of Class II RPDs lacked the same. Eighty percent of Class III RPDs had either a single mod-ification space or no space indicating a large majority of unilateral or single bilateral edentulous spaces. Overall, there were 377 RPDs fabricated with-

out any modification spaces.Three hundred and twenty-four

of the unmatched images (n=897) could be used for the design input data (Table IV). Forty-two percent (377/897) of the total prescriptions did not provide any design informa-tion. Of the unmatched images, 319 (n=892) were used to determine the material type (Table V). For every 2 metal frameworks, there was 1 non-metal framework.

Analysis of the 573 matched im-ages demonstrated additional details. Seventy-two percent (414/573) of the RPDs were planned for trial evalua-tion. Ninety-seven percent (408/421) of the metal frameworks requested return for trial evaluation. According to the images, 515 casts and 58 im-pressions were received at the labo-ratory. Nearly 7% (38/573) of RPDs replaced anterior teeth only, 47.3% (271/573) replaced posterior only,

and 46.1% (264/573) replaced both anterior and posterior. Nineteen per-cent (110/573) of RPDs were missing between 1 to 3 teeth, The mean num-ber of teeth replaced was 6.

According to the criteria discussed, 78.7% (451/573) of RPDs were con-sidered to have rests (Table V). Tables VI and VII show the major connector types in the matched sample. Overall, the horseshoe (72.5%) was the most frequently used maxillary major con-nector, while the lingual plate (59.4%) was the most frequent mandibular. When analyzed separately, 95.3% of non-metal maxillary major connec-tors were a horseshoe design. Like-wise, 91.1% of non-metal mandibular major connectors were a lingual plate.

The P-values from Fisher’s exact test for investigator versus decision, replication of investigator 1, and rep-lication of investigator 2 were .55, .62, and 1 respectively. This indicates

2 Data recording form.

1. Dental Laboratory:

2. Laboratory serial number: _____________________ Arch: Maxilla / Mandible

3. Lab received: Cast Impression [Alginate] [Rubber]

4. Prescription:

a. Design: _________ Multiple design input

_________ Minimal design input

_________ No written design input

b. State of return: _________ Completed _________ For trial evaluation

5. Pre-prosthesis information:

a. Classification: _________ Modification spaces: _________

b. Total # of missing teeth: _________

c. Distribution: _____ Anterior only _____ Posterior only _____ Both Ant & Post

6. Prosthesis information: Notation:

a. Type of RPD: Metal framework Yes

Acrylic resin or

Flexible (Valplast) No

b. Total # of prosthetic teeth: _________ TBD

c. Type of major connector:

Max: A-P strap Palatal strap Palatal plate Horseshoe

A-P bar Palatal bar Other (specify): ______________________

Mand: Lingual bar Lingual plate Other (specify): ______________________

RPD Data Recording Form

50 Volume 106 Issue 1

The Journal of Prosthetic Dentistry

51July 2011

Pun et al Pun et al

ratory and the second immediately prior to being returned to the pre-scribing dentist for the first time. Im-ages were standardized by placing all contents of a particular incoming box on a 30.5 cm x 40.5 cm background. If received articulated, the articulator or mounting rings were disassembled to allow imaging of the occlusal surfaces of the casts. Personal identifiers such as the patient and dentist name were blocked out prior to photograph-ing using blank pieces of paper. The edges of the background were aligned perpendicular to and within the edges of the camera view screen. The second photograph was made using the same technique as the first, except that all contents leaving the laboratory were placed on the background. Frame-works being returned for trial evalua-tion were placed upon their definitive casts, and processed RPDs without casts were placed with the polished surface facing up.

Calibration of laboratories was conducted on 2 separate occasions. After demonstration, discussion, and practice photography, the laboratory technician in charge of photography was observed during a photographic session. Once calibrated, a summary of instructions was left as a reference. A minimum of 1 follow-up visit to each laboratory was conducted during the initial 2 weeks of data collection. Data collection was planned to continue for a minimum of 4 weeks with a mini-mum sample size goal of 500.

The Kennedy Classification with appropriate modification space enu-meration was listed according to Applegate’s modifications.18 Dental implants were considered ‘abutments’ based on the Kennedy Classification.84 Anterior teeth were considered ‘miss-ing’ if the prosthesis replaced an an-terior tooth. However, third molars, fixed prosthesis pontics, and closed spaces were not considered missing teeth. If an immediate prosthesis was requested, the total number of miss-ing teeth was recorded based on the modified cast.

Design input was considered to

have 4 areas of information: major connector, rests, guiding planes, and clasps. Three levels of design input were considered. Multiple design in-put communicated at least 2 of the 4 basic areas of design through the written prescription. Credit was giv-en if reference was made to a design cast drawing. Minimal design input communicated 1 of the 4 basic areas of design. No written design input communicated 0 of the 4 basic areas of design. Who designed the frame-works in these instances is unknown. The RPD was considered completed if it was returned after processing with all prescribed prosthetic teeth and components attached.

An RPD was considered to be a metal framework if the major connec-tor was cast. The RPD was considered to be acrylic resin if the major connec-tor was processed in acrylic resin. The flexible type RPD was determined by the laboratory prescription, by visu-alization of non-metal clasp assem-blies, or by the differing appearance of the base material. An extension of the RPD onto either a prepared rest seat or over the occlusal or incisal surface of a tooth or dental implant, was considered to meet the defini-tion for a rest.83 Lingual plates, minor connectors, and claps arms were not considered rests, unless they covered an actual rest seat or they involved an

occlusal or incisal surface. Major con-nectors were classified according to calibrated definitions. Less frequent designs were listed as ‘other’ when identified.

As images were collected, the first and second photographs of each subject were matched and numbered according to the laboratory routing number (Fig. 1). The first 10 image sets from each laboratory were viewed by 3 of the investigators independent-ly to confirm data collection criteria (Fig. 2). Once calibrated, 10 new im-age sets from each laboratory were independently reviewed by the inves-tigators. This group of data collection forms was tested using Fisher’s exact test to confirm reliability and accu-racy. In addition, the lead investigator selected and reviewed an additional 10 subject sets. One week later, these same subject sets were again reviewed and the data collection forms were compared using Fisher’s exact test to confirm repeatability. The lead inves-tigator completed review of the re-maining image sets. Once transferred to data collection forms, information was tabulated using a computerized spreadsheet (Microsoft Excel 2010; Microsoft, Redmond, Wash). The totals where then analyzed using de-scriptive statistics.

1 Sample images of prescription for acrylic resin framework RPD.

RESULTS A total of 1502 images were col-

lected. Images with matched photo-graphs (1146) resulted in a total of 573 complete subject sets. The re-maining 356 images were unmatched. Twenty-six of these images were un-readable or requested a reline or re-pair and were excluded. The other 330 images could be used for determining Kennedy Classification resulting in a total of 903 individual subjects (Table I). The modification spaces for Class II and III subjects are summarized in Tables II and III. Sixty percent of Class I RPDs lacked any modification spac-es, while only 21.7% of Class II RPDs lacked the same. Eighty percent of Class III RPDs had either a single mod-ification space or no space indicating a large majority of unilateral or single bilateral edentulous spaces. Overall, there were 377 RPDs fabricated with-

out any modification spaces.Three hundred and twenty-four

of the unmatched images (n=897) could be used for the design input data (Table IV). Forty-two percent (377/897) of the total prescriptions did not provide any design informa-tion. Of the unmatched images, 319 (n=892) were used to determine the material type (Table V). For every 2 metal frameworks, there was 1 non-metal framework.

Analysis of the 573 matched im-ages demonstrated additional details. Seventy-two percent (414/573) of the RPDs were planned for trial evalua-tion. Ninety-seven percent (408/421) of the metal frameworks requested return for trial evaluation. According to the images, 515 casts and 58 im-pressions were received at the labo-ratory. Nearly 7% (38/573) of RPDs replaced anterior teeth only, 47.3% (271/573) replaced posterior only,

and 46.1% (264/573) replaced both anterior and posterior. Nineteen per-cent (110/573) of RPDs were missing between 1 to 3 teeth, The mean num-ber of teeth replaced was 6.

According to the criteria discussed, 78.7% (451/573) of RPDs were con-sidered to have rests (Table V). Tables VI and VII show the major connector types in the matched sample. Overall, the horseshoe (72.5%) was the most frequently used maxillary major con-nector, while the lingual plate (59.4%) was the most frequent mandibular. When analyzed separately, 95.3% of non-metal maxillary major connec-tors were a horseshoe design. Like-wise, 91.1% of non-metal mandibular major connectors were a lingual plate.

The P-values from Fisher’s exact test for investigator versus decision, replication of investigator 1, and rep-lication of investigator 2 were .55, .62, and 1 respectively. This indicates

2 Data recording form.

1. Dental Laboratory:

2. Laboratory serial number: _____________________ Arch: Maxilla / Mandible

3. Lab received: Cast Impression [Alginate] [Rubber]

4. Prescription:

a. Design: _________ Multiple design input

_________ Minimal design input

_________ No written design input

b. State of return: _________ Completed _________ For trial evaluation

5. Pre-prosthesis information:

a. Classification: _________ Modification spaces: _________

b. Total # of missing teeth: _________

c. Distribution: _____ Anterior only _____ Posterior only _____ Both Ant & Post

6. Prosthesis information: Notation:

a. Type of RPD: Metal framework Yes

Acrylic resin or

Flexible (Valplast) No

b. Total # of prosthetic teeth: _________ TBD

c. Type of major connector:

Max: A-P strap Palatal strap Palatal plate Horseshoe

A-P bar Palatal bar Other (specify): ______________________

Mand: Lingual bar Lingual plate Other (specify): ______________________

RPD Data Recording Form

52 Volume 106 Issue 1

The Journal of Prosthetic Dentistry

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Pun et alPun et al

Table I. Kennedy Classification distribution of RPDs

Table II. Kennedy Classification II distribution with Applegate’s modification

Table III. Kennedy Classification III distribution with Applegate’s modification

Table IV. Prescription information on design input

Maxilla

Mandible

Total

Percentage

107

240

347

38.4%

Class I

103

123

226

25.0%

Class II

212

70

282

31.2%

Class III

35

13

48

5.4%

Class IV

457

446

903

100%

TotalArches

Maxilla

Mandible

Total

Percentage

23

26

49

21.7%

Modification0

41

56

97

42.9%

Modification1

30

36

66

29.2%

Modification2

9

5

14

6.2%

Modification3+

103

123

226

100%

TotalArches

Maxilla

Mandible

Total

Percentage

97

24

121

42.9%

Modification0

74

30

104

36.9%

Modification1

29

16

45

16.0%

Modification2

12

0

12

4.2%

Modification3+

212

70

282

100%

TotalArches

Multiple

Minimal

None

Total

380

140

377

897

Frequency

42.4

15.6

42.0

100

%

152

22

72

246/592

Frequency

61.8

8.9

29.3

41.6%

%

219

24

103

346/592

Frequency

63.3

6.9

29.8

58.4

%DesignInput

MandibleMaxilla

Metal Frame OnlyOverall

no significant difference between in-vestigators or in either repeatability case. Thirty RPDs used attachments, usually extracoronal. One framework was fabricated from gold alloy. Four metal frameworks could not be clas-sified based on the definitions used in this study. Eight unilateral prosthe-ses were also found, 4 of which were made from flexible materials. A single swing-lock RPD was found.

DISCUSSION

Previous research from the United States on this topic has been minimal

and does not use as strict a RPD defi-nition. With 903 RPDs fabricated by 5 laboratories within a 4-month peri-od, for a metropolitan area estimated at 1.7 million people, demonstrates the continued demand for this treat-ment type. While the Kennedy Class I continued to be the most common RPD configuration, the difference between classes was reduced.24,40-42 Class III proved more common than in any previous analysis. Inclusion of acrylic resin RPDs, reduced rates of tooth loss, and changes in therapeu-tic strategies for dental disease are all possible explanations. Table VIII com-

pares the current data overall, and with metal frameworks only, to pre-vious analyses. While the nearly even number of maxillary versus mandibu-lar RPDs could be seen as a positive, the increased incidence of maxillary Class III (46.4%) compared to Cur-tis et al42 (23%) may signal a lack of progress towards controlling dental disease or the patient’s ability to af-ford fixed prostheses. The reduced in-cidence of Class IV RPDs (5.4%) and RPDs replacing anterior teeth only (6.6%) may demonstrate rejection of removable prostheses in favor of fixed prostheses for improved esthetics.

Table V. Frequency of RPDs and use of rest

Table VI. Distribution of major connectors according to Kennedy Classifications in maxilla

Table VII. Distribution of major connectors according to Kennedy Classifications in mandible

Metal

Acrylic

Flexible

Total

596

250

46

892

66.8%

28.0%

5.2%

Total Sample

421

128

24

573

73.3%

22.4%

4.2%

Matched Sample

416

35

0

451 78.7%

Rest - Present

5

93

24

122 21.3%

Rest - AbsentRPDType

AP strap

Palatal strap

Palatal plate

Horseshoe

AP bar

Others

Total

8

3

9

55

0

1

76

Class I

8

13

3

39

1

0

64

Class II

8

11

2

97

1

4

123

Class III

3

0

2

16

0

1

22

Class IV

27

27

16

207

2

6

285

Frequency

9.5

9.5

5.6

72.6

0.7

2.1

100

PercentageMaxilla

Lingual bar

Lingual plate

Others

Total

65

96

0

161

Class I

34

46

1

81

Class II

12

25

3

40

Class III

0

5

1

6

Class IV

111

172

5

288

Frequency

38.6

59.7

1.7

100

PercentageMandible

52 Volume 106 Issue 1

The Journal of Prosthetic Dentistry

53July 2011

Pun et alPun et al

Table I. Kennedy Classification distribution of RPDs

Table II. Kennedy Classification II distribution with Applegate’s modification

Table III. Kennedy Classification III distribution with Applegate’s modification

Table IV. Prescription information on design input

Maxilla

Mandible

Total

Percentage

107

240

347

38.4%

Class I

103

123

226

25.0%

Class II

212

70

282

31.2%

Class III

35

13

48

5.4%

Class IV

457

446

903

100%

TotalArches

Maxilla

Mandible

Total

Percentage

23

26

49

21.7%

Modification0

41

56

97

42.9%

Modification1

30

36

66

29.2%

Modification2

9

5

14

6.2%

Modification3+

103

123

226

100%

TotalArches

Maxilla

Mandible

Total

Percentage

97

24

121

42.9%

Modification0

74

30

104

36.9%

Modification1

29

16

45

16.0%

Modification2

12

0

12

4.2%

Modification3+

212

70

282

100%

TotalArches

Multiple

Minimal

None

Total

380

140

377

897

Frequency

42.4

15.6

42.0

100

%

152

22

72

246/592

Frequency

61.8

8.9

29.3

41.6%

%

219

24

103

346/592

Frequency

63.3

6.9

29.8

58.4

%DesignInput

MandibleMaxilla

Metal Frame OnlyOverall

no significant difference between in-vestigators or in either repeatability case. Thirty RPDs used attachments, usually extracoronal. One framework was fabricated from gold alloy. Four metal frameworks could not be clas-sified based on the definitions used in this study. Eight unilateral prosthe-ses were also found, 4 of which were made from flexible materials. A single swing-lock RPD was found.

DISCUSSION

Previous research from the United States on this topic has been minimal

and does not use as strict a RPD defi-nition. With 903 RPDs fabricated by 5 laboratories within a 4-month peri-od, for a metropolitan area estimated at 1.7 million people, demonstrates the continued demand for this treat-ment type. While the Kennedy Class I continued to be the most common RPD configuration, the difference between classes was reduced.24,40-42 Class III proved more common than in any previous analysis. Inclusion of acrylic resin RPDs, reduced rates of tooth loss, and changes in therapeu-tic strategies for dental disease are all possible explanations. Table VIII com-

pares the current data overall, and with metal frameworks only, to pre-vious analyses. While the nearly even number of maxillary versus mandibu-lar RPDs could be seen as a positive, the increased incidence of maxillary Class III (46.4%) compared to Cur-tis et al42 (23%) may signal a lack of progress towards controlling dental disease or the patient’s ability to af-ford fixed prostheses. The reduced in-cidence of Class IV RPDs (5.4%) and RPDs replacing anterior teeth only (6.6%) may demonstrate rejection of removable prostheses in favor of fixed prostheses for improved esthetics.

Table V. Frequency of RPDs and use of rest

Table VI. Distribution of major connectors according to Kennedy Classifications in maxilla

Table VII. Distribution of major connectors according to Kennedy Classifications in mandible

Metal

Acrylic

Flexible

Total

596

250

46

892

66.8%

28.0%

5.2%

Total Sample

421

128

24

573

73.3%

22.4%

4.2%

Matched Sample

416

35

0

451 78.7%

Rest - Present

5

93

24

122 21.3%

Rest - AbsentRPDType

AP strap

Palatal strap

Palatal plate

Horseshoe

AP bar

Others

Total

8

3

9

55

0

1

76

Class I

8

13

3

39

1

0

64

Class II

8

11

2

97

1

4

123

Class III

3

0

2

16

0

1

22

Class IV

27

27

16

207

2

6

285

Frequency

9.5

9.5

5.6

72.6

0.7

2.1

100

PercentageMaxilla

Lingual bar

Lingual plate

Others

Total

65

96

0

161

Class I

34

46

1

81

Class II

12

25

3

40

Class III

0

5

1

6

Class IV

111

172

5

288

Frequency

38.6

59.7

1.7

100

PercentageMandible

54 Volume 106 Issue 1

The Journal of Prosthetic Dentistry

55July 2011

Pun et al Pun et al

When only metal RPDs were consid-ered, Class I was the most common followed in order by Class II, III, and then IV. This is similar to previous studies.24,42

A method similar to Allen and Lynch75 was used to collect prescrip-tion input. Other methods left room for interpretation of drawings, writ-ing, or the various prescription forms. This method identified if minimal in-formation was given and still demon-strated how little input many dentists have upon the RPD design. It must also be noted that the RPDs from the laboratory servicing the dental school had a bias towards ‘multiple design input.’ If only private practice RPDs were analyzed, the rate of no input in-creased. This confirms previous find-ings of the lack of prescribing dentist input,27,28,49,70-74 as well as varying RPD design philosophies.75-78

This study revealed that 66.8% of all RPDs were fabricated with cast metal frameworks. The remaining 33.2% were fabricated with non-met-al major connectors. The incidence of non-metal RPDs found in the current study is higher than the 5% found by Öwall and Taylor43 using similar in-clusion/exclusion criteria. However, this number is less than that reported by several recent international stud-ies.46,48,49

The standard design feature meant to minimize soft tissue dam-age from RPDs is the rest. Despite a broad definition, only 78.7% of RPDs used any rest. Therefore, 1 in 5 RPDs were completely tissue-borne pros-theses. In addition, many RPDs that received credit for a rest were lacking in adequate support due to design and modification shortcomings. When non-metal RPDs were evaluated, only 23% were considered to have a rest. This may explain the frequent observa-tion of periodontal tissue damage with these prostheses and RPDs in general.

With the amount of advertising promoting flexible RPD frameworks, it was somewhat surprising to find only 5.2% of these within the sample. None of these RPDs were considered to have

a rest. Perhaps this was due to the manufacturer claims of superior stabil-ity and retention of frameworks made from these materials. The authors were unable to locate any peer-reviewed or manufacturer-sponsored research in regards to the clinical performance of these materials.

The majority of maxillary ma-jor connectors in this study (72.5%) were of the horseshoe design. Only 27 (9.5%) palatal straps were found. This is disappointing considering it was shown to be the most comfortable maxillary major connector and gener-ally covered the least amount of gingi-val tissue.85 Öwall and Taylor43 found 56% of maxillary major connectors to be horseshoes, while Curtis et al42 did not find any. This demonstrates the necessity to define clearly each major connector type as well as potential re-gional differences in RPD design. It is believed that the definitions used were clear, easy to use, and based upon the prosthodontic consensus despite room for debate. The definition for a lingual bar was a mandibular major connector located lingual to the den-tal arch with visible gingival tissue lin-gual to any anterior tooth. Essentially, a lingual plate was required to cover the gingiva lingual to all remaining an-terior teeth. Despite this, a majority of lingual plate major connectors was still found (59.4%). This is greater than in other studies.42,43 The large majority of horseshoe and lingual plate major connectors was likely due to non-metal RPD strength requirements. Bulky, wide versions of the horseshoe and lingual plate were selected nearly all of the time when non-metal major connectors were used. However, when only metal frameworks were consid-ered, the majority were horseshoes and lingual plates.

Despite calibration, high labora-tory volumes and study deadline were the likely reasons for missing the sec-ond image. In a few instances, it was noticed that the ‘incoming’ photo-graph was made after completion of the RPD. This was an issue for some criteria since the laboratory may have

done a design drawing or made a cast prior to the initial image. One solu-tion was to have the research investi-gators collect the images themselves. This was not considered logistically possible when using multiple labora-tories for an extended time period. While a single image was adequate for most data, several questions required both images. Considering this, it was understood that the 330 accepted but unmatched images provided reli-able and usable information.

Only RPDs for patients already in treatment were tabulated. There-fore, these numbers do not reflect the prevalence of RPDs or tooth distribu-tion within the general population. However, by including all RPD types a broad picture of the partially eden-tulous population receiving this type of care was analyzed. Overall, the en-countered limitations proved minor considering the large number of RPDs collected and the simplistic nature of the critical data analyzed. The find-ings support the need for continued periodic regionally specific analysis. In addition, clinicians, insurers, and public health professionals in the state of Wisconsin should be mindful of the quality of removable prosth-odontic care being delivered in this region. Considering how frequently acrylic resin and flexible type RPDs are used in the general community, it is disappointing that no clinical studies for these treatments could be found for patients in the United States.

CONCLUSIONS

This study evaluated images of 903 RPDs made at 5 dental labora-tories located in eastern Wisconsin. The Kennedy Classification according to Applegate’s modification, material, and major connector type, as well as other information was identified. The following conclusions were drawn from the study:

1. RPDs of all types continue to be a common treatment type with equal incidence in the maxillary and man-dibular arch.

2. Kennedy Class I RPDs remain the most common (38.4%) with Class III RPDs demonstrating an increased incidence (31.2%) at the expense of the other classifications.

3. Dentist input into RPD designs and fabrication continues to be minimal.

4. The incidence of non-metal frame-works (33.2%) in this region of the U.S. is higher than previously reported.

5. There is a high incidence of RPDs lacking any tooth support (21.3%) in this region.

6. An increased incidence of the bulkiest major connectors was seen in this sample when compared to previ-ous data.

REFERENCES

1. Douglas CW, Watson AJ. Future needs for fixed and removable partial dentures in the United States. J Prosthet Dent 2002;87:9-14.

2. Marcus SE, Drury TF, Brown LJ, Zion GR. Tooth retention and tooth loss in the per-manent dentition of adults: United States, 1988-1991. J Dent Res 1996;75:684-95.

3. Hillyer E. The retention of partial dentures. Den Cosmos 1915;57:1019-22.

4. Ettinger RL, Beck JD, Jakobsen J. Removable prosthodontic treatment needs: a survey. J Prosthet Dent 1984;51:419-27.

5. Hunt RJ, Strisilapanan P, Beck JD. Denture-related problems and prosthodontic treatment needs in the elderly. Gerodontics 1985;1:226-30.

6. Redford M, Drury TF, Kingman A, Brown LJ. Denture use and the technical quality of dental prostheses among persons 18-74 years of age: United States, 1988-1991. J Dent Res 1996;75:714-25.

7. Harvey WL, Hoffman W Jr. Ten-year study of trends in removable prosthodontic ser-vice. J Prosthet Dent 1989;62:644-6.

8. Joshi A, Douglas CW, Feldman H, Mitchell P, Jette A. Consequences of success: do more teeth translate into more disease and utilization? J Public Health Dent 1996;56:190-7.

9. Manski RJ, Moeller JF, Maas WR. Dental services. an analysis of utilization over 20 years. J Am Dent Assoc 2001;132:655-64.

10.Burt BA, Ismail AI, Morrison EC, Beltran ED. Risk factors for tooth loss over a 28-year period. J Dent Res 1990;69:1126-30.

11.Eklund SA, Burt BA. Risk factors for total tooth loss in the United States; longitudinal analysis of national data. J Public Health Dent 1994;54:5-14.

12.Dolan TA, Gilbert GH, Duncan RP, Foerster U. Risk indicators of edentulism, partial tooth loss, and prosthetic status among black and white middle-aged older adults. Community Dent Oral Epidemiol 2001;29:329-40.

13.Janus CE, Hunt RJ, Unger JW. Survey of prosthodontic service provided by gen-eral dentists in Virginia. J Prosthet Dent 2007;97:287-91.

14.Bailyn CM. Tissue support in partial denture construction. Den Cosmos 1928;70:988-97.

15.Kennedy E. Partial denture construction. Brooklyn: Dental Items of Interest Publish-ing Company; 1928. p. 3-8.

16.Cummer W. An outline of the theory and practice of partial denture service. J Amer Dent Assoc 1922;9:735-54.

17.Skinner C. A Classification of removable partial dentures based upon the principles of anatomy and physiology. J Prosthet Dent 1959;9:240-6.

18.Applegate OC. The rationale of partial den-ture choice. J Prosthet Dent 1960;10:891-907.

19.Miller EL. Systems for Classifying par-tially dentulous arches. J Prosthet Dent 1970;24:25-40.

20.McGarry TJ, Nimmo A, Skiba JF, Ahlstrom RH, Smith CR, Koumjian JH, et al. Clas-sification system for partial edentulism. J Prosthodont 2002;11:181-93.

21.McGivney GP, Carr AB. McCracken’s removable partial prosthodontics 10th ed. St. Louis: Elsevier; 2000. p.19-23.

22.Phoenix RD, Cagna DR, DeFreest CF. Stew-art’s clinical removable partial prosthodon-tics. 4th ed. Hanover Park: Quintessence; 2008. p. 8-17.

23.Academy of Prosthodontics. Principles, concepts, and practices in prosthodontics. J Prosthet Dent 1995;73:73-94.

24.Anderson JN, Sheff BD, Lammie GA. A clinical survey of partial dentures. Br Dent J 1952;92:59-67.

25.Anderson JN, Bates JF. The cobalt-chro-mium partial denture: A clinical survey. Br Dent J 1959;107:57-62.

26.Tomlin HR, Osborne J. Cobalt-chromium partial dentures: A clinical survey. Br Dent J 1961;110:307-10.

27.Basker RM, Davenport JC. A survey of partial denture design in general dental practice. J Oral Rehabil 1978;5:215-22.

28.Basker RM, Harrison A, Davenport JC, Marshall JL. Partial denture design in gen-eral dentalPractice--10 years on. Br Dent J 1988:165:245-9.

29.Derry A, Bertram U. A clinical survey of removable partial dentures after 2 years us-age. Acta Odontol Scand 1970;28:581-98.

30.Axéll T, Owall B. Prevalences of remov-able dentures and edentulousness in an adult Swedish population. Swed Dent J 1979;3:129-37.

31.Björn A, Owall B. Partial edentulism and its prosthetic treatment: A frequency study within a Swedish population. Swed Dent J 1979;3: 15-25.

32.Laine P, Murtomaa H. Frequency and suppliers of removable dentures in Finland in 1983. Community Dent Oral Epidemiol 1985;13:47-50.

33.Tervonen T, Bergenholtz A, Nordling H, Ainamo A, Ainamo J. Edentulousness and the use of removable dentures among people 25, 35, 50 and 65 years old in Ostrobothnia, Finland. Proc Finn Dent Soc 1985;81:264-70.

34.Bergman B, Hugoson A, Olsson CO. Periodontal and prosthetic conditions in patients treated with removable partial dentures and artificial crowns. A longitu-dinal two-year study. Acta Odont Scand 1971;29:621-38.

35.Yeung AL, Lo EC, Clark RK, Chow TW. Usage and status of cobalt-chromium removable partial dentures 5-6 years after placement. J Oral Rehabil 2002;29:127-32.

36.Wetherell JD, Smales RJ. Partial denture failures: A long term clinical survey. J Dent 1980;8:333-40.

37.Keyf F. Frequency of the various Classes of removable partial dentures and selection of major connector and direct/indirect retain-ers. Turk J Med Sci 2001;31:445-9.

38.Jepson NJ, Thomason JM, Steele JG. The influence of denture design on patient acceptance of partial dentures. Brit Dent J 1995;178:296-300.

39.Al-Dwairi ZN. Partial edentulism and re-movable denture construction: a frequency study in Jordanians. Eur J Prosthodont Restor Dent 2006;14:13-7.

40.Schwalm CA, Smith DE, Erickson JD. A clinical study of patients 1 to 2 years after placement of removable partial dentures. J Prosthet Dent 1977;38:380-91.

41.Chandler JA, Brudvik JS. Clinical evalua-tion of patients eight to nine years after placement of removable partial dentures. J Prosthet Dent 1984;51:736-43.

42.Curtis DA, Curtis TA, Wagnild GW, Finzen FC. Incidence of various Classes of remov-able partial dentures. J Prosthet Dent 1992;67:664-7.

43.Öwall BE, Taylor RL. A survey of dentitions and removable partial dentures construct-ed for patients in North America. J Prosthet Dent 1989;61:465-70.

44. Walmsley AD. Acrylic partial dentures. Dent update 2003;30:424-9.

45.Allen PF, Jepson NJ, Doughty J, Bond S. Attitudes and practice in the provision of removable partial dentures. Br Dent J 2008;204:E2.

46.Lewandowska A, Speichowicz E, Owall B. Removable partial denture treatment in Poland. Quintessence Int 1989;20:353-8.

47.Thean HP, Payne JA, Jeganathan S. The use of removable partial dentures amongst private dental practitioners in Singapore. Singapore Dent J 1996;21:26-30.

48.Radhi A, Lynch CD, Hannigan A. Quality of written communication and master impres-sions for fabrication of removable partial prostheses in the Kingdom of Bahrain. J Oral Rehabil 2007;34:153-7.

49.Schwarz WD, Barsby MJ. A survey of the practice of partial denture prosthetics in the United Kingdom. J Dent 1980;8:95-101.

50.Lynch CD, Allen PF. The teaching of remov-able partial dentures in Ireland and the United Kingdom. Br Dent J 2007;203:E17.

51.McCartney JW, Fiks S. The all-acrylic resin mandibular removable partial denture: design considerations. J Prosthet Dent 1997;77:638.

52.Smith RA, Rymarz FP. Cast clasp transi-tional removable partial dentures. J Pros-thet Dent 1969;22:381-5.

54 Volume 106 Issue 1

The Journal of Prosthetic Dentistry

55July 2011

Pun et al Pun et al

When only metal RPDs were consid-ered, Class I was the most common followed in order by Class II, III, and then IV. This is similar to previous studies.24,42

A method similar to Allen and Lynch75 was used to collect prescrip-tion input. Other methods left room for interpretation of drawings, writ-ing, or the various prescription forms. This method identified if minimal in-formation was given and still demon-strated how little input many dentists have upon the RPD design. It must also be noted that the RPDs from the laboratory servicing the dental school had a bias towards ‘multiple design input.’ If only private practice RPDs were analyzed, the rate of no input in-creased. This confirms previous find-ings of the lack of prescribing dentist input,27,28,49,70-74 as well as varying RPD design philosophies.75-78

This study revealed that 66.8% of all RPDs were fabricated with cast metal frameworks. The remaining 33.2% were fabricated with non-met-al major connectors. The incidence of non-metal RPDs found in the current study is higher than the 5% found by Öwall and Taylor43 using similar in-clusion/exclusion criteria. However, this number is less than that reported by several recent international stud-ies.46,48,49

The standard design feature meant to minimize soft tissue dam-age from RPDs is the rest. Despite a broad definition, only 78.7% of RPDs used any rest. Therefore, 1 in 5 RPDs were completely tissue-borne pros-theses. In addition, many RPDs that received credit for a rest were lacking in adequate support due to design and modification shortcomings. When non-metal RPDs were evaluated, only 23% were considered to have a rest. This may explain the frequent observa-tion of periodontal tissue damage with these prostheses and RPDs in general.

With the amount of advertising promoting flexible RPD frameworks, it was somewhat surprising to find only 5.2% of these within the sample. None of these RPDs were considered to have

a rest. Perhaps this was due to the manufacturer claims of superior stabil-ity and retention of frameworks made from these materials. The authors were unable to locate any peer-reviewed or manufacturer-sponsored research in regards to the clinical performance of these materials.

The majority of maxillary ma-jor connectors in this study (72.5%) were of the horseshoe design. Only 27 (9.5%) palatal straps were found. This is disappointing considering it was shown to be the most comfortable maxillary major connector and gener-ally covered the least amount of gingi-val tissue.85 Öwall and Taylor43 found 56% of maxillary major connectors to be horseshoes, while Curtis et al42 did not find any. This demonstrates the necessity to define clearly each major connector type as well as potential re-gional differences in RPD design. It is believed that the definitions used were clear, easy to use, and based upon the prosthodontic consensus despite room for debate. The definition for a lingual bar was a mandibular major connector located lingual to the den-tal arch with visible gingival tissue lin-gual to any anterior tooth. Essentially, a lingual plate was required to cover the gingiva lingual to all remaining an-terior teeth. Despite this, a majority of lingual plate major connectors was still found (59.4%). This is greater than in other studies.42,43 The large majority of horseshoe and lingual plate major connectors was likely due to non-metal RPD strength requirements. Bulky, wide versions of the horseshoe and lingual plate were selected nearly all of the time when non-metal major connectors were used. However, when only metal frameworks were consid-ered, the majority were horseshoes and lingual plates.

Despite calibration, high labora-tory volumes and study deadline were the likely reasons for missing the sec-ond image. In a few instances, it was noticed that the ‘incoming’ photo-graph was made after completion of the RPD. This was an issue for some criteria since the laboratory may have

done a design drawing or made a cast prior to the initial image. One solu-tion was to have the research investi-gators collect the images themselves. This was not considered logistically possible when using multiple labora-tories for an extended time period. While a single image was adequate for most data, several questions required both images. Considering this, it was understood that the 330 accepted but unmatched images provided reli-able and usable information.

Only RPDs for patients already in treatment were tabulated. There-fore, these numbers do not reflect the prevalence of RPDs or tooth distribu-tion within the general population. However, by including all RPD types a broad picture of the partially eden-tulous population receiving this type of care was analyzed. Overall, the en-countered limitations proved minor considering the large number of RPDs collected and the simplistic nature of the critical data analyzed. The find-ings support the need for continued periodic regionally specific analysis. In addition, clinicians, insurers, and public health professionals in the state of Wisconsin should be mindful of the quality of removable prosth-odontic care being delivered in this region. Considering how frequently acrylic resin and flexible type RPDs are used in the general community, it is disappointing that no clinical studies for these treatments could be found for patients in the United States.

CONCLUSIONS

This study evaluated images of 903 RPDs made at 5 dental labora-tories located in eastern Wisconsin. The Kennedy Classification according to Applegate’s modification, material, and major connector type, as well as other information was identified. The following conclusions were drawn from the study:

1. RPDs of all types continue to be a common treatment type with equal incidence in the maxillary and man-dibular arch.

2. Kennedy Class I RPDs remain the most common (38.4%) with Class III RPDs demonstrating an increased incidence (31.2%) at the expense of the other classifications.

3. Dentist input into RPD designs and fabrication continues to be minimal.

4. The incidence of non-metal frame-works (33.2%) in this region of the U.S. is higher than previously reported.

5. There is a high incidence of RPDs lacking any tooth support (21.3%) in this region.

6. An increased incidence of the bulkiest major connectors was seen in this sample when compared to previ-ous data.

REFERENCES

1. Douglas CW, Watson AJ. Future needs for fixed and removable partial dentures in the United States. J Prosthet Dent 2002;87:9-14.

2. Marcus SE, Drury TF, Brown LJ, Zion GR. Tooth retention and tooth loss in the per-manent dentition of adults: United States, 1988-1991. J Dent Res 1996;75:684-95.

3. Hillyer E. The retention of partial dentures. Den Cosmos 1915;57:1019-22.

4. Ettinger RL, Beck JD, Jakobsen J. Removable prosthodontic treatment needs: a survey. J Prosthet Dent 1984;51:419-27.

5. Hunt RJ, Strisilapanan P, Beck JD. Denture-related problems and prosthodontic treatment needs in the elderly. Gerodontics 1985;1:226-30.

6. Redford M, Drury TF, Kingman A, Brown LJ. Denture use and the technical quality of dental prostheses among persons 18-74 years of age: United States, 1988-1991. J Dent Res 1996;75:714-25.

7. Harvey WL, Hoffman W Jr. Ten-year study of trends in removable prosthodontic ser-vice. J Prosthet Dent 1989;62:644-6.

8. Joshi A, Douglas CW, Feldman H, Mitchell P, Jette A. Consequences of success: do more teeth translate into more disease and utilization? J Public Health Dent 1996;56:190-7.

9. Manski RJ, Moeller JF, Maas WR. Dental services. an analysis of utilization over 20 years. J Am Dent Assoc 2001;132:655-64.

10.Burt BA, Ismail AI, Morrison EC, Beltran ED. Risk factors for tooth loss over a 28-year period. J Dent Res 1990;69:1126-30.

11.Eklund SA, Burt BA. Risk factors for total tooth loss in the United States; longitudinal analysis of national data. J Public Health Dent 1994;54:5-14.

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Corresponding author:Dr Michael P. Waliszewski13780 W. Greenfield Ave #780Brookfield, WI 53005Fax: 262-782-7720Email: michael.waliszewski@mu.edu

AcknowledgmentsThe authors thank all participating labora-tories, as well as Cole Stockheimer, a 4th year dental student, for assistance with data collection.

Copyright © 2011 by the Editorial Council for The Journal of Prosthetic Dentistry.

A technique for fabricating a 2-part surgical template

Mohammad Aljadi, DDS,a Geoffrey A. Thompson, DDS, MS,b Masaaki Izumi, RDT,c and Gerald J. Ziebert, DDS, MSd

Marquette University School of Dentistry, Milwaukee, Wis

aResident, Department of Graduate Prosthodontics.bAssistant Director, Department of Graduate Prosthodontics. cLab Technician, Department of Graduate Prosthodontics. dDirector, Department of Graduate Prosthodontics. (J Prosthet Dent 2011;106:57-60)

1 Duplicated cast of tooth preparations with margins outlined.

Implant placement should be re-storatively driven to eliminate or reduce complications during the restorative phase.1 The correct placement and an-gulation of dental implants are nec-essary for the functional and esthetic success of the prosthesis. Often, the restorative dentist will complete a di-agnostic waxing to determine implant placement. This information, along with radiographs and the clinical ex-amination, aids the restorative dentist in determining implant angulation, ce-mentoenamel junction (CEJ) position, and the mesiodistal and buccolingual position of the implant. This informa-tion is transferred to the surgeon via a surgical template, eliminating guess-work at the time of surgery.4

Many types of surgical templates are available, ranging from the acrylic resin template with a titanium sleeve to the computer-assisted designed and manufactured guided implant surgical template.2-3 The advantages of guided templates include accurately guiding implant placement, the possibility of flapless surgery, and reduced surgical time. However, not every patient can afford a computerized tomogram and a computer-designed surgical guide. Thus, the primary disadvantage of this guide is cost. Conversely, the acrylic resin and titanium sleeve surgical guide is comparatively inexpensive and easy to fabricate. However, it does not permit the surgeon to use successive

surgical drills as only the pilot drill will fit into the titanium sleeve. Some sur-geons will use this type of template for the pilot drill only, completing the rest of the osteotomy free-hand. This ap-proach could result in less than ideal implant placement with concomitant restorative problems. The esthetic out-come may also be affected.

This article presents an inexpen-sive and relatively easy technique for fabricating a surgical template that transfers necessary information, in-cluding the CEJ position, implant an-gulation, and the mesiodistal position of the implant to the surgeon. Also, this template can be used throughout the drilling sequence. When fabricat-ing this device, the restorative dentist should consider anatomical struc-tures and morphology that may in-fluence choice of implant location. In the patient situation depicted, some

of the natural teeth were used to re-tain a complete arch provisional res-toration and to allow for sequencing implant placement.

TECHNIQUE

1. Make an irreversible hydrocol-loid impression (Impr Essix; Dent-sply Glenroe, Bradenton, Fla) of the mouth preparations for the purpose of fabricating a diagnostic waxing. Ensure that the preparation margins are exposed in the same manner as if a provisional restoration was being made indirectly (Fig. 1).

2) After completing the diagnos-tic waxing, make stone casts (Mi-crostone; Whip mix Corp, Louisville, Ky) duplicating the preparations and waxing. Make a heavy-bodied putty silicone matrix (Aquasil Easy Mix Put-ty; Dentsply Caulk, Milford, Del) of