Attachment Retained Removable Partial Denture: A Case Report Sumit Makkar,1

Anuj Chhabra,2 Amit Khare3

Introduction

Our ever-increasing knowledge of the oral environment, together with technological

improvements and good armamentarium, has taken us to give a restoration which is

esthetically pleasing and comfortable. This makes it all the more important to

reconcile what is actually feasible with the patient's own expectations.

Rehabilitation of partially edentulous situations can be challenging when it is distal

extension situations where a fixed prostheses cannot be fabricated. Implant retained

restoration are an option but this is sometimes not possible due to insufficient amount

of bone or economic reasons. In these cases acrylic or cast partial denture was largely

preferred, with barely satisfactory esthetical results.

Precision attachment has long been considered the highest form of partial denture

therapy. Attachment retained RPD is the treatment modality that can facilitate both

esthetic and a functional replacement of missing teeth and oral structures. The few

retrospective studies available show a survival rate of 83.3% for 5 years, of 67.3% up to

15 years and of 50% when extrapolated to 20 years. [1,2]

This article outlines some of the essential considerations in planning of a precision

attachment retained partial denture with a clinical report.

An attachment is a connector consisting of two or more parts. One part is

connected to a root, tooth, or implant and the other part to prosthesis.

Precision attachments can be classified in to four main groups[3]

.

1. Intracoronal attachments: are mainly used in connecting units of fixed partial

prostheses, retaining restorations with distal extension or bounded removable

prostheses.

2. Extracoronal attachments. This type of attachment provides stability and

retention for removable distal extension prostheses.

3. Stud attachments. Usually in the form of ball & socket, this attachment serves

primarily for overdenture stabilization and retention of the prosthesis. Swiss

logic, ZAAG, Zest anchor is example of stud attachments. One of the

advantages of stud is that they promote better oral hygiene and crown root

ratio is improved with low profile stud attachments.

4. Bar attachments. Originally used for splinting groups of teeth, currently used

IJCDS • MAY, 2011 • 2(2) © 2011 Int. Journal of Clinical Dental Science

ABOUT THE AUTHORS

1) Dr. Sumit Makkar MDS.

Senior Lecturer,

Department of

Prosthodontics, ITS-Centre

for Dental Research &

Studies, Muradnagar

Ghaziabad.

2) Dr. Anuj Chhabra MDS.

Reader,

Department of

Prosthodontics, ITS-Centre

for Dental Research &

Studies, Greater Noida.

3) Dr. Amit Khare MDS.

Reader, Department of

Prosthodontics, Peoples

college of Dental Sciences

and research centre,

Bhopal.

Corresponding Author:

Dr. Sumit Makkar

Department of Prosthodontics

ITS-Centre for Dental

Research & studies,

Muradnagar Ghaziabad.

E- mail:

sumitmakkad@gmail.com

Contact no: 91-9268138938.

Abstract Attachment-retained Removable Partial Denture (RPD) is not an outdated treatment modality.

It is even more contemporary in today's appearance-oriented society than when it was first

introduced. There is significant number of patients who could benefit from this treatment

option, both short and long term. However, lack of proper knowledge, overwhelming number

of attachments available in the market, multiple adjustments and repairs are making dentist

reluctant to offer and provide attachment-retained RPD to their patients. The purpose of this

article is to provide an overview and a simplified approach to this treatment modality by a

clinical case report.

KEYWORDS: Attachment , Removable Partial Denture

CASE REPORT

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IJCDS • MAY, 2011 • 2(2) © 2011 Int. Journal of Clinical Dental Science

logic, ZAAG, Zest anchor is example of stud attachments.

One of the advantages of stud is that they promote

better oral hygiene and crown root ratio is improved

with low profile stud attachments.

4. Bar attachments. Originally used for splinting

groups of teeth, currently used for overdenture retention

and stabilization.

Indications and contraindications for precision

retained partial denture

The variability in the circumstances for use of

attachments and the variety of attachments available

preclude the establishment of a standard model.

Selection of precision attachment should be based on

the functional and physiologic requirements of the

prosthesis. Consideration of the laboratory expertise

in using particular attachments must be

contemplated.

The overwhelming indication for the attachment RPD is

aesthetics. Numerous skilfully designed conventional

RPDs are not worn simply because the patient does not

like the appearance. Elimination of the buccal or labial

direct retainer or clasp arm is a key factor in establishing

an esthetically acceptable design.

The contraindications to the use of attachments in RPDs

are numerous. Short clinical crowns prove to be the

foremost contraindication to the use of attachments in

the construction of RPDs. The tooth must have adequate

crown height to house the attachment components and

effectively offset the leverage forces exerted on the

crown. In addition, adequate height must be present for

the corresponding attachment components to be

housed within the RPD framework or supportive acrylic

resin while allowing an optimal artificial tooth placement [1,2,3

.4,5,6]

Biomechanics and support for attachment retained

RPD

Once a decision has been made to restore a region

with attachment prosthesis, the manner in which the

vertical and horizontal forces are to be supported

requires consideration. A partial prosthesis may be

tooth borne or tooth-tissue borne. Attachments for

Kennedy Class III and Class IV tooth-supported

prostheses should be considered solid, whereas large

Class IV and distal extension I or II prostheses which

are increasingly tissue supported and it should be

considered resilient. Rigid attachment allows virtually

no movement between the prosthesis and the

abutment tooth. Resilient attachments allow for a

spectrum of movement ranging from limited

uniplanar to universal. Staubli[6]

has categorized rigid

and resilient attachments into six classifications, from

rigid to universal resiliency. The higher classification

number correlates with a greater degree of resiliency

and suggests less torque transfer to the root or

implant abutment.

Table :1 Classification of attachments

Class 1a Solid, rigid, non-resilient

Class 1b Solid , rigid, lockable with U- pin.

Class 2 Vertical Resilient

Class 3 Hinge Resilient

Class 4 Vertical and Hinge Resilient

Class 5 Rotational and vertical resilient

Class 6 Universal , Omniplanar

In general, the more precise or rigid the attachment

design is, the greater is the degree of indirect retention

inherent in the design. Additionally, the more widely

spaced the retainers are, the greater the support and

stability are when compared with a design with retainers

placed closely together.

With the aid of a surveyor, the anticipated path of

insertion must be evaluated to develop appropriate

guiding planes and attachment placement within the

confines of the natural dentition. A less resilient

attachment will generally dictate a smaller degree of

tolerance or more parallelism relative to the path of

insertion.

Selection of attachment

Proper attachment selection requires evaluation of 3

factors: location, retention and available space.

Location: Intracoronal attachments are incorporated

entirely within the contours of the cast crown for the

tooth. The advantage of the intracoronal attachment is

that the forces exerted by the prosthesis are applied

more closely to the long axis of the tooth. Intracoronal

attachments are nonresilient and may require double

abutting or splinting of the adjacent teeth. This form of

attachment offers indirect retention and a more precise

path of placement.

The three-dimensional size of the tooth will predict the

functional or biomechanical success with this

attachment. A clinical crown of greater than 4 mm is

generally required with a similar faciolingual width.[7]

In

situations with diminished attachment length as a result

of reduced interocclusal height, milled lingual bracing

arms should be considered.

Extracoronal attachments are situated external to the

developed contours of the crown. The majority of

extracoronal attachments have resilient attributes.

Attachment alignment is not as critical in highly resilient

extracoronal attachments due to the omniplanar motion

possible. This creates the advantage of multiple paths of

placement for the prosthesis. Patients with

biomechanical limitations not withstanding a rigid

attachment apparatus or anatomic limitations precluding

a finite path of placement are strong candidates for

resilient attachments.

Table :1 Classification of attachments

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IJCDS • MAY, 2011 • 2(2) © 2011 Int. Journal of Clinical Dental Science

Retention: Retention of the attachment components may

be based on frictional, mechanical, frictional-mechanical,

magnetic, and suction characteristics. Frictional retention

is developed by the resistance to the relative motion of

two or more surfaces in contact. Greater surface contact

will usually correlate with an increase in the amount of

retention. Mechanical retention implies the resistance to

relative motion by means of a physical undercut. The

degree of undercut and the ability to adjust the physical

component will predict retention. Magnetic retention is

created by attraction of certain materials to a

surrounding field of force produced by the motion of

electrons and atomic alignment.[8]

They were not effective

until a small but strong closed field cobalt-samarium (co-su)

magnet was developed that would fit on to the surface of a

tooth. A metal keeper is attached to the tooth surface,

usually into the root canal and the magnet is contained

within the resin of the denture base. The alloy in the magnet

produces a magnetic force that is both constant and

extraordinary strong. Suction is created by a negative

pressure similar to the intaglio surface of a denture to

the supportive residual ridge.

Space: Space is a principal consideration for the selection

of an attachment. Vertical space is measured from free

gingival margin to the marginal ridge of the abutment.

Cautious placement of the superior aspect of the

attachment will circumvent occlusal interferences. The

length of attachments that rely on frictional retention

should be maximized to maintain resistance to

dislodgment. Placement of the attachment should be as

low on the tooth as possible to reduce the tipping or

leverage forces applied. Buccolingual space is equally

important to avoid over contouring the crown.

Additional bulk will be required buccal and lingual to the

attachment for the casting alloy. Proper analysis of

mesiodistal measurement ensures proper proximal

contour and will provide an indication of a need for

boxes in the development of the preparation. The largest

attachment possible should be selected. This requires

careful preparation analysis that includes the

arrangement of denture teeth in a diagnostic wax-up.

This will help ensure the highest functional and esthetic

value to the reconstruction.

Case report

A 55-year old female reported to private dental practice

with chief complain of missing teeth in lower posterior

region and inability to eat food. She was wearing a distal

extension removable partial denture and the presence of

mandibular extra coronal clasp retainers was negatively

affecting the aesthetics. On clinical examination

mandibular 2nd

premolar, 1st

& 2nd molar were absent

and mandibular canine & 1st premolar was of adequate

height with sound periodontal support.

In lieu of compromised aesthetics, impaired function with

existing partial denture it was planned to construct

mandibular removable partial denture with extracoronal

attachment. The patient rejected the options of implants

because of the need for additional surgery and the

unacceptable duration of treatment phase.

TECHNIQUE[9]

1. Diagnostic impressions were made and mounted on

semi adjustable articulator using a face bow.

Following which diagnostic wax-up was done on the

mounted casts.

2. A putty matrix (Express STD Putty; 3M ESPE, St. Paul,

Minn.) was made over the completed diagnostic wax-up

for evaluation of the existing space for the extracoronal

resilient attachment.

3. The attachment system was selected on the basis of

available space. (OT CAP, Rhein 83 Inc, USA)

4. Tooth preparation was done on mandibular canine

and 1st premolar to receive PFM crowns ( Fig :1).

Impression was made and poured in die stone. Following

which crowns have been waxed to full contour and

milled in wax for maximum guiding plane surface. The

patrices was added to the axial surfaces of the abutment

using a dental surveyor, lingual to the centre of proximal

contour. This ensures that the bulk of matrice does not

interfere with esthetic of buccal cusp of replacing

denture tooth. (Fig :2)

5. Following which casting, finishing, and veneering of

the fixed component was done.(Fig: 3)

6. The fixed component including veneered metal-

ceramic crowns & the patrices were tried in the patient

mouth ( Fig: 4) and a pick-up impression was made

(Imprint II; 3M ESPE).

7. The matrices of the attachments was placed in the

receptacles ( patrice of the attachments) which were in

the crowns on the refractory cast .

8. The wax up of framework of the removable partial

denture was done, invested and casted.

9. The framework was evaluated in the patient mouth

and jaw relation was done using occlusal rims.

10. Try-in was done and acrylisation of removable partial

denture was performed.

Fig : 1 Tooth Preparation done on 43,44

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IJCDS • MAY, 2011 • 2(2) © 2011 Int. Journal of Clinical Dental Science

Discussion

Dr. Herman Chayes[10]

first reported the invention of

attachment in early 20th

century. To the late 20th

century,

with growing technology the attachment has been

applied to the superstructure of implant. Precision

attachment has exceptional feature of being a removable

prosthesis with improved aesthetics, less post-operative

adjustments and better patient comfort.[7]

They are

mostly indicated in long edentulous spans, distal

extension bases and non parallel abutments.

Understanding the difference in nature and behaviour of

the tissues supporting RPD is critical for long term

success of the prosthesis10

. These differences multiplied

by the function create major stresses on the tooth-tissue

prosthesis. The stress-control on abutment is an essential

factor for the success of distal extension cast partial

denture which is achieved through dual impression

technique, broad coverage and stable denture base, rigid

design, physiologic shimming, splinting of abutments,

proper selection of attachment and clasp design.[11-12]

In this case report abutments were of adequate clinical

crown height to receive attachment; multiple abutments

were splinted anterior to edentulous span to aid in

better distribution of stresses. Kapur et al[13]

has

suggested that splinted 1st and 2

nd premolar by full

coverage crown , has provided good support and

improved the prognosis of cast partial denture.

Moreover Extra coronal OT CAP[14]

are castable

attachments with elastic retention. With its elasticity it is

possible to control the flexure and construct a resilient

and shock absorbing prostheses.

Summary & Conclusion

Removable partial dentures fabricated with precision

attachments are the viable options for patients in whom

fixed prosthesis, implants are contraindicated. Adherence

to precision techniques, proper diagnosis and periodic

recall preventative therapy will result in successful

treatment and preservation of the patient's existing

dentition.

References

1. Burns DR, Ward JE. A review of attachments for

removable partial denture design: part 1.

Classification and selection. Int J Prosthodont.

1990;3:98-102.

2. Burns DR, Ward JE. A review of attachments for

removable partial denture design: part 2.

Treatment planning and attachment selection.

Int J Prosthodont 1990;3:169-74.

3. Preiskel HW. Precision attachment in

prosthdontics.1&2. London: Quintessence

Publishing Co Ltd,1995

Fig: 2 Wax Pattern with Patrice attached.

Fig: 3 PFM Crowns with Patrice attached

Fig: 4 PFM Crowns trial in the mouth

Fig: 5 Final Prosthesis in Occlusion.

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IJCDS • MAY, 2011 • 2(2) © 2011 Int. Journal of Clinical Dental Science

4. Baker JL, Goodkind RJ. Precision attachment

removable partial dentures. San Mateo, CA:

Mosby, 1981.

5. Schuyler CH. An analysis of the use and relative

value of the precision attachment and the clasp

in partial denture planning. J Prosthet Dent 1953;

3:711-4.

6. Staubli PE. Attachments & implants: reference

manual. 6th edn. San Mateo, CA: Attachments

International, 1996.

7. Feinberg E. Diagnosing and prescribing

therapeutic attachment-retained partial

dentures. NYS Dent J.1982;48(1):27-29.

8. Gillings BRD. Magnetic retention for complete

and partial dentures Part 1. J Prosthet Dent

1981;45:484.

9. Lorencki FS. Planning Precision attachment

restorations. J Prosthet Dent 1969;21(5):506-508.

10. Preiskel HW. Precision Attachments in

Prosthodontics: Overdentures and Telescopic

Prostheses. Volume 2. Chicago, II: Quintessence

Publishing Co,Ltd; 1985.

11. Preiskel H. Precision attachments for free-end

saddle prostheses. Br Dent J 1969;127:462-468.

12. Picton DC, Willis DJ. Viscoelastic properties of

the periodontal memebrane and mcous

membrane. J Prosthet Dent 1978;40:263-72.

13. Kapur KK, Deupree R, Dent RJ, Hasse AL. A

randomized clinical trail of two basic removable

partial denture designs. Part-I: Comparsion of

five year success rates and periodontal health. J

Prosthet Dent 1994;72(3):268-82.

14. Attachment and Prefabricated Castables

Component. Accessed on 2011 april 11.

Available from: http://www.rhein83.com.

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