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Tanta Dental Journal 11 (2014) 139e149www.elsevier.com/locate/tdj

Effect of implant assisted partial overdenture with neutral zoneconcept in partially resected mandible restoration on facial contour

and bone density

Shaimaa A. Mohamed a,*, H.M. Amin a, A.A. Sadakah b, N.A. Kashef a

a Prosthodontics Dept., Faculty of Dentistry, Tanta University, Egyptb Oral & Maxillofacial Surgery Dept., Faculty of Dentistry, Tanta University, Egypt

Received 1 April 2014; revised 7 July 2014; accepted 14 July 2014

Available online 29 September 2014

Abstract

This study was performed to evaluate the effect of implant assisted partial overdenture located in neutral zone for restoringpartially resected mandible on facial contour and bone density.Material and methods: 10 patients their age range from 18 to 45 years were selected. Each patient had partially resected mandiblewith osseous bone graft. Patients received removable partial overdenture assisted by two implants with suitable length and diameterguided by CBCT scan using early loading protocol two months after implant insertion. That partial overdenture respected neutralzone registration. Patients were recalled after two months from transitional partial denture insertion, two months after implantinsertion and two months after implant assisting removable partial overdenture for facial symmetry evaluation, and assessment ofbone quality. The data were collected, tabulated and statistically analyzed using test (ANOVA) with repeated measures comparingdifferent follow up periods for bone density, and paired t-test comparing facial symmetry before reconstruction versus afterreconstruction and mirror images to healthy side.Results: Currently it was found that early loading protocol with two implants supported mandibular partial overdenture withneutral zone in reconstructed resected mandible produce implant success rates, and improve facial asymmetry.© 2014, Production and Hosting by Elsevier B.V. on behalf of the Faculty of Dentistry, Tanta University.

Keywords: Removable partial overdenture; Implant; Neutral zone; Resected mandible; Facial symmetry; Cone beam scan

Open access under CC BY-NC-ND license.

* Corresponding author.

E-mail addresses: dr.shimaaahmed@yahoo.com (S.A. Mohamed), hodaamin@hotmail.com, hoda.rashad@dent.tanta.edu.eg (H.M. Amin),

sadakah@hotmail.com, abdelfatah.abdelfatah@dent.tanta.edu.eg (A.A. Sadakah), nahed.kashef@dent.tanta.edu.eg (N.A. Kashef).

Peer review under the responsibility of the Faculty of Dentistry, Tanta University

Production and hosting by Elsevier

http://dx.doi.org/10.1016/j.tdj.2014.07.003

1687-8574/© 2014, Production and Hosting by Elsevier B.V. on behalf of the Faculty of Dentistry, Tanta University.Open access under CC BY-NC-ND license.

1 Planmecax ray machine, Japan.

140 Sh.A. Mohamed et al. / Tanta Dental Journal 11 (2014) 139e149

1. Introduction

Mandibular discontinuity most commonly occurs asa result of tumor resection. It may also occur as sequelof infection or trauma. Loss of mandibular continuityresults in varying degrees of internal and facial changewhich cause impairment in appearance, mastication,speech, deglutition, self-image, and significant restor-ative problems. These occur through the loss of sup-porting structures, the presence of scar tissue, andirregular tissue topography. It may also produce non-repeatable mandibular movements and alteredmaxillo-mandibular relationships [1].

Several prosthetic options make the prognosis forthese patients greatly improved. Rehabilitation withcomplete or partial dentures even when mandibularreconstruction is ideal may be difficult due to lack ofstability or retention. The use of osseointegrated im-plants as a solution in these cases of mandibular de-fects has been accepted [2].

Implant supported overdenture achieves best hy-gienic maintenance, easy soft tissue follow up and lowrealizing cost [3]. The placement of dental implantsrequires meticulous planning and careful surgicalprocedures. A combination of a limited bone volume,poor bone quality and anatomical variations may leadto less predictable bone apposition and early implantfailure. A thorough radiographic imaging assists in thetherapy, preoperative treatment planning, surgicalprocedure, and in the postoperative assessment anongoing implant function [4]. Cone Beam CT (CBCT)is an imaging technology that generates a 3D volumeof image data which facilitate the accurate selectionand location of implant [5].

Regarding the increase stabilization potential ofrehabilitation for these patients neutral zone determi-nation takes place. This physiologically based denturedesign concept has been shown to be effective formandibular removable prostheses particularly patientsaffected by anatomic deformity or insufficiencythrough facilitating the development of vertical denturepolished surfaces against which effective facial sealcan be achieved and maintained [6].

Regarding the increase potential of facial appear-ance, data from various studies of facial symmetry havebeen collected using a variety of different materials andmethods which change with the speeding progress ofscience from the beginning of old techniques ofmeasuring such as spreading and sliding calipers,cephalometric radiographs and technique of anthro-pometry to a large variety of non-contact methods tomeasure three dimensional facial geometry such as laser

scanning, stereo-photogrammetry, infrared imaging orcomputed tomography. However, most of these methodshave inherent limitations [7].

Many methods have been proposed for mandibularreconstruction, most researchers evaluated the tech-niques. However few studies have focused on evalua-tion of facial contour for this reconstruction [8]. Thestudy of implant assisted removable partial overdenturelocated in neutral zone for partial mandibulectomy andtheir effect in facial contour restoration was consideredas wide area of research [9]. Thus it was the aim of thisstudy to evaluate the effect of implant assisted partialoverdenture located in neutral zone for restoringpartially resected mandible on facial contour and bonedensity.

2. Materials and methods

10 patients of 18e45 years have been selected fromthose admitted to Prosthodontic Department, Facultyof Dentistry, Tanta University. They all signed a writ-ten consent revised by the research ethical committeeof Tanta University, to approve their agreement ofbeing a part of the current research. All patients had apartially resected mandible with osseous bone graft(Fig. 1A). They were not subjected to chemotherapy orradiotherapy for at least one year before prosthetictreatment. Patients had their manual dexterity neces-sary to place and remove implant assisted prosthesisand to provide adequate oral hygiene around the im-plants. The prosthetic management of patients wasdone as: not.

2.1. Pre-operative analysis

Patients were subjected to radiographic examinationby using Cone Beam CT scan1 of the mandible. Pa-tient's photographs were taken in frontal views of eachpatient's face in the natural head position with a digitalcamera as a record for patients to be evaluated beforeprosthetic construction. Every partially resectedmandible patient received conventional partial denturewith neutral zone registration which then acted as presurgical stent [6,9,15].

2.2. Implant insertion

In the partially resected side, all patients receivedtwo root form osseointegrated endosseous screw vent

Fig. 1. A. Intra-oral view of patients with hemi mandibulectomy with osseous bone graft. B. Show fixture assuming its final position. C. The

applying the cover screw. D. The ball insert abutments were screwed in place. E. Shows impression with an elastomeric impression material after

abutment insertion. F. The metallic removable framework. G. Shows external impression to define denture polished surface contours within the

neutral zone. H. Extra oral view showing partial denture after teeth arrangement in neutral zone. I. Shows intra-oral view of final implant assisted

partial overdenture with neutral zone.

141Sh.A. Mohamed et al. / Tanta Dental Journal 11 (2014) 139e149

type implants2 with suitable length and diameter whichwere determined by cone beam scan using PlanmecaRomix® software. Implant received removable partialoverdenture using early loading protocol as twomonths after implant insertion [10]. This was done as:

At time of surgery, the oral mucosa and paraoralskin were painted and rubbed with antiseptic tincture torender the surgical field free from microorganisms.Gaining access to the operation field was made througha horizontal incision passing along the buccal side ofthe reconstructed mandible. The flap was reflected inboth buccal and lingual directions using a periostealelevator to expose the entire buccolingual width of thebone graft. The pilot drill was used to penetrate thebone graft to establish the proper location and angu-lations of the two implants fixtures. The bone graftsites were gradually widened and adjusted to fit thefixtures by means of specially designed drills of suc-cessively increasing dimensions.

2 Zimmer company, Germany.

The premounted fixtures were then placed in theprepared sites (Fig. 1B), first by finger, then by theratchet wrench in a clock-wise direction. When thefixture has assumed its final position, the mount wasloosened and removed with the hex driver. Fixtureinstallation was then completed by applying the coverscrew with the hex driver (Fig. 1C), to prevent bonefrom growing over the heads of the fixtures duringhealing, and by readapting the flap carefully by meansof interrupted polyamide mattress sutures. A stress freehealing period of two months was suggested to ensurea predictable physical union of the bone graft andimplant fixtures [11].

After healing period (two months) has been elapsed,the submerged implants were exposed as follows: Thesoft tissue covering the bone graft at the marked areaswas locally anaesthetized and the cover screws wereexposed through an incision flap. The cover screw wereunscrewed and removed using the healing cap hex-driver in an anti-clock wise direction. The ball insertabutments were screwed in place with a ball insertabutment seating tool [11], (Fig. 1D).

Fig. 2. Show facial parameter.

142 Sh.A. Mohamed et al. / Tanta Dental Journal 11 (2014) 139e149

2.3. Prosthetic rehabilitation procedures

The prosthetic procedures started about one weekafter the abutment connection where every patientreceived an implants retained metallic partial over-denture with a neutral zone technique. Primaryimpression of the mandibular residual ridge was madewith Alginate impression material.3 Soon, the pre-liminary impressions were poured in dental stone,4 andthe study casts were prepared. On the mandibular studycast, four main items were carried out: primarysurveying, primary drawing of the design for a metallicRPD, construction of a custom tray with adequatespacer especially over the teeth and implant super-structures, charting of possible mouth preparation [12].

The suggested mouth preparations were then carriedout in the patient mouth to receive the metal frame-work. The custom trays were fabricated with self-cureresin keeping the borders 2 mm short of the sulcus andgreen compound border molding was done. Theassembled O ring housing was reseated on the implantabutment and an impression was made with an elas-tomeric impression material,5 then the assembly wasremoved again and kept aside. The secondaryimpression was poured in dental stone and a mastercast was prepared and a record block was made. On themandibular master cast, three main items were carriedout; surveying to confirm the adequacy of mouthpreparations, final drawing of the design for a metallicRPD, usual modifications of the master cast with agreat attention paid to the relief at the implant site toprovide enough space between the subsequent acrylicbase and the implant superstructure.

The metallic removable framework was then fabri-cated using the standard technique for construction of aconventional metallic framework [12], (Fig. 1F). Themetallic framework was tried in the patient's mouth toensure adequate seating of the framework. The implantassisted partial overdenture with neutral zone tech-nique was done as follows [6]. The permanent base wasprepared in heat cure resin.6 Hot red modeling plasticimpression compound7 was applied to the record baseto facilitate adhesion of the rim. In a water bath set to60 �C, the edges of the recording rim were sealed tothe record base using a heated spatula. Two sticks ofgreen modeling plastic impression compound were

3 Kromopan, Lascod SPA-Laboratori Scientific Odontoiatria, Italy.4 Moldano stone plaster W. German.5 Ventura Products Dental, B.S.ASeArgentina.6 Superacryl/Resin for dentures. Sofa.7 Impression Compound; Kerr Corp.

placed; the material was kneaded thoroughly, and wasadapted to the record base, forming a recording rim.The edge of the recording rim was sealed to the recordbase using a heated spatula.

The completed record base and recording rim wasplaced in the water bath for approximately 2 min inpreparation for the clinical procedure. The base andrim was removed from the water bath and quicklyplaced intraorally. The patient was instructed to swal-low. Next, a cup of warm water was provided to thepatient and patient was instructed to sip and swallow.The patient repeated this sip and swallow exerciseseveral times until the volume of the neutral zone re-cord was detected. When the neutral zone record hascooled and hardened, excess modeling plastic impres-sion compound displaced superior to the intendedocclusal plane during the recording procedure waseliminated.

Then to develop the lingual neutral zone index, theneutral zone record was seated on the mandibulardefinitive cast. Laboratory putty8 was prepared to aworkable consistency and was adapted into the tonguespace of the neutral zone record. The template waspositioned over the tongue space, and the putty was

8 Poly V Putty; Accurate Set, Inc., Newark, NJ.

Fig. 3. A. CBCT scan shows bone density of osseous bone graft at baseline, B. bone density 2 months after implant insertion, C. bone density 2

months after implant loading. The measurement of bone quality around implant, area, width.

143Sh.A. Mohamed et al. / Tanta Dental Journal 11 (2014) 139e149

formed to the template to facilitate its placement dur-ing denture tooth arrangement, the facial index wasdeveloped as the same manner. Once polymerized,both the lingual and facial indices were removed andensured that they can be replaced accurately andsecurely on the cast in the absence of the neutral zonerecord. The mandibular teeth were arranged within theneutral zone (Fig. 1H), as dictated by the facial andlingual indices [6].

In preparation for external impressions used todefine denture polished surface contours within theneutral zone, carefully all base plate wax apical todenture teeth on the facial and lingual aspects of themandibular trial denture and the facial and palatalaspects of the maxillary trial denture were removed.Required orofacial movements with the patient werepracticed prior to making impressions. Low-viscosityimpression material9 was applied on to facial aspectsof the mandibular trial denture, and the trial denturewas placed into the patient's mouth (Fig. 1G). Thepatient was instructed to pucker the lips forward,smile broadly, move the mandible into protrusive

9 Elite P&P Normal Set; Dentsply Caulk.

posture, and then move the mandible from side toside. The patient repeated these movements severaltimes. The trial denture was removed and theimpression was evaluated. Excess impression materialwas trimmed and all material covering the dentureteeth was eliminated. Finally, an external impressionalong the mandibular lingual flanges was made as theprevious technique. The trial denture was removedand denture flange dimensions and extension wasexamined [6].

After the acrylic resin had polymerized, the denturewas removed and examined for the orientation of theattachment in the denture to verify that the attachmentwas properly placed and secured [12], (Fig. 1I). Thepatient was instructed about the care of the denture andthe oral hygiene procedures. The patient was thenscheduled for both clinical and radiographic follow ups.

3. Results

Patients were called for any necessary adjustmentand all the patients instructed to follow ups after twomonths of implant insertion and two months afterimplant assisting removable partial overdenture inser-tion for:

tedifference

betweenbefore

prostheticandafterprosthetic.Diff.2:absolute

difference

betweenmirrorandafter.P:Pvalueforpairedt-testforcomparingbetweendifferent1and

Statistically

significantat

P�

0.05.

gle

AAngle

Bexre

exl

meexr

meexl

chre

chl

mechI

meChr

BEReBMC

BELeBMC

ff. 1

Diff.2

Diff.1

Diff.2

Diff.1

Diff.2

Diff.1

Diff.2

Diff.1

Diff.2

Diff.1

Diff.2

Diff.1

Diff.2

Diff.1

Diff.2

Diff.1

Diff.2

Diff.1

Diff.2

0.7

4.8

10.8

0.5

0.45

0.15

0.31

0.09

0.31

0.11

0.39

0.09

0.09

0.01

0.24

0.06

0.47

0.13

0.7

16.7

0.5

0.18

0.12

0.39

0.03

0.67

0.03

0.43

0.05

0.54

0.01

0.11

0.01

0.52

00.36

0.01

0.7

1.6

00.43

0.03

0.16

0.02

0.6

0.04

0.38

0.21

0.14

0.12

0.12

0.04

0.37

00.23

0.02

2.2

11.3

0.51

0.1

0.2

0.02

0.25

0.06

0.37

0.03

0.1

00.1

0.01

0.32

0.1

0.33

0.08

3.6

1.1

3.8

0.68

0.39

0.18

0.23

0.49

0.05

0.43

0.08

0.28

0.05

0.09

0.03

0.31

0.04

0.29

0.04

0.5

0.3

1.5

1.06

0.17

0.39

0.2

0.75

0.06

0.25

0.11

0.04

0.08

0.23

00.14

0.16

0.28

0.06

0.1

3.5

0.2

1.09

0.03

0.28

0.01

0.89

0.01

0.41

0.02

0.1

0.1

0.31

0.02

0.12

0.02

0.02

0.02

3.1

10.1

7.7

0.32

0.13

0.19

0.06

0.22

00.2

0.1

0.05

0.04

0.29

0.09

0.37

0.98

0.04

0.95

2.4

7.5

1.3

1.53

0.16

0.68

0.14

0.8

00.67

0.16

0.41

0.04

0.28

0.05

1.23

0.13

1.22

0.21

0.2

4.8

0.4

0.18

0.09

0.1

0.09

0.08

0.01

0.17

0.17

0.01

0.05

0.22

0.04

0.5

0.13

0.4

0.14

70

0.073

0.006*

0.004*

0.001*

0.001*

0.043*

<0.001*

0.099

0.215

144 Sh.A. Mohamed et al. / Tanta Dental Journal 11 (2014) 139e149

3.1. Facial symmetry evaluation and follow up

The facial symmetry evaluated by photo editingsoftware for facial symmetry by using mirror imagingtechnique by creating a binary image for the actualfacial image of patients then using Photoshop v7.0software10 for measuring. The following 10 parameters(2 angle and 8 measurements of width), (Fig. 2) weremeasured with scale bar [9].

1. Distance between the bilateral exocanthions (BE;exreexl)

2. Distance between the median line and the rightexocanthion (meexr)

3. Distance between the median line and lift exo-canthion (meexl)

4. Distance between the bilateral mouth corners(BMC; chrechl)

5. Distance between the median line and right chei-lion (meChr)

6. Distance between the median line and left cheilion(mechI)

7. Distance between the bilateral exocanthions rightand bilateral mouth right (BEreBMC)

8. Distance between the bilateral exocanthions leftand bilateral mouth right (BEleBMC)

9. Angle (A)� of the affected side between the hori-zontal line through the bilateral exocanthions (BE)and line through the bilateral mouth corners(BMCr)

10. Angle (Ayj)� of the healthy site between thehorizontal line through the bilateral exocanthions(BE) and line through the bilateral mouth corners(BMCl)

3.2. Radiographic evaluation

Cone beam CT scan was used for assessment ofbone quality and osseointegration for early loadedimplant [13,14] (Fig. 3).

3.3. Statistical analysis

Statistical analysis were performed using a statisti-cal software package SPSS.11 The data with conven-tional removable partial denture insertion and after itsuse and insertion of removable partial overdenturewere collected, tabulated and statistically analyzed

Table

1

Diff.1:absolu

different2.*:

Patients

An

Di

14.5

21.1

35.5

40.5

55

62.4

70.5

81.2

99

10

2.1

P0.0

10 Adobe systems, Mountain View, CA.11 SPSS release 16.0, SPSS Chicago І 11.

145Sh.A. Mohamed et al. / Tanta Dental Journal 11 (2014) 139e149

using Paired t-test for comparison of facial symmetrybetween before reconstruction, after reconstruction andmirror images to healthy side and test (ANOVA) withrepeated measures for comparing between differentfollow up for bone density.

The results of this study shaded a highlight on theability of the implant assisted overdenture with neutralzone to improve facial asymmetry and ability to regainit to the main facial symmetry image by using thesemeasurements of ten facial parameters. Photographs offaces investigate asymmetry before implant assistedprosthetic rehabilitation and investigate significantimprovement in facial symmetry after implant assistedprosthetic rehabilitation, and the success of the implantassisted overdenture with neutral zone to correct thedifference in regard to the main facial symmetryimage. It was shown that there was significant corre-lation between the width of all parameters to explainthis success results (P < 0.05) except the angle be-tween BE and BMC. However there was no correlationbetween the angle between the BE and BMC and thewidth of the various parameters (P > 0.05). (Table 1),(Figs. 5 and 6).

This current study shaded also more light on bonedensity around the two implants in reconstructed bonein the resected side at the baseline and throughoutstudy follow-up two months after implant placementand two months after implant loading with prosthesis.The result of this study showed significant improve-ment in bone density around two implants from thebaseline, two months after implant insertion and twomonths after implant assisted partial overdenture withneutral zone concept. No significant difference be-tween anterior and posterior implant in bone densityduring follow up period (Fig. 4).

A B

0

200

400

600

800

1000

1200

Pre 2m after implant 2m after implant over denture

Bon

e den

isty

for a

nter

ior

impl

ant

Mea

n

Fig. 4. A. Bar graphs show comparison between bone density at the baselin

loading in the implants. B. Comparison between bone density around anterio

two months of early loading.

4. Discussion

In this study implant assisted overdenture withneutral zone technique was used for rehabilitation ofthe partially constructed resected mandible due toimplant-assisted overdentures requiring an appropriatecameo surface to prevent harmful forces from actingon the implant [15].

The neutral zone concept is useful for predicting thecorrect implant position. Techniques described here areintended to emphasize and illustrate the clinical valueof recording the physiologic dynamics of oral andperioral muscle function and of using this informationto develop denture contours and denture tooth posi-tions. Arranging artificial teeth within the neutral zoneachieves 2 important objectives: (1) prosthetic teeth donot interfere with normal muscle function; and (2)normal oral and perioral muscle activity imparts forceagainst the dentures that serves to stabilize and retainthe prostheses rather than cause denture displacementachieved by conventional denture used for those pa-tients [15].

The objectives of the preoperative implant conebeam scan were currently included all necessary sur-gical and prosthetic information to determine thequantity, quality and angulations of bone; selection ofthe potential implant sites, and size (length and width)by Planmeca Romix software [14]. Early loadingprotocol was proposed in this study due to reduceoverall treatment time, discomfort, increase high pa-tient acceptance and better function [16]. In this study,a new method (measurement of horizontal angularfacial asymmetry of the faces) [9] was used of hemimandibulectomy patient by collating photographs offrontal view for a face by digital camera this required

0

200

400

600

800

1000

1200

1400

2m after implant 2m after implant over denture

Anterior

Posterior

e, after two month of implant insertion and after two month of early

r and posterior implant after two months of implant insertion and after

Fig. 5. Graph shows significant change in facial symmetry before and after reconstruction, with no significant difference between mirror image

and after reconstruction indicating success in regaining facial symmetry.

146 Sh.A. Mohamed et al. / Tanta Dental Journal 11 (2014) 139e149

orientation of the patient to be seated comfortably withFrankfort horizontal plane (external auditory meatus toorbital) parallel to the floor and with the head in areproducible posture and at 1.5 m distance from thecamera lens. The outer canthi of the eyes were used toform a baseline from which a midline could be con-structed. A line was drawn connecting the outercanthus of eye. These particular points were chosen toform the baseline, because they are easily visualized ona frontal photograph and are relatively immobile. Thebaseline formed by connecting the canthi served as themajor baseline for the construction of other baseline tomeasure the amount of deviation [9].

The result of this study showed significant changein angle of the affected side and angle of the healthysite before and after implant assisted overdenture.Also the significant change in distance between thebilateral exocanthions (BE; exreexl), distance be-tween the median line and the right exocanthion (m-exr), distance between the median line and left exo-canthion (m-exl), distance between the bilateralmouth corners (BMC; chrechl), distance between themedian line and right cheilion (m-Chr), and distancebetween the median line and left cheilion (m-chI)before and after implant assisted overdenture, and thenon-significant difference between this parameters

Fig. 6. A, B, C Show: patient's face with asymmetry before any prosthetic reconstruction. a, b, c show patient's face symmetry after implant

assisted partial overdenture with neutral zone insertion.

147Sh.A. Mohamed et al. / Tanta Dental Journal 11 (2014) 139e149

after implant assisted overdenture and mirror imagesfor patients. That mean there was correlation betweenthe angle between the BE and BMC and the width ofthe various parameters (P < 0.05), (Figs. 2 and 6).This study explained the findings that the orbitsexhibited the degree, incidence of asymmetry andfacial asymmetry which was in agreement with Rossiet al. [17], Haraguchi et al. [18] but that disagreedwith Song et al. [9], who concluded that the orbits

exhibited the lowest degree and incidence of asym-metry among individual structures of the face,whereas the mouth was the most asymmetrical, fol-lowed by the ear due to facial asymmetry is moreexaggerated on the lower third of the face because oflateral deviation of the jaw.

The using of implant assisted overdenture withneutral zone correct the facial symmetry by regainingthe soft tissue support to the reconstructed resected

148 Sh.A. Mohamed et al. / Tanta Dental Journal 11 (2014) 139e149

mandible and enhance oral function, withoutconsuming time (early loading). That was accepted byPekkan et al. [15] who concluded that the positiveeffects of the implant supported prosthesis with neutralzone technique are not only to accomplish thementioned statements for the denture and the patient,but also to act as a critical determinant of facial profile.

Studies [13,19,20] have shown that density (quality)of available bone for implant placement is consideredas factor influence the success of implant. Eckert et al.[19] and Young-Dai Song et al. [20] concluded thatbone quality evaluated by CBCT has correlations withprimary implant stability. This suggests that bonequality is one of the factors that require evaluationbefore implant surgery. In the literature [14,21,22], itwas found that CBCT measurements considered ac-curate than CT measurements. However cone beam CTwas used in this study to evaluate bone density aroundimplant site throughout follow up period.

The significant improvement of bone densityreferred to implant success, parallel to Lekholm, Zarb,and others, [23e25] who concluded that sufficientbone density and volume are therefore crucial factorsfor ensuring implant success. Our study explained thisresult due to pre surgical evaluation of bone density byCBCT which indicate the type of bone in the selectedsite. The significant improvement of bone density afterearly loading of implant results in implant successwhich was explained by placement of implant in theneutral zone which prevents harmful forces from actingon implants.

5. Conclusion

This study concluded that: early loading protocolwithtwo implants supported mandibular overdenture inreconstructed resected mandible produce implant suc-cess rates. CBCT scan is the best modality for preoper-ative planning, intra operative and postoperativeassessment including all necessary surgical and pros-thetic information to determine the quantity, quality(density) and angulations of bone; selection of the po-tential implant sites, and size (length and width).Recording of neutral zone as a part of the diagnosticworkup before implant placement is important for improvingthe function and esthetic and regaining facial symmetry.Mandibular reconstruction using implant assisted over-dentures with neutral zone correct facial asymmetry at ahigher degree than before reconstruction.

The usage of implant assisted overdenture withneutral zone corrects the facial symmetry, enhances oralfunction, and improves the quality of life for many

patients without time consuming of time. Regainingfacial symmetry with the mandibular reconstructiveprocedure used is difficult to restore symmetry to thesame level as can be found in the binary images but itdecrease the difference between them. Althoughosseointegrated implants enable the solution of mostobstacles in mandibulectomy cases, they are not usuallyproviding the total answer to the removal of the com-promises inherent in every case. The extent of the sur-gical resection, the location, quality of the remainingstructures and patient's desire for additional surgerymaydictate the need to alter the basic principles usuallyapplied.

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