Cairo Dental Journal (24) Number (I), 1:10 January, Ahmad Fahmy 1, Ehab M. Abuelroos 2 and Mohammad M. Nada 3

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1 Cairo Dental Journal (24) Number (I), 1:10 January, 2008 Effect of Using Attachment on Implant Supported Distal Extension Lower Partial Over-dentures Ahmad Fahmy 1, Ehab M. Abuelroos 2 and Mohammad M. Nada 3 1. Assistant Lecturer, Prosthodntic Department, Faculty of Oral and Dental Medicine, Cairo University 2. Lecturer, Prosthodntic Department, Faculty of Oral and Dental Medicine, Cairo University. 3. Professor, Prosthodntic Department, Faculty of Oral and Dental Medicine, Cairo University. Abstract This study was performed to evaluate the effect of using attachment on implant supported distal extension lower partial overdenture. Ten lower kennedy class II partially edentulous patients were selected to receive implant at second molar area, then patients were divided into 2 groups according to the implant superstructures either (dome shaped-or-ball and cap attachment). Patients of both groups receive removable partial denture of the same design. Patients were followed up for one year both clinically and radiogarphically. The results showed no statically difference between the treatment plans. It could be concluded that Tooth-implant supported partial denture with or without attachment may be reasonable and simple solution for Kennedy class II partial denture. Ball and socket attachment could be considered as more favorable solution than the dome shaped one regarding prosthetics function and patients satisfaction. INTRODUCTION The unilateral distal extension base removable partial denture has always been associated with a number of problems, specifically concerning support, retention and stability. Most of these problems could be attributed to the absence of the posterior abutment (Wilson et al., 1987). Since, the difference in displacement between the mucosa and the periodontal ligament of last standing abutment was estimated to be up to 25 times (Wills and Manderson, 1977; Picton and Wills, 1978; Monteith, 1984). Consequently, when functional pressure is applied to the distal extension base removable partial denture, the resultant forces are extremely damaging to the abutment teeth and must be controlled if clinical treatment is to be successful (Phoenix et al., 2003). Aydinlik et al., 1983, pointed out that those patients with distal extension ridges may be treated by, a removable partial denture, a cantilever type of fixed partial denture, an implant denture. The authors clarified that the most conventional treatment is by a removable partial denture however, due to the lack of a distal abutment tooth, the denture may move to an undesirable extent during function. Rasmussen, 1987 clarified that osseointegrated implant-borne removable prostheses has been tried with reasonable success in partially edentulous cases with severely resorped ridges and patients with periodontally compromised remaining teeth. The incorporation of implants may enhance its longevity as they provide

2 (2) Ahmed Fahmy, et al. C.D.J. Vol. 24. No. (I) adjunct to the existing dentition by distributing forces and loads to the implant and reducing the stresses placed on the remaining teeth through the prostheses. In the same way, Keltjens et al., (1993) found that placement of osseointegrated implants beneath distal extension denture base of the cast framework could result in stable and durable occlusion and improved functional comfort. Starr, (2001) Clarified that using a posterior implant in cases of free end saddle cases to provide retention through using ball attachment; this treatment option offers greater function, esthetics, comfort and minimal maintenance up to 7 years. Moreover, Masahiro et al., (2003) suggested that the use of the ball / 0-ring attachment could be advantageous for implant supported overdentures with regard to optimizing stress and minimizing partial denture movement. Gerlad et al. (2006) mentioned that both ball attachments and resilient telescopic crowns used on isolated implants in the edentulous mandible are viable treatment options. Implant success and peri-implant condition did not differ between ball attachments and telescopic crowns used as retention modalities for implant overdentures, but the frequency of technical complications was significantly higher with ball attachments than with resilient telescopic crowns. Materials and methods Twenty partially edentulous patients indicated for implant installation were selected from Out patient clinic, Faculty of Oral and Dental Medicine, Cairo University. All patients had Kennedy class II lower partially edentulous ridges with canine or first premolar being the last standing tooth on the distal extension sides. Opposing occlusion in upper jaws was dentulous or partially edentulous where it was restored with fixed prosthesis. Selected patients were divided into two equal groups according to method of treatment plane, as follows, Group (1) Each patient in Group (1) received partial overdenture supported in free end side by an implant at second molar area with dome shaped superstructure. While; Group (2) Each patient in Group (2) received partial overdenture supported in free end side by an implant at second molar area with ball and cap attachment as a super structure. Upper and lower diagnostic cast for each patient was mounted on a semi-adjustable articulator by the aid of centric occluding relation record. Occlusion was evaluated and corrected in the patient s mouth. Surgical Procedures For Implant Installation: Trial setting up of artificial teeth in edentulous areas of mounted upper and lower casts was carried out. Acrylic surgical template was fabricated on edentulous area of lower cast. Internally hexed screwed shaped (4mm diameter- 10.5mm) titanium implants were used. Standard surgical procedures were followed for implant installation at second molar area parallel to long axis of the anterior abutment. Four months after fixture installation, the patients were recalled, and a periapical radiographs were made to confirm the absence of any radiolucency around the implant and ensure osseointegration both radiographically and clincally. A healing collar of suitable length was selected according to the thickness of the mucosa covering the implant to be projected 2mm above the mucosal surface. In group (1), dome shaped healing collar was used as a super structures. While In group (2), ball attachment was used as super structures Fig.(1,2). Fig. (1)

3 Effect of Using Attachment on Implant (3) Fig. (2) Removable Partial Denture Framework Construction: Alginate impressions in stock tray were made for all patients in both groups and poured into stone cast. Primary surveying was done to detect amount of undercut and guiding planes. Custom made perforated acrylic resin tray was constructed. Mouth preparation was done for guiding plane and occlusal rests seats site according to data gained from primary surveying. Final impression was made and poured into type 4 improved dental stone to obtain master cast. Secondary surveying was done for master casts before duplication. Partial denture design: The design for all finished partial denture was the same. The only difference was in type of distal support and retention. In group (1): The prostheses were supported only by (dome shaped) healing collar superstructure over distal placing implant. Prosthesis consider as partial overdenture where implant provide support only in distal extension area. In group (2): Partial overdenture was supported and retained in distal free end site by using ball and cab attachment as implant superstructure. The design of finished partial denture for all patients was the same. a) Occlusal rests: Occlusal rests seats were prepared in the last standing natural teeth either in form of distal occlusal rest in lower first premolar or cingulum rest in lower canine. b) Direct retainer: Aker clasp was used In case of lower first or second premolar. In case of lower canine, wrought wire clasp was used. c) Major connection: Lingual bar major connector was used. d) Denture base: A hole was made around implant site in the metal frame work. Metal frame work was tried in inside patient mouth. Wax rim was made on the metal framework, centric occluding relation was registered. Setting up of artificial teeth was carried out using low cusp angles cross linked acrylic resin teeth. Waxed partial dentures were then tried inside patient s mouth, and then processed using heat cured acrylic resin, finished and polished Fig.(3). At time of delivery the adjustment of denture to accommodate super structure of implant by creating a hole in fitting surface of denture at area of super structures. Refitting of partial denture was made by self cure Acrylic resin. Direct pick-up for cap attachment from patient mouth was done. Patients were asked to return back 24 hours after denture insertion for soft tissue inspection and doing necessary adjustment. Fig. (3) Methods of evaluation: After denture insertion the following investigations were carried out for each patient to evaluate the supporting structures of the prosthesis both biologically and radiographically. I] Biological evaluation: Follows up records (the records presented the mean of the data for each abutment) were made at time of denture delivery, six, and twelve

4 (4) Ahmed Fahmy, et al. C.D.J. Vol. 24. No. (I) months after denture delivery. 1. Loss of attachment level: The mean value of loss of attachment was anterior measured at anter abutments and fixture abutments using the sensor probe (pressure sensitive probe). The distance from the tip of the probe to a marked sign on the natural abutment and to the top of the posterior abutment was measured. II] Radiographic evaluation: Direct digital radiography using Digora system to measure the following: 1- Changes in the marginal bone height distally in the anterior abutments, distally and mesially in the posterior fixture abutments. 2- Changes in the bone density of the fixture and natural abutments in both groups. For the bone changes, the mean values of the mesial or distal surfaces of all abutments along the whole study period were calculated. The Digora imaging plate, the Rinn (XCP) periapical film holders, individually constructed radiographic acrylic templates and long cone parallel technique were used for making standardized digital images for the anterior and posterior abutments by applying the long cone paralleling technique. perpendicular to a tangent drawn to the root apex. The second and third lines were equal and parallel to the first line and were 1-mm apart. Bone density along the three lines was recorded and the mean value of the readings was calculated Fig. (4). Statistical Analysis: Statistical analysis was carried out using SAS program (SAS, 1988). Student t test (Procedure TTEST of SAS) was run to test the effect of immediate and delayed treatment on means, and changes of different measurements within each time interval. Paired t test (Procedure Means of SAS) was used to test the significance of different measurements between each two intervals as well as during the whole follow-up period within each treatment (immediate and delayed). Simple correlation coefficient (Procedure Corr of SAS) was calculated between bone height and bone density within each interval as well as between changes in bone height and bone density within each interval (SAS, 1988). i. Marginal bone height measurements (Linear analysis): The linear measurement system supplied by the special soft-ware of the Digora was used to assess mesial and distal marginal bone height around the abutment teeth and implants at the time of denture insertion and at the end of different follow up periods. The distance from alveolar crest to junction between implant and abutment or to cementoenamel junction for natural abutment was measured. 2. Densitometric analysis for the anterior natural abutment: Three lines were drawn distal to the anterior abutment. The first line extended from the crest of the alveolar ridge to the apex of the tooth passing just distal to the lamina dura parallel to the root surface and RESULTS Fig. (4) The patients who participated in this study attended all follow up periods. Regarding patient s satisfaction, patients having ball and socket abutments in group (A) were more satisfied about retention than those in group (B) having dome shape abutments.

5 Effect of Using Attachment on Implant (5) Radiographic Evaluation: 1) Bone height (mm) at natural abutment The mean values of bone height changes in group (A) were 2.14 before denture wear and 2.18 and 2.22 six and twelve months respectively after denture wear. There was a statistically no significant increase in mean bone height after six months (P= 0.138) and after twelve months (P= 0.086) (Table 1). While in group (B) it was 2.36before denture wear and 2.8 and 2.83 six and twelve months respectively after denture wear. There was a statistically non significant increase in mean bone height after six months (P= 0.092) and after twelve months (P= 0.063) (Table 1). The percentage changes in mean bone height around the teeth showed a statistically no significant difference between the two groups after 6 months (P= 0.238) and after 12 months (P= 0.358) 2) Bone height (mm) at implant abutment The mean value of bone height changes in group (A) was 1.96 before denture wear and 2.2 and 2 six and twelve months respectively after denture wear. There was a statistically significant increase in mean bone height after six months (P= 0.028). After twelve months, there was a statistically none significant increase (P= 0.762) (Table 3). While in group (B) it was 2.15 before denture wear and 2.36 and 2.26 six and twelve month respectively after denture wear. There was a statistically non significant increase in mean bone height after six months (P= 0.206) and after twelve months (P= 0.276) (Table 2). The percentage changes in mean bone height around the implants showed a statistically non significant difference between the two groups after 6 months (P= 0.726) and after 12 months (P= 0.546) Table (1): Mean differences and comparison of the bone height along different time intervals in group A and B Tooth Group (A) P-value Group (B) P-value Table (2): Mean, difference and comparison of the bone height along different time intervals in group A and B Implant Group (A) P-value 0.028* Group (B) P-value *: Significant at P 0.05

6 (6) Ahmed Fahmy, et al. C.D.J. Vol. 24. No. (I) B) Bone Density Result: 1) Bone density at natural abutment The mean values of bone density changes in group (A) were before denture wear and and six and twelve months respectively after denture wear. There was a statistically non significant increase in mean bone density after six months (P= 0.898) as well as after twelve months (P= 0.612) (Table 5). While in group (B) it was before denture wear and and 118 six and twelve months respectively after denture wear. Again there was a statistically non significant increase in mean bone density after six months (P= 0.354) and after twelve months (P= 0.351) (Table 3). The percentage changes in mean bone density around the tooth showed a statistically non significant difference between the two groups after 6 months (P= 0.617) and after 12 months (P= 0.511) 2) Bone density at implant abutment:- The mean value of bone density change in group (A) was before denture wear and and six and twelve months respectively after denture wear. There was a statistically significant increase in mean bone density after six months (P=0.029) and after twelve months (P= 0.029) (Table 4). While in group (B) it was before denture wear and and six and twelve months respectively after denture wear. There was a statistically significant increase in mean bone density after six months (P= 0.042) and after twelve months (P= 0.037) (Table 4). The percentage changes in mean bone density around the implants showed non statistically significant difference between the two groups after 6 months (P= 0.836) and after 12 months (P= 0.248) Table (3) Changes in the bone density along different time intervals in group A and B Tooth Group (A) P-value Group (B) P-value Table (4): Mean, differences and comparison of the bone density along the different time intervals in group A and B Implant Group (A) P-value 0.029* 0.029* Group (B) P-value 0.042* 0.037*

7 Effect of Using Attachment on Implant (7) Attachment level (mm): 1) Attachment level values at natural abutments The mean values of attachment level in group (A) were 4.8 before denture wear and 5.1 and 5.4 six and twelve months respectively after denture wear. There was a statistically no significant increase in mean attachment level after six months (P= 0.064) and after twelve months (P= 0.055) (Table 5). While in group (B) it was 5.3 before denture wear and 5.5 and 5.8 six and twelve month respectively after denture wear. Again there was a statistically none significant increase in mean attachment level after six months (P= 0.167) and after twelve months (P= 0.085) (Table 5). The percentage changes in mean attachment level around the teeth showed a statistically none significant difference between the two groups after 6 months (P= 0.086) and after 12 months (P= 0.087) 2) Attachment level at implant abutment: The mean values of attachment level in group (A) were 7.1 before denture wear and 7.5 and 7.8 six and twelve months respectively after denture wear. There was a statistically none significant increase in mean attachment level after six months (P= 0.058) and after twelve months (P= 0.108) (Table 6). While in group (B) it was 7.3 before denture wear and 7.5 and 7.8 six and twelve month respectively after denture wear. The same result were again revealed as a statistically none significant increase in mean attachment level after six months (P= 0.062) and after twelve months (P= 0.051) (Table 6). The percentage changes in mean attachment level around the implants showed a statistically non significant difference between the two groups after 6 months (P= 0.178) and after 12 months (P= 0.460). Table (5) Changes in attachment level along the different time intervals in group A and B Tooth Group (A) Mean difference P-value Group (B) Mean difference P-value Table (6) Changes in the attachment level along the different time intervals in group A and B Implant Group (A) Mean difference P-value Group (B) Mean difference P-value

8 (8) Ahmed Fahmy, et al. C.D.J. Vol. 24. No. (I) DISCUSSION Most problems of the free end saddle cases can be solved by improving its support and /or retention and stability through the use of implant in the distal extension area. In this study implants were used to provide support and /or retention in partial implant overdenture so all factors that could affect ossointegration either systemically or locally were considered. Moreover, all factors that control the value of forces transmitted were considered as follow, length of the span of selected patients, abnormal or small ridges were excluded, moreover, the opposing arch in all selected cases was either dentulous or partially edentulous restored with fixed prostheses to standardize the effect of opposing occlusion and their effect on the force transmission (van Gouten et al., 1986, Desjardins, 1996 and Misch 1999). Simplified and hygienic designs was considered in this study, where every component of the partial denture should have definite function, Aker clasp design was used in case of first or second premolar and in case of canine wrought wire clasp was used, as the nature of support in free end saddle area changing from tooth-tissue support to tooth implant support. The long cone paralleling technique with Individual acrylic resin template of periapical radiograph was used to measure alveolar bone height as it is considered a standard technique for measuring, Cox & Zerb; (1986), Smith & Zarb; (1989). Generally speaking Kennedy class II has a main problem of support and retention which is pushing the patients usually for comparison between the two sides, the natural and artificial one. From the patient s point of view, all were satisfied with their partial dentures especially those with ball and cap attachment. This is due to that both the attachment and dome shaped-super structure provided posterior support, preventing tissuewards movement of the free end base, moreover, the attachment added another advantages for the patients who were satisfied as it not only helped in support but also added the retention for the partial denture. Both abutments either natural teeth or implant fixtures showed both biologic and radiographic changes in the two studied groups through out one year follow up period. These changes were accepted as it could be considered as a biologic response to the insertion of the partial denture in the patients mouth regarding micro-flora and the stresses transmitted to the investing structures (El-Ghamrawy 1977; Nada et al., 1987). Theoretically speaking, increase in alveolar bone height & density means that, the bone reacts favorably to the applied force. When the natural tooth was assisted by the implant to support an overdenture, the stress waves reached the tooth through the implant and bone, as well as, directly from the overdenture, hence the natural tooth was the primary recipient of the stress so bone resorption would occur, where periodontal ligament of the natural teeth absorbs most of the stresses relieving the implants from being subjected to overloading. This explained why in the current study bone resorption seemed to be more than bone formation regarding natural abutments and resulted in decrease bone height. The fact that, this decrease in bone height was non-significant might be attributed to optimum hygienic and simple design in removable partial denture used, allowing control and dissipating forces applied on natural teeth, less plaque accumulation and more facility for proper oral hygiene and hence less gingival inflammation. These results were previously reported by Abuelross (2003). Bone resorption recorded at the distal sides of natural abutments in both groups might be attributed to lateral forces that could produce distributing stresses unevenly over the entire root surface to the alveolar bone leading to pressure or tension. Pressure occurred more on distally relative to the length of the edentulous area, while tension occurred mesially. The increase in bone height relative to the implant abutment recorded in this work agrees with the findings reported by many investigators Taylor et al Such increase in the physiologic loading of the implant side enhances bone formation and bone density. This explains why the bone height was generally increased in implant abutments compared with the natural abutments in both groups in this present study. Patients with ball and cap attachments

9 Effect of Using Attachment on Implant (9) (Group A) had nylon sheath in cap attachment and those with dome shaped superstructure of implants with no lateral walls or sharp angels (Group B) which allowed dissipating all lateral forces only vertical forces were transmitted to the long access of tooth. Moreover, the use of non-rigid method of attachment to connect the implants and the teeth may help to relieve the stresses induced in the implants Elkerdawy (2005). Regarding the changes occurring in bone density around different abutments, it was found non-significant increase in bone density for both implants and anterior abutment in both groups was formed (Group A & B). This could be attributed to proper treatment plane regarding toothimplant support, simple and efficient design of partial denture as well as proper selection of implant super structure. Statistically, both groups showed no significant difference regarding the manner of the marginal bone height changes for both types of abutments in both sides and at different time periods. This denotes that the ball attachments and the copings transmitted force within the physiologic tolerance of the anchoring bone within a one year follow-up period. SUMMARY and CONCLUSION This study was performed to evaluate the effect of using attachment on implant supported distal extension lower partial overdenture. Ten lower kennedy class II partially edentulous patients were selected to receive implant at second molar area, then patients were divided into 2 groups according to the implant superstructures either(dome shaped-or-ball and cap attachment). Patients of both groups receive removable partial denture of the same design. Patients were followed up for one year both clinically & radiogarphically. The results showed statically difference between the treatment plans. It could be concluded that Tooth-implant supported partial denture with or without attachment may be reasonable and simple solution for Kennedy class II partial denture. Ball and socket attachment could be considered as more favorable solution than the dome shaped one regarding prosthetics function and patients satisfaction. References 1. AbuElroos, E.: Proposed solution for Kennedy class I partially edentulous cases using osseointegrated implant. Doctor thesis in prosthodontics, Cairo University, Aydinlik E., Dayangac B., and Celik E.: Effect of splinting on abutment tooth movement. J. Prosthet. Dent., 49 : 477, Cox, J.F. and Zerb, G.A.: The longitudinal clinical efficiency of osseointegrated dental implants. A 3-year report. Int. J. Oral. Maxillofac. Imp Desjardins R.P.: Implants for the edentulous patient, Dent. Clin. Nor Amer., 40 : 195, El-Ghamrawy, E.: Ecologic oral changes caused by removable partial dentures. Egypt. Dent. J., 23: 23, Elkerdawy, M: Immediate versus delayed loading of overdenture implant abutments. Thesiss, Cairo university Gerald Krennmair, M.D., D.M.D, Ph D, Michael Weinlander, M.D., DMD, Martin Krainhofner, MD, DMD, Evapeihslinger, MD, DMD, PhD; Implant supported mandibular overdentures retained with ball or telescopic crown attachment, Int J prosthodont; 19 : Keltjens, H., Kayser, A., Hertel, R., Battistuzi, P.: Distalextension removable partial dentures supported by implants and residual teeth: considerations and case reports. Int. J. Oral Maxillofac. Implants. 8: 208, Masahiro TO., Yasuyuki Mat and Kiyoshis Koy: In vitro study of mandibular implant overdenture retained with ball, magnet, or bar attachment: comparasion of load transfer and denture stability. Int J Prosthodont, 16 : , Misch, C.E.: Contemporary implant dentistry. 2 nd ed. Mosby co., St. Louis, Chicago, London, Toronto, Monteith B.D.: Management of loading forces on mandibular distal-extension prostheses. Part I: Evaluation of concepts for design. J. Prosthet. Dent. 52: 673, Nada, M., Gharraphy, S. and Badawy, H.S.: A two year longitudinal study on the effect of removable partial denture design on the health of remaining teeth. Egypt. Dent. J. 33: 85, 1987

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