BACKGROUND:Research is required to characterize peri-implant strain distribution associated with different restorative designs. OBJECTIVES:This in vitro qualitative photoelastic stress analysis aimed to compare the influence of retention modality (screw-retained or cement-retained) on strain development around implants supporting different 3-unit posterior restorative designs. MATERIAL AND METHODS:Six prosthetic restorative designs were evaluated according to retention modality and prosthetic configuration: 3 single crowns, cement-retained and screw-retained (SC-c and SC-s, respectively); 3 splinted crowns (SP-c and SP-s); and simple 3-unit bridges (SB-c and SB-s). All prosthetic units were morphologically identical. A photoelastic resin block incorporating 3 implants was mounted on a loading device that applied vertical loads of 200 N simultaneously at 3 identical loading points on each restoration to simulate chewing, occlusal clenching and deglutition. Fringe lines were photographically recorded and qualitatively analyzed after placement of the restorations and during loading. RESULTS:Screw-retained restoration with splinted crowns (SP-s) was the only design to exhibit strain in the unloaded state following placement, representing preload strain. Loading-induced strains were observed in SC-c and SC-s, with lower strain levels for SC-c than for SC-s, and in SP-c and SP-s, with lower strain levels for SP-c than for SP-s. Both configurations also exhibited crestal strains. The simple bridge (SB) designs revealed purely axial strains, with no crestal strains, regardless of retention modality. CONCLUSIONS:Retention modality appears to influence peri-implant strain development in mesiodistal and occlusogingival dimensions for 3-unit single crown and splinted crown designs. Screw-retained 3-unit splinted prostheses may generate preload strains around the unloaded implant supporting the restoration. Simple 3-unit bridge designs demonstrated the most favorable strain pattern, regardless of the retention modality.

Background: Individuals with tooth agenesis often present a significant clinical challenge for dental practitioners. This retrospective study evaluated clinical and radiological long-term functional and esthetic outcomes following restoration using primary teeth to support fixed all-ceramic prosthesis in patients with teeth agenesis. Methods: Patients with teeth agenesis and at least one year follow-up were included. Examinations included panoramic X-ray, clinical examination and family history records. Only primary teeth without permanent teeth underneath were chosen. All ceramic fixed restorations were used. All data were collected from patient files. Outcome parameters included: restoration parameters (restoration survival, restoration fractures, restoration detachment, restoration replacement, and secondary caries), plaque index, and gingival index. Results: The study included 58 porcelain restorations inserted in 25 individuals; mean age 12 ± 2.1 years (range 10–19 years); mean number of missing teeth 12.3 ± 9 (range 6–12). Mean follow-up 48 ± 6 months (range 12–60 months). All restorations survived up to last follow-up, rendering a survival rate of 100%. Restorations outcome—porcelain chipping (9%), detachment (2%), no restoration replacement nor secondary caries, mean gingival index—0.7 ± 0.5 and mean plaque index—0.9 ± 0.3. Conclusions: In tooth agenesis, restoration using primary teeth to support fixed all-ceramic prosthesis is a viable treatment alternative.

Background: Two of the most popular resilient attachment systems for mandibular implant-supported overdenture (MISOD) are locator and ball attachments. The purpose of the present retrospective cohort study was to assess the long-term prosthetic aftercare and oral hygiene status in edentulous patients rehabilitated with MISOD. Materials and Methods: Forty-five consecutive patients were included (22, group A- ball vs. 23, group B- locator attachments). Attachment incorporation into the MISOD was conducted in a direct (chair-side) intraoral technique at the time of denture insertion. Routine follow-up included yearly visits. The number of visits requiring prosthetic aftercare, either during the follow-up or during the additional visit, was recorded. Outcome parameters included—prosthetic aftercare—the number of aftercare (primary outcome parameter) visits, and dental treatment received (pressure sores relief, liner changes due to loss of retention, loss of retention due to debris accumulation, denture repair—secondary outcome parameters); oral hygiene—gingival index (primary outcome parameter). Results: The mean follow-up of the entire study population was 84 ± 21 months, range 39–120 months. Statistical analysis revealed a lower need for prosthetic aftercare interventions in group A (p < 0.001). The mean number of visits dedicated to pressure sores relief (6.09 ± 1.04 vs. 3.03 ± 0.77, p < 0.001) and liner exchange due to loss of retention (5.6 ± 1.03 vs. 2.09 ± 1.04, p < 0.001), were significantly lower in group A. Debris (food/calculus) accumulation inside the attachment was noted only for the locator’s group (p < 0.001). No statistically significant differences between the groups were noted for denture repair (p = 0.318). Oral hygiene also exhibited statistically significant differences in favor of group A (2.3 ± 0.3 vs. 1.03 ± 0.2, p < 0.001). Conclusions: It can be concluded that using ball attachments for MISOD yields less need for aftercare treatments and improved oral hygiene status over the years.

Background: Substantial effort is dedicated to finding the most favorable parameters that will ensure low aftercare demands among edentulous patients wearing mandibular implant supported overdentures (MISODs). The purpose of this retrospective cohort study was to compare prosthetic aftercare between MISOD patients with a simultaneous (group A) vs. a three-week settling in period (group B) prior to attachment incorporation. Methods: Forty-five patients enrolled in this study. Two implants per patient were placed using a two-stage implant insertion protocol. Second-stage surgery was performed after three months. All patients received ball attachments using the direct (chairside) incorporation method. Twenty-two patients received their dentures with simultaneous attachment activation and the rest—twenty-three patients—after a three-week settling in period. Patients’ files were scanned for aftercare visits. Outcome parameters included sore spot relief, attachment incorporation, and denture repair. Additionally, gingival index measurements were compared. Confounding factors included age, gender, and implant dimensions. Results: The mean follow-up for the entire cohort was 84 ± 21 months, and the range 39–120 months. The mean number of visits for group A vs. B respectively: pressure sores relieve (3.63 ± 0.84 vs. 3.71 ± 0.61, p = 0.581), liner exchange due to loss of retention (2.09 ± 1.03 vs. 2.31 ± 1.04 p = 0.487), and gingival index (1.3 ± 0.3 vs. 1.03 ± 0.2, p = 0.653) exhibited no statistically significant differences between the tested groups. No statistically significant differences between the groups were also noted for the denture repair aftercare treatments (p = 0.318) and the independent variables including age, gender, and implant length. Conclusions: Prosthetic aftercare in MISOD wearers is similar whether a simultaneous or a three-week settling in period for attachment incorporation is applied.

Marginal fit is an important clinical factor that affects restoration longevity. The accuracy of three polyvinyl siloxane putty-wash impression techniques was compared by marginal fit assessment using the nondestructive method. A stainless steel master cast containing three abutments with three metal crowns matching the three preparations was used to make 45 impressions: group A = single-step technique (putty and wash impression materials used simultaneously), group B = two-step technique with a 2-mm relief (putty as a preliminary impression to create a 2-mm wash space followed by the wash stage), and group C = two-step technique with a polyethylene spacer (plastic spacer used with the putty impression followed by the wash stage). Accuracy was assessed using a toolmaker microscope to measure and compare the marginal gaps between each crown and finish line on the duplicated stone casts. Each abutment was further measured at the mesial, buccal, and distal aspects. One-way analysis of variance was used for statistical analysis. P values and Scheffe post hoc contrasts were calculated. Significance was determined at .05. One-way analysis of variance showed significant differences among the three impression techniques in all three abutments and at all three locations (P < .001). Group B yielded dies with minimal gaps compared to groups A and C. The two-step impression technique with 2-mm relief was the most accurate regarding the crucial clinical factor of marginal fit.

Purpose: To measure the transfer of axial and nonaxial load in unsplinted fixed implant supported restoration with varying crown to implant (C/I) ratios and crown height space (CHS).Materials and Methods: A photoelastic block model was constructed. Three holes were drilled vertically in a straight line in the mid axis of the photoelastic model at predetermined locations to lengths of 12 mm. Three implants were inserted into the model. Two strain gauges were cemented onto the neck of each implant on the buccal and lingual aspects, which provided a simultaneous direct reading of strain. Four groups of cement retained restorations with C/I ratios of 1: 1; 1:1.5; 1:1.75, and 1: 2 were used. CHS were 10, 15, 17.5, and 20 mm, respectively. Fifteen static loadings were carried out simultaneously with 20 kg weights via a custom-built loading apparatus at 0 and 30 degrees to the vertical axis. Descriptive analysis consisted of mean and standard deviation of microstrain values for each group. Groups were compared by the use of the 1-way parametric analysis of variance. A P value of less than .05 was considered statistically significant.Results: Occlusal force application at 30 degrees showed a statistically significant increase in both buccal (1,588 +/- 150 vs 2,610.59 +/- 150) and palatal (64.92 +/- 7 vs 146.59 +/- 15) microstrain values as C/I ratio increased from 1:1 to 1:1.5 (P < .001). Force application at 30 degrees in cases with C/I ratio of 1:1.75 and 1: 2 resulted in fracture of the abutment screw followed by dislodgment of the crowns. Failures were noted at CHS > 15 mm. Conclusions: CHS is more significant than the C/I ratio in assessing biomechanical-related detrimental effects. Prosthetic failure occurred at CHS >= 15 mm. (C) 2011 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 69: 1934-1939, 2011

PURPOSE:The present study was designed to compare the long-term outcome and complications of cemented versus screw-retained implant restorations in partially edentulous patients.MATERIALS AND METHODS:Consecutive patients with bilateral partial posterior edentulism comprised the study group. Implants were placed, and cemented or screw-retained restorations were randomly assigned to the patients in a split-mouth design. Follow-up (up to 15 years) examinations were performed every 6 months in the first year and every 12 months in subsequent years. The following parameters were evaluated and recorded at each recall appointment: ceramic fracture, abutment screw loosening, metal frame fracture, Gingival Index, and marginal bone loss.RESULTS:Thirty-eight patients were treated with 221 implants to support partial prostheses. No implants during the follow-up period (mean follow-up, 66 ± 47 months for screw-retained restorations [range, 18 to 180 months] and 61 ± 40 months for cemented restorations [range, 18 to 159 months]). Ceramic fracture occurred significantly more frequently (P < .001) in screw-retained (38% ± 0.3%) than in cemented (4% ± 0.1%) restorations. Abutment screw loosening occurred statistically significantly more often (P = .001) in screw-retained (32% ± 0.3%) than in cement-retained (9% ± 0.2%) restorations. There were no metal frame fractures in either type of restoration. The mean Gingival Index scores were statistically significantly higher (P < .001) for screw-retained (0.48 ± 0.5) than for cemented (0.09 ± 0.3) restorations. The mean marginal bone loss was statistically significantly higher (P < .001) for screw-retained (1.4 ± 0.6 mm) than for cemented (0.69 ± 0.5 mm) restorations.CONCLUSION:The long-term outcome of cemented implant-supported restorations was superior to that of screw-retained restorations, both clinically and biologically.

Background: Bone grafting may be associated with soft and hard tissue complications. Recipient site complications encountered using cancellous block allografts for ridge augmentation are analyzed.Methods: A total of 101 consecutive patients (62 females and 39 males; mean age 44 ± 17 years) were treated with implant‐supported restoration of 137 severe atrophic alveolar ridges augmented with cancellous bone‐block allografts. Alveolar ridge deficiency locations were classified as anterior maxilla (n = 58); posterior maxilla (n = 32 sinuses); posterior mandible (n = 32); and anterior mandible (n = 15). A total of 271 rough‐surface implants were placed. Recipient site complications associated with block grafting (infection, membrane exposure, incision line opening, perforation of mucosa over the grafted bone, partial graft failure, total graft failure, and implant failure) were recorded.Results: Partial and total bone‐block graft failure occurred in 10 (7%) and 11 (8%) of 137 augmented sites, respectively. Implant failure rate was 12 (4.4%) of 271. Soft tissue complications included membrane exposure (42 [30.7%] of 137); incision line opening (41 [30%] of 137); and perforation of the mucosa over the grafted bone (19 [14%] of 137). Infection of the grafted site occurred in 18 (13%) of 137 bone blocks. Alveolar ridge deficiency location had a statistically significant effect on the outcome of recipient site complications. More complications were noted in the mandible compared to the maxilla. Age and gender had no statistically significant effect.Conclusions: Failures caused by complications were rarely noted in association with cancellous block grafting. The incidence of complications in the mandible was significantly higher. Soft tissue complications do not necessarily result in total loss of cancellous block allograft.

OBJECTIVE:The aim of this long-term study was to compare the need for prosthetic aftercare of direct vs. indirect attachment incorporation techniques to mandibular implant-supported overdenture.MATERIALS AND METHODS:Forty-five consecutive patients were included (130 implants were placed). Treatment was randomly allocated, resulting in 22 patients (group A) to be treated with direct ball attachment incorporation and 23 patients (group B) to be treated with indirect ball attachment incorporation. All patients were treated by experienced oral-maxillofacial surgeons/periodontists and experienced prosthodontists/residents. From the first day that the patients visited the clinic up to 20 years after the first treatment session, all surgical or prosthetic therapeutic interventions were recorded. The recorded data for the present study included the number of aftercare visits and dental treatment received (pressure sores relieve, liner changes due to loss of retention and attachment replacement due to wear).RESULTS:The mean follow-up was 93±57 months. No implants were lost. Statistical analysis revealed a statistically significantly (P<0.001) greater need for prosthetic interventions in group B vs. group A. The mean number of visits dedicated to - pressure sores relieve (7.04±1.4 vs. 3.63±0.84); liner exchange due to loss of retention (3.6±1.3 vs. 1.09±1.06) was significantly higher in group B. Attachment replacement due to wear occurred only in group B (11/23 - 47.8%).CONCLUSION:The direct technique for attachment incorporation in mandibular implant-supported overdentures using ball attachments is superior to the indirect technique from the aftercare perspective during a long-term evaluation period.

BACKGROUND:The present study evaluated the outcome of ridge augmentation with cancellous freeze-dried block bone allografts in the posterior atrophic mandible followed by placement of dental implants.MATERIALS AND METHODS:A bony deficiency of at least 3 mm, horizontally, vertically, or both, according to computerized tomography (CT) para-axial reconstruction served as inclusion criteria. Implants were inserted after a healing period of 6 months. Bone measurements were taken prior to bone augmentation, during implant placement, and at second-stage surgery. Marginal bone loss and crown-to-implant ratio were also measured.RESULTS:Twenty-nine cancellous allogeneic bone blocks were placed in 21 patients. The mean follow-up was 37 months. Bone block survival rate was 79.3%. Mean horizontal and vertical bone gains were 5.6 and 4.3 mm, respectively. Mean buccal bone resorption was 0.5 mm at implant placement and 0.2 mm at second-stage surgery. A total of 85 implants were placed. Mean bone thickness buccal to the implant neck was 2.5 mm at implant placement and 2.3 mm at second-stage surgery. There was no evidence of vertical bone loss between implant placement and second-stage surgery. Implant survival rate was 95.3%. All patients received a fixed implant-supported prosthesis. At the last follow-up, the mean marginal bone loss was 0.5 mm. The mean crown-to-implant ratio was 0.96.CONCLUSION:Implant placement in the posterior atrophic mandible following augmentation with cancellous freeze-dried bone block allografts may be regarded as a viable treatment alternative.

An accurate implant impression is essential for the fabrication of an accurately fitting superstructure. This is important to reduce stress in the implant components and bone adjacent to the implants. The unique implant-bone relationship requires a high standard of fit and is considered critical to the long-term success of a prosthesis. 1 Lekholm U Adell RM Brånemark PI Complications. in: Brånemark PI Zarb GA Albrektsson T Tissue-integrated prostheses: osseointegration in clinical dentistry. Quintessence, Chicago1985: 233-240 Google Scholar , 2 Rangert B Jemt T Jörneus L Forces and moments on Brånemark implants. Int J Oral Maxillofac Implants. 1989; 4: 241-247 PubMed Google Scholar , 3 Wee AG Aquilino SA Schneider RL Strategies to achieve fit in implant prosthodontics: a review of the literature. Int J Prosthodont. 1999; 12: 167-178 PubMed Google Scholar , 4 Nissan J Gross M Shifman A Assif D Stress levels for well-fitting implant superstructures as a function of tightening force levels, tightening sequence, and different operators. J Prosthet Dent. 2001; 86: 20-23 Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar

The normal bone resorption after tooth extraction can be significantly aggravated in the case of pre-existing severe bone loss and chronic infection. Bone augmentation procedures have been proposed, but they require adequate closure of soft tissues. We propose the use of intrasocket reactive tissue to cover extraction sites augmented by bovine bone mineral graft to promote the success of the graft procedure.The study included 24 patients with severe bone loss and chronic pathology in 27 sites. The intrasocket reactive soft tissue was elevated from the bony walls in a subperiosteal plane. Porous bovine or allograft bone mineral was placed in the extraction site without membranes, and the intrasocket reactive soft tissue was sutured over the grafting material to seal the coronal portion of the socket. Twenty-seven implants were placed 6 months after bone augmentation.Healing progressed uneventfully. Postoperative morbidity was minimal. There was no leakage or infection of the grafting material. The mean time to implant placement was 7.8 months. Supplemental augmentation was not needed. There were no implant failures. Follow-up ranged from 6 to 36 months (mean, 15 months). All implants were rehabilitated with fixed prostheses.Intrasocket reactive soft tissue can be used predictably to obtain primary closure of augmented extraction sites with severe bone loss with minimal postoperative morbidity.