The International Journal of Prosthodontics, 03/2009

Purpose: The aim of this study was to analyze prosthetic maintenance in partially edentulous patients with removable prostheses supported by teeth and strategic implants. Materials and Methods: Sixty patients with removable partial prostheses and combined tooth-implant support were identified within the time period from 1998 to 2006. One group consisted of 42 patients (planned group) with a reduced residual dentition and in need of removable partial dentures (RPDs) or overdentures in the maxilla and/or mandible. They were admitted consecutively for treatment. Due to missing teeth in strategic important positions, one or two implants were placed to improve symmetrical denture support and retention. The majority of residual teeth exhibited an impaired structural integrity and therefore were provided with root copings for denture retention. A few vital teeth were used for telescopic crowns. The anchorage system for the strategic implants was selected accordingly. A second group of 18 patients (repair group) wearing RPDs with the loss of one abutment tooth due to biologic or mechanical failure was identified. These abutment teeth were replaced by 21 implants, and patients continued to wear their original prostheses. The observation time for planned and repair groups was 12 months to 8 years. All patients followed a regular maintenance schedule. Technical or biologic complications with supporting teeth or implants and prosthetic service were registered regularly. Results: Three maxillary implants were lost after loading and three roots with copings had to be removed. Biologic problems included caries and periodontal/peri-implant infection with a significantly higher incidence in the repair group (P .05). Technical complications with the dentures were rather frequent in both groups, mostly related to the anchorage system (matrices) of root copings and implants. Maintenance and complications were observed more frequently in the first year after delivery of the denture than in the following 3 years (P .05). No denture had to be remade. Conclusions: The placement of a few implants allows for maintaining a compromised residual dentition for support of RPDs. The combination of root and implant support facilitates treatment planning and enhances designing the removable denture. It also proves to be a practical rescue method. Technical problems with the anchorage system were frequent, particularly in the first year after delivery of the dentures.

Purpose: The objective of this study was to assess the efficacy and safety of a minimally invasive sinus lift using an inflatable water balloon followed by bone grafting and implant placement. Materials and Methods: A total of 28 patients with a single tooth missing in the posterior maxilla underwent a water balloon sinus lift, followed by bone grafting and implant placement. Baseline bone height was 4.92 ± 1.24 mm. Implant site preparation employed a pilot drill and osteotomy followed by water balloon elevation. The mean inflated balloon volume was 0.67 ± 0.17 mL. Bio-Oss was filled under the elevated sinus membrane using a dedicated instrument. Twenty-eight total implants (diameter: 3.8 to 5.0 mm) were placed. Pre- and postoperative panoramic films or computed tomographs (optional) were taken for every case to measure and compare the results of the sinus membrane lift using a water balloon. Postoperative patient reactions including swelling, discoloration, discomfort, hematomas, and disability were recorded. Results: Successful sinus membrane water balloon lifting procedures were performed in 26 cases; two procedures were aborted due to sinus membrane perforation. A total of 26 implants were placed. The mean inflated balloon volume was 0.67 ± 0.17 mL and radiographic examination showed the mean elevated height by balloon to be 10.9 ± 2.06 mm. Computed tomography showed the bone graft distributing evenly around implants. Patients were extremely pleased with the results and needed very little medical attention after surgery. The mean follow-up was 15.9 ± 2.94 months. One implant was lost due to infection. Conclusion: The use of a water balloon to elevate the sinus membrane is a truly minimally invasive technique and is associated with very little discomfort. This method has encouraging results, is easy to learn, and is associated with low complication rates.

The aim of this study was to assess three-dimensional distortion in cast full-arch, screw-retained titanium implant frameworks. A conventional commercial laboratory one-piece casting was used implementing the lost-wax technique. Five wax patterns were fabricated on a die-stone cast poured from a plaster impression of a five-implant brass analog. A reflex microscope was used to determine the three-dimensional casting error. Significant differences were found in distortion between wax patterns and castings, which, given the need to keep within 150 µm of misfit for passivity, were larger than the wax frameworks by between 416 and 477 µm. The greatest distortion occurred at the terminal implant abutments and in the vertical dimensions, but the distortion was inconsistent, indicating its three-dimensional nature. It is doubtful whether any conventionally cast titanium framework can be made to the degree of accuracy required to fit passively on its abutments because of the multiple variables inherent in this process.

Purpose: The objective of this experimental study was to assess the efficacy and safety of a reinforced adjustable mandibular advancement appliance (MAA) on sleep bruxism (SB) activity compared to baseline and to a mandibular occlusal splint (MOS) in order to offer an alternative to patients with both tooth grinding and respiratory disorders during sleep. Materials and Methods: Twelve subjects (mean age: 26.0 ± 1.5 years) with frequent SB participated in a short-term (three blocks of 2 weeks each) randomized crossover controlled study. Both brain and muscle activities were quantified based on polygraphic and audio/video recordings made over 5 nights in a sleep laboratory. After habituation and baseline nights, 3 more nights were spent with an MAA in either a slight (25%) or pronounced (75%) mandibular protrusion position or with an MOS (control). Analysis of variance and Friedman and Wilcoxon signedrank tests were used for statistical analysis. Results: The mean number of SB episodes per hour was reduced by 39% and 47% from baseline with the MAA at a protrusion of 25% and 75%, respectively (P .04). No difference between the two MAA positions was noted. The MOS slightly reduced the number of SB episodes per hour without reaching statistical significance (34%, P = .07). None of the SB subjects experienced any MAA breakage. Conclusion: Short-term use of an MAA is associated with a significant reduction in SB motor activity without any appliance breakage. A reinforced MAA design may be an alternative for patients with concomitant tooth grinding and snoring or apnea during sleep.

Purpose: The aim of this study was to prospectively analyze the effect that the incorporation of osseointegrated implant dentistry had on the outcome of metalceramic tooth-supported prostheses that had been in situ for 5 to 10 years. Materials and Methods: The 10-year estimated (Kaplan-Meier) cumulative survival of metalceramic tooth-supported single crowns (TSCs) and metal-ceramic tooth-supported fixed dental prostheses (TFDPs) provided for all patients treated at two time periods was determined and statistically compared (log-rank test). Prostheses in group 1 (404 TSCs and 433 TFDP abutments in 189 TFDPs) were cemented between January 1989 and December 1993, with the outcome determined in 1998. Prostheses in group 2 (539 TSCs and 354 TFDP abutments in 142 TFDPs) were cemented between January 1997 and December 2001, with the outcome determined in 2006. A 500% increase in implants restored occurred between the end of group 1 and group 2 time periods. Results: For TSCs, comparison between groups showed a significantly better survival in group 2 than in group 1 for nonvital TSCs (P = .001), nonvital maxillary anterior teeth (P = .003), nonvital maxillary lateral incisors (P = .008), and nonvital premolars (P = .013). Comparison within groups showed nonvital TSCs had a significantly decreased survival compared to vital TSCs in group 1 (P .001), but not in group 2 (P = .48). Overall, the estimated cumulative 10-year survival of TSCs in group 2 was 94% ± 3%. For TFDPs, comparison between groups showed a significantly better survival for nonvital abutments in group 2 than in group 1 (P = .049). Comparison within groups showed nonvital TFDP abutments had a significantly decreased survival compared to vital TFDP abutments in group 1 (P = .001), but not in group 2 (P = .377). Overall, group 2's estimated cumulative 10-year survival for all TFDPs was 90% ± 6% and for three-unit TFDPs was 97% ± 2%. Teeth in group 2 failed less through fracture and periodontal disease than those in group 1. Conclusions: The incorporation of osseointegrated implant dentistry has resulted in a significant improvement in the survival of TSCs and TFDP abutments, nonvital and vital teeth having equivalent survivals for TSCs and TFDPs, and a decrease in supporting-tooth failure through fracture and periodontal disease.

Purpose: The aims of this article are to critique the available literature on dental implants in patients with ectodermal dysplasia (ED) syndrome and tooth agenesis, review the outcomes of implant therapy in these patients, and provide recommendations on the timing of implant placement for these patients. Materials and Methods: Searches were performed using Medline, Embase, All EBM Reviews, and Pre-Medline for articles relating to implant patients suffering from ED. Articles unrelated to the topic of dental implants in patients with ED and tooth agenesis, without abstracts, or in languages other than English were excluded. Selected articles were graded according to levels of evidence based upon guidelines set forth by the Agency for Health Care Policy and Research. Articles found to have a level of evidence of IV were excluded from this study. Results: The literature on dental implants in patients with ED and tooth agenesis was found to be scarce. No randomized controlled or case-controlled studies were found. Only 12 articles were found to satisfy all inclusion criteria. Conclusion: Implant survival rates vary between 88.5% and 97.6% in patients with ED and between 90% and 100% in patients with tooth agenesis. Implants placed in adolescent ED patients do not have a significant effect on craniofacial growth, while implants placed in ED patients younger than 18 years have a higher risk of failure.

Purpose: The aim of this study was to evaluate the short-term bone level response around immediately placed and provisionally restored implants using a platform switching concept. Materials and Methods: Twenty-two implants with a platform diameter of 5.5 mm were immediately placed in healthy maxillary sites in 22 patients. Resultant circumimplant spaces were filled with a mixture of bovine bone matrix and collagen. The implants were randomly divided into two equal groups: 11 implants connected with 3.8-mm-diameter abutments (test group) and 11 with 5.5-mm-diameter ones (control). Provisional crowns were adapted and adjusted for nonfunctional immediate placement on each implant and the final crowns were constructed 2 months later. Posttreatment assessments were carried out by an independent trained observer at the time of implant placement (baseline), at definitive prosthesis insertion, and every 6 months thereafter. These assessments included periapical radiographs, pocket probing depths (PPD), bleeding on probing (BOP), and modified Plaque Index (mPlI) on both implants and first proximal teeth. An image analysis software application was used to compare the bone crestal heights at the mesial and distal aspects of the implants. Results: The mean follow-up observation period was 25 months and all implants were judged to be successfully osseointegrated. In the test group, radiographic analysis showed an average bone reduction level of 0.30 mm (SD = 0.16 mm). This mean value was statistically significantly different (P = .005) from the average reduction in the control group (mean = 1.19 mm, SD = 0.35 mm). No differences between the two groups in PPD, BOP, or mPlI were found. Conclusion: This preliminary study suggests that immediate single implant restorations in specific maxillary sites with subsequent platform switching may provide peri-implant alveolar bone-level stability.

The objective of this study was to verify if differences in the design of internal hex (IH) and internal conical (IC) connection implant systems influence fracture resistance under oblique compressive forces. Twenty implant-abutment assemblies were utilized: 10 with IH connections and 10 with IC connections. Maximum deformation force for IC implants (90.58 ± 6.72 kgf) was statistically higher than that for IH implants (83.73 ± 4.94 kgf) (P = .0182). Fracture force for the IH implants was 79.86 ± 4.77 kgf. None of the IC implants fractured. The friction-locking mechanics and the solid design of the IC abutments provided greater resistance to deformation and fracture under oblique compressive loading when compared to the IH abutments.

This study investigated the effects of two self-adhesive resin cements on the retention of overdenture anchor posts after 30 days of aging in water. Forty caries-free human canines were randomly assigned to four test groups. Uni-Anchor posts were cemented to specimens in groups A and B with Breeze and Maxcem self-adhesive resin cements, respectively. In groups C and D, Fuji glass-ionomer cement and Fleck's zinc phosphate cement were used, respectively. Specimens were stored in distilled water at 37°C for 30 days. Each specimen was loaded in tension in an Instron universal testing machine. The maximum force required to dislodge each post was recorded. Means and standard deviations (SDs) were calculated and data were statistically analyzed with analysis of variance (ANOVA). Means and SDs were 706.5 ± 204.6 N for Breeze, 585.1 ± 213.5 N for Maxcem, 449.2 ± 181.1 N for Fuji, and 330.4 ± 120.6 N for Fleck's. ANOVA revealed significant differences among the means (P .0003). Adhesive failure was observed with all groups except group A, in which eight specimens underwent a cohesive fracture of the dentin. Breeze cement (group A) resulted in the highest retention force and most frequent cohesive failure and thus would be expected to clinically perform in a superior manner.

This study was designed to measure and compare the smile arcs (tooth and lip arcs) of young Caucasian and Korean subjects. Two hundred subjects (100 male and 100 female) were selected from Caucasian and Korean students. Class photographs taken with a digital camera showing the subjects with a posed smile were used for this study. Curves were rendered as semitransparent overlays, which were manipulated over the images using Adobe Photoshop to determine the best fit for tooth and lip arcs. There were statistically significant differences due to ethnicity and gender. Mean lip arcs had greater curvature than mean tooth arcs.

This clinical report presents a novel approach that integrates a new optical digitizing (scanning) technique, a three-dimensional ocular prostheses database, and the Selective Laser Sintering technique to achieve the computer-aided design and manufacture of an orbital prosthesis. An optical-structured light scanner was used to develop a color digital model of the unaffected orbital contour, which was copied and then mirrored to generate the orbital prosthesis contour data. The ocular prostheses database was applied to ascertain the size and position of the eyeball within the orbital prosthesis. Then, a Selective Laser Sintering machine directly manufactured the wax pattern of the definitive orbital prosthesis from the three-dimensional orbital data. This new approach is time and cost-effective and can be considered an alternative to traditional manual techniques of creating facial prostheses.

Purpose: The accuracy of dental impression taking is one major factor influencing the fit of crowns and fixed partial dentures. The aim of this study was to determine the accuracy of three-dimensional (3-D) tooth surface and subgingival tooth surface reproduction using three different silicone materials and the two-stage putty-and-wash technique. Materials and Methods: From 24 probands, three impressions each were taken with Express STD Putty/Wash (3M ESPE), Optosil/Xantopren L (Heraeus Kulzer), and an experimental ultralight body/putty material (3M ESPE) in a randomized order. The preliminary impression was cut according to established procedures for the twostage putty-and-wash technique. Master casts were manufactured with a standardized procedure and optically digitized. The 3-D accuracy was analyzed with a computer-aided procedure. The Express STD putty-and-wash impressions were used as a reference. Linear models were used for the statistical analysis. Results: Mean deviations of 27.0 µm and -23.6 µm were found for Optosil/Xantopren L and 26.5 µm and -22.6 µm for the experimental material when analyzing 3-D surface reproduction. The tooth surface (buccal/oral) significantly influenced the accuracy of the surface reproduction. Optosil/Xantopren L showed a more complete reproduction of the subgingival tooth surface than either the experimental or reference materials. Conclusion: The accuracy of the 3-D tooth surface reproduction as well as the reproduction of the subgingival tooth surface was not favorably influenced when the ultralight wash material was used with established cutting procedures for the preliminary impression.

Purpose: Chronic oral and dental infections that may remain benign and asymptomatic in healthy individuals can develop into serious and life-threatening conditions when leukemia patients undergo chemotherapy. There is a general consensus that elimination of chronic dental and oral infections prior to chemotherapy reduces the risk of serious problems that may require hospitalization. The limited time available for dental treatment prior to chemotherapy forces clinicians to prioritize. The aim of this study was to determine how hospital-based clinicians who routinely see leukemia patients prioritize dental treatment prior to chemotherapy. Materials and Methods: A survey was conducted that targeted the membership of the American Academy of Maxillofacial Prosthetics because a large number of these clinicians had first-hand experience in managing leukemia patients. Results: The consensus was that apical radiolucencies and severe periodontitis must be eliminated. Opinions differed regarding whether and how mild periodontal pathology and caries lesions should be treated. Conclusion: Most of the surveyed practitioners believed that infectious processes that invade the bone pose the highest risk if left untreated prior to chemotherapy.