The International Journal of Prosthodontics, 01/2006

Purpose: The aim of this study was to assess the cytotoxicity of 4 resin composites' eluates on WEHI 13 Var fibroblasts as they aged in a biologic medium. Materials and Methods: Cytotoxicity was determined by counting the number of viable cells by trypan blue exclusion. Morphologic changes attributable to cytotoxicity were observed by May-Grunwald-Giemsa cytologic staining and microscopic examination. DNA gel electrophoresis was performed to detect possible genotoxicity and DNA damage. Results: All resin composite eluates, except that for Targis, caused a pronounced cytotoxicity during the first 72 hours that gradually decreased after 2 weeks of aging. Severe morphologic alterations and pronounced DNA damage were also observed. Conclusion: These findings indicate that resin-based dental restorative materials release agents cytotoxic and genotoxic to fibroblasts. Cytotoxicity is gradually decreased as the composite resins age in a biologic-relevant medium.

Purpose: Surgical, prosthodontic, and esthetic outcomes of conventional and immediately loaded, single, tapered, roughened-surface Southern implants in the anterior maxilla that were restored with screw-retained crowns were compared over 1 year. Materials and Methods: Standardized surgical and prosthodontic procedures were followed and accepted criteria were used for assessment. Results: There were no significant differences within or between the control and test groups for age, gender, bone quality or quantity, implant stability measurements at surgery, or implant length. Conclusion: After 1 year, the implants that had been immediately loaded with single provisional crowns at surgery and definitive crowns 8 weeks later were as successful as conventionally loaded 2-stage implants.

The purpose of this clinical study was to evaluate the effect of denture adhesive on maxillary denture performance and patient perceptions. Dentists in private practice were solicited to assist in recruitment of their own patients as subjects and to administer the study. The participating dentists recruited 194 patients (39% male, 61% female) with maxillary complete dentures. Of this population, 50.2% had a mandibular removable complete denture, 34.4% had a mandibular removable partial denture, and 15.4% had lower natural dentition and/or an implant supported prosthesis in the lower arch. The average age of the subjects was 66.6 years old, and 61.8% were currently using adhesives. The gnathometer was used to assess the subjects' anterior bite force (0 to 10 scale) to denture dislodgement before and after the application of a denture adhesive on their maxillary complete denture. Subjects were also asked to evaluate the denture performance, speaking and chewing, fit and comfort, and confidence with the adhesive versus without the adhesive as "improved," "same," or "worse". The average force of dislodgement for dentures without adhesives was 3.3 compared to 5.2 with adhesive. At least 63.4% of the subjects found an improvement in bite force with the use of the adhesive. Subjects also perceived improvement with use of adhesive as compared to without adhesive in the following areas: 79.45% in denture performance, 55.9% in speaking and chewing, 55.9% in fit and comfort, and 64.0% in confidence. Unfortunately, no data was collected on instrument reliability, and no statistical analysis was carried out on the data collected.

Purpose: The aim of this report is to summarize the efficacy of 5 experimental studies on sleep bruxism (SB) treatments using the comparative analysis "number needed to treat" (NNT) to provide an estimation of the treatment with the best possible impact. Methods: Data from 38 healthy SB subjects (21 women, 17 men; 19 to 39 years of age), recruited according to tooth-grinding history (>3 nights/week), were analyzed across 5 randomized and controlled experimental trials: bromocriptine (dopaminergic agonist), propranolol (antihypertensive), clonidine (alpha 2 cardioactive), and 2 dental splint studies (upper and MAD). SB was confirmed by a polysomnographic recording over 2 nights (1st for habituation). Sleep and SB variables were recorded and scored for 2 additional experimental nights based on similar criteria for selection of subjects and scoring of outcomes. (Lavigne, 1996). Calculations for NNT = 1 / (proportion of subjects improved with active treatment - proportion of subjects improved with control treatment); NNT lower than 4 are considered as beneficial and harmful if negative (0). The studies in the NNT comparison were homogenous since experimental designs, outcomes and selection criteria were similar (Altman, 1998; Walter, 2001). Calculations revealed that with:•Dental splint (upper), a reduction of 41.1% in the SB index was observed and NNT = 1.5•Dental splint (MAD), a reduction of 83.2% in the SB index was observed and NNT = 2.2•Clonidine, a reduction of 46.2% in the SB index was noted and NNT = 3.2•Propranolol, a very low reduction of the SB index (1.8%) and NNT = 0 •Bromocriptine, the SB index increase of 21% and the NNT was negative at -7 Results: The short-term use of dental splint was the treatment presenting the most important reduction in SB. Clonidine (1 night) had an important effect in reducing SB, although this was hampered by severe morning hypotension in 25% of subjects. Conclusion Further dose-dependant studies are needed before using clonidine in a clinical context. Research supported by: CIHR, FRSQ, CFI, Canada

Purpose: The aim of the study was to evaluate the survival rate of resin-bonded fixed partial dentures delivered between 1993 and 2003 in the Department of Prosthodontics of the University of Turin and in several private practices. Materials and Methods: The analysis took into consideration the following variables: preparations, metallic alloys, metal preparation and conditioning of the inner surfaces, isolation during cementation, type of cement, kind of prostheses, number of abutments, and number of missing teeth included in the prostheses. Results: The estimated survival probability for the first debonding or failure was 85% after 5 years and 71% after 10 years. Conclusions: The use of dental dam during cementation reduced the risk of debonding. No differences in survival rate were found for the other parameters.

Purpose: The aim of this study was to evaluate patients with severely resorbed maxillae clinically and radiographically after 2 years of routine treatment with fixed full-arch prostheses supported by bilateral zygoma implants and conventional frontal implants. Methods: The study group comprised 40 consecutive patients-24 women and 16 men aged 35 to 81 years (mean 61 years)-who had been referred during 1999 through 2003 to the clinics of Oral and Maxillofacial Surgery and Prosthetic Dentistry for treatment. The inclusion criteria for this group were patients with severely resorbed edentulous maxillae. The group underwent radiographic examinations presurgically with computerized tomography and panoramic radiographs. The implants that were installed-86 zygoma implants and 158 frontal conventional implants-were covered with oral mucosa. After the implants had been allowed to osseointegrate for 6 months, each patient was given a fixed full-arch prosthesis. All patients were radiographically and clinically documented at follow-ups of 1 month, 1 year, and 2 years. At the 2-year follow-up, the prostheses were removed and each implant was evaluated individually. Results: Prior to loading, 17 (11%) frontal implants were lost. After loading, one additional implant was lost. One zygoma implant and the fixed prosthesis it was supporting were lost during the second year and the remaining implants were left sleeping. Other complications were local mucosal swellings around zygoma abutments and sinusitis problems. Conclusion: The zygoma-implant method is a potentially valuable alternative in the rehabilitation of severely resorbed maxillae. The zygoma implant, however, would benefit from further technical development, and radiographic techniques for imaging this implant need to be refined. Soft tissue complications demand additional attention. Further clinical evaluation over longer periods of time is therefore necessary

Purpose: To evaluate the failure patterns of teeth restored with both cast metal and fiber posts after fatigue cycling. Materials and Methods: Thirty-five crownless human teeth subdivided into 5 groups were subjected to 2 3 106 100-N fatigue cycles at 8 Hz under 37°C water. Results: No root fatigue fractures were recorded. High microleakage values were found in specimens that survived fatigue. No statistically significant relationships were found for fatigue (P > .4), fracture strength (P > .8), and microleakage (P > .1). Conclusions: Cast-metal and fiber posts undergo insidious microscopic adhesive failures at similar levels. Increasing the post diameter and/or post stiffness could improve the core stabilization.

Purpose: The aim of this study was to investigate diferrences in the prevalence of depression and somatization scores in temporomandibular disorder (TMD) patients. Materials and Methods: One hundred fifty-four patients with single and/or multiple RDC/TMD diagnoses were classified into 7 groups based on Axis I criteria. Somatization and depression scores from the Symptom Checklist-90 were compared between groups. Results: The results of this investigation indicate that patients with myofascial pain and arthralgia psychologically differed from those with disc displacement. These results were in accordance with findings that support the notion that the pain induces psychologic sequelae, at least in relation to depression and somatization. Conclusion: It was concluded that psychologic factors play an important role in etiopathogenesis of TMD, as demonstrated by an increase in levels of depression and somatization in TMD patients.

Purpose: The aim of this in vivo study was to evaluate the clinical outcome of all-ceramic crowns fabricated by dental CAD/CAM GN-I (GC, Japan).Methods: A total of 125 patients were treated in 306 teeth (153 anterior teeth, 105 premolars, and 53 molars). This evaluation describes the results after a mean follow- up time of 23 months with a range from 12 to 34 months after cementation. Results: Five crowns (1 anterior tooth, 3 premolars, and 1 molar) fractured, and in all of the 5 cases the insufficient thickness of ceramic crowns was the reason for failure. Conclusion: All clinical performances of all-ceramic crowns except 5 cases were excellent. Thickness of ceramic crowns was important to prevent fracture after cementation

Purpose: This study aimed to investigate whether cognitive behavior therapy (CBT) was effective as a standard intervention for temporomandibular disorders (TMD). Materials and Methods: The subjects were 134 TMD outpatients with no history of treatment for TMD. They had pain persisting for 1 month or more and/or limited jaw movement. All patients underwent CBT. Symptom fluctuation was evaluated by a self-administered questionnaire. Results: Symptoms had disappeared and improved in 112 patients within 2 months. Conclusion: It was suggested that most TMD symptoms can be relieved only by CBT in less than 2 months without further intervention.

Purpose: The influence of the curing mode (dual vs light) and of the photopolymerization through ceramic or resin composite on the degree of remaining carbon bonds was investigated via infrared spectroscopic analysis for 1 resin cement (Calibra, Caulk/Dentsply). Materials and Methods: The 0.5-mm cement layer was photopolymerized for 40 s through the 2-mm-thick ceramic Empress 2 (Ivoclar) and Vitadur Alpha (Vident) and the laboratory-processed resin composite Sinfony (3M/ESPE). Results: The dual-cured system polymerized better than the light mode. Photopolymerization of the resin cement through the translucent materials reduced its curing efficiency in both curing modes. The resin composite induced a more negative effect than the 2 ceramics tested. Conclusion:The curing mode and photopolymerization of dual-cured resin cements through esthetic restorative materials affects the degree of remaining double carbon bonds.

Purpose: The purpose of this in vitro study was to demonstrate the dentinal tubule-occluding effect of desensitizing laser treatment on dentin surfaces using environmental scanning electron microscopy (E-SEM). Materials and Methods: Ground dentin surfaces were divided into 5 areas. Each area received a different mode of laser irradiation (low potency [LP] versus high potency [HP] and short time [ST] versus long time [LT]). Lased dentin surfaces were viewed and graded under E-SEM at 35,000 magnification. Results: The tubule closure rates of 4 different irradiation modes were as follows: LP/LT (74%) > HP/ST (70%) > LP/ST (51%) > HP/LT (46%) > control (6%). Conclusion: It was demonstrated that desensitizing laser application was an efficient treatment option for the occlusion of dentinal tubule apertures.

Most 3-dimensional (3D) finite element analyses (FEAs) simplify the cancellous bone to a block and completely ignore its trabecular structure. Thus, a 3D FEA was performed to compare the peri-implant stress distribution of a model in which the trabecular structure was accurately simulated (precise model) with that of a model with a homogenous cancellous bone component (simplified model). In contrast to the simplified model, the distribution patterns and higher stresses in the precise model may explain the overall bone resorption at the implant-bone interface in load-related implant failures. Further studies using data from the jawbone and a more detailed implant simulation are planned.

In this 2-part review series, the current uses of saliva as a diagnostic fluid are reviewed, first with a focus on known measurements of systemic conditions. In Part 2, the role of saliva to measure bone turnover with a special emphasis on osteoporosis will be discussed.

In this 2-part review series, the current uses of saliva as a diagnostic fluid are reviewed. Part 1 focused on known measurements of systemic conditions. In Part 2, the role of saliva to measure bone turnover with a special emphasis on osteoporosis are discussed.

Purpose: The aim of this study was to evaluate the effect of individually prescribed oral appliances for the treatment of obstructive sleep apnea syndrome (OSAS) on blood pressure, as well as factors influencing the efficacy. Materials and Methods: One hundred sixty-one patients (121 men and 40 women, mean age: 54.3 ± 13.7 years) diagnosed with mild to moderate OSAS (mean apnea-hypopnea index: 17.9 ± 14.1) were studied before and after insertion of a mandibular advancement device, with a mean interval of 60 days. Systolic, diastolic, and mean blood pressure was taken using an automatic blood pressure monitor (132.0 ± 16.1 mmHg, 82.1 ± 10.6 mmHg, 107.1 ± 12.9 mmHg, respectively, at baseline). Results: The patients were subdivided into 3 groups: responder, partial responder, and nonresponder, according to the difference of mean arterial pressure fall after the treatment. The systolic, diastolic, and mean blood pressure decreased significantly (P .001) (127.5 ± 15.0 mmHg, 79.2 ± 10.0 mmHg, 103.4 ± 12.0 mmHg, respectively) after the insertion of the device. The oral appliance therapy produced falls in blood pressure (4.5 mmHg, 3.0 mmHg, 3.7 mmHg, respectively). The response was significantly (P .001) correlated to baseline blood pressure. The responders (n = 70, mean blood pressure fall > 3.7 mmHg) and the partial responders (n = 46, 0 fall = 3.7 mmHg) showed significantly (P .05; analysis of variance) higher reduction in apnea-hypopnea index (69.6%, 65.9%, respectively) than that (52.5%) of nonresponders (n = 45, fall = 0 mmHg). Conclusion: These data suggest that effective oral appliance therapy for OSAS patients with hypertension can lead to a substantial reduction in daytime blood pressure.

Purpose: The aims of this report are to present the patient-based outcomes and associated clinical costs of an immediate loading protocol for mandibular overdentures in edentulous patients. Materials and Methods: Two groups of patients were selected. Thirty-five consecutively treated patients received an immediate protocol, while 42 patients treated with a conventional protocol served as a historical control. Patient-based concerns for patients in the immediate group were measured at various stages of treatment with 2 questionnaires: the Denture Satisfaction Scale and the Oral Health Impact Profile. Direct clinical and time costs over a 1-year period were estimated and deflated to 2002 Canadian dollars. Salary rates by occupation, age, and gender were used to evaluate the patients' time costs. Treatment costs were compared between the 2 groups. Additionally, incremental cost-effectiveness ratios for various stages with the immediate protocol were calculated. Results: Significant improvements posttreatment were observed with both the Denture Satisfaction Scale (Wilcoxon signed rank test, P .05) and the Oral Health Impact Profile (Friedman test, P .05). The immediate protocol was associated with higher maintenance costs, with resultant higher total costs (Mann-Whitney U test, P .05). No difference was observed in the time costs associated with the 2 protocols. Within-group analysis of costs at various stages of the immediate protocol suggested that treatment with implant-supported overdentures was more cost-effective than treatment with conventional dentures. Conclusions: This study suggests that implants in 1 jawbone lead to a substantial improvement in perceived oral health status. Furthermore, the immediate loading protocol was not cheaper than a conventional protocol.

Purpose: Fiber-reinforced composite (FRC) posts can be air-abraded to obtain good attachment to the resin cement. This study tested the effect of silica coating on the flexural strength of carbon, opaque, and translucent quartz FRC posts. Materials and Methods: Six experimental groups of FRC posts (n = 10 per group) were tested, either as received from the manufacturer or after chairside silica coating (30-µm CoJet-Sand). Results: There was no significant difference in the flexural strength of nonconditioned (504 to 525 MPa) and silica-coated (514 to 565 MPa) specimens (P > .05) (analysis of variance). The type of post did have a significant effect on flexural strength (P .05). Conclusion: Chairside silica coating did not affect the flexural strength of both carbon and quartz FRC posts.

Purpose: The knowledge of what levels of primary stability can be obtained in different jawbone regions and of what factors influence primary stability is limited. The objective of this study was to evaluate primary stability by resonance frequency analysis (RFA) measurements of implants placed according to a surgical protocol that aimed for high primary stability. The aim was also to correlate RFA measurements with factors related to the surgical technique, the patient, and implant design. Materials and Methods: A total of 905 Brånemark dental implants used in 267 consecutive patients were measured with RFA at the time of placement surgery. Results: A mean ISQ value of 67.4 (SD 8.6) was obtained for all implants. Univariate analyses with the implant or patient as unit showed higher ISQ values in men compared with women, in mandibles compared with maxillae, in posterior compared with anterior sites, and for wide-platform implants in comparison with regular/narrow-platform implants. There was a correlation between bone quality and primary stability, with lower ISQ values obtained for implants placed in softer bone. A lower stability was seen with increased implant length. A stepwise multiple regression analysis using the patient as unit showed that jaw type and gender had independent effects on primary stability. Conclusion: The results suggest that factors related to bone density and implant diameter/length may affect the level of primary implant stability. Furthermore, greater stability was observed in male than in female patients. High primary implant stability was achieved in all jaw regions, although the use of thinner drills and/or tapered implants cannot fully compensate for the effect of soft bone. The research design does not permit conclusions regarding long-term treatment outcome with implants.

Purpose: The aim of this clinical simulation study was to investigate the effect of anatomic and nonanatomic occlusal preparation design on stress distribution in different metal-ceramic crowns and tooth and bone. Materials and Methods: For the finite element analysis method, a 2-dimensional mathematical model of a mandibular second premolar tooth and its supporting tissues was used. The analysis was performed by using a structural analysis program. Four groups were designed: gold-palladium alloy/anatomic occlusal preparation (Au-Pd/A), Au-Pd alloy/nonanatomic (flat) occlusal preparation (Au-Pd/N), nickel-chromium alloy/anatomic occlusal preparation (Ni-Cr/A), and Ni-Cr alloy/nonanatomic occlusal preparation (Ni-Cr/N). A distributed type load of 400 N (total) was applied to the centric stop points on the tip of the buccal cusp and on the central developmental groove in centric occlusion to all types of restorations. Results: The results demonstrated that shear stresses in the dentin tissues and restorations in Au-Pd/A and Ni-Cr/A were similar. The shear stresses within the restorations in Au-Pd/N and Ni-Cr/N were similar. Conclusion: Anatomic occlusal preparation designs were advantageous in stress distribution in the dentin tissue. Nonanatomic occlusal preparation designs were found to be advantageous in the stress amount and distribution in the porcelain structure. Occlusal preparation designs and restorative materials showed no differences in stress distribution and amount in the pulp tissue and bone tissues.

Purpose: To compare dimensional measurements on computer images generated from data captured digitally by 3 different methods to those obtained directly from natural ears and ear casts, so as to determine the optimal method of creating a computer-generated ear image. Materials and Methods: Magnetic resonance imaging (MRI) was used to obtain 3-dimensional (3D) data images of the normal ears of 14 subjects. Computerized tomography (CT) and laser scanning (LS) were used to obtain 3D data images from stone casts of the same ears. Dimensional measurements were recorded on 2 occasions between anthropometric landmarks on the subjects' natural ears, casts of the ears, and reconstructed ear images obtained by CT, MRI, and LS. The intraclass correlation coefficients and coefficients of repeatability were calculated. The means of the 2 measurements for each of the dimensions were analyzed using 2-way analysis of variance to determine whether there were differences between the methods of data collection. Results: The intraclass correlation coefficients indicated that dimensions could be reliably measured on the natural ears, casts, and CT, MRI, and LS images. The coefficients of repeatability were all of a small magnitude in relation to the overall dimensions studied. No statistical differences existed between the various sources of data (P = .866) (ie, direct, cast, CT, MRI, and LS). Conclusion: The 3 methods of imaging have generally resulted in dimensional measurements on the reconstructed images that are similar to those of the original source. These are considered appropriate for manufacturing 3D models that can be used to fabricate a prosthesis. However, other factors may also be important, such as shape, contour, and internal form, and these require further investigation.

Purpose: This study determined the radiopacity of a group of nonmetallic posts. Materials and Methods: Four specimens were cut from 7 posts, and tooth sections were cut from extracted teeth. Radiographic images of all specimens along with an aluminum step wedge were obtained on occlusal films. Optical density readings for each specimen image were determined with a transmission densitometer. Radiopacity values were subsequently calculated as equivalents of aluminum thickness. Results: Analysis of variance revealed significant differences in radiopacity values among the posts (P .001). One nonmetallic post that was made of zirconium had a radiopacity value significantly greater than that of enamel. Another, made of glass fibers, acrylic resin, and fillers, had a radiopacity that was greater than that of dentin but smaller than that of enamel. The remaining 3 nonmetallic posts had radiopacity values lower than dentin. Conclusion: The 3 posts with radiopacity that was lower than dentin cannot be considered sufficiently radiopaque.

Purpose: The aim of this prospective comparative trial was to evaluate whether patients treated with complete dentures with lingualized occlusion (LO) exhibited more positive results than patients treated with complete dentures with bilaterally balanced occlusion (BBO). Materials and Methods: Twenty-eight completely edentulous patients, ranging in age from 60 to 82 years (mean age 70.9), consented in writing to be participants in this trial. The first 14 patients enrolled in the study protocol were treated with complete dentures with LO, and the next 14 patients were treated with complete dentures with BBO. Baseline characteristics were measured prior to the trial. Main outcome variables involved subjective outcomes of general satisfaction, ability to masticate, and stability and retention of the prostheses; these were quantified with a 100-mm visual analog scale. Objective outcomes were masticatory performance and the number of adjustments. Statistical assessments of the 2 groups were compared using multiple linear regression analysis. The baseline characteristics were analyzed by Student t test and chi-square test. Results: There were no significant differences between the groups at baseline. The height of the alveolar ridge exhibited significant correlations with masticatory performance (P = .02). The occlusal scheme exhibited a significant correlation with only the patient's retention satisfaction rating (P = .03). Conclusion: Despite limitations of this study attributed to the small sample size and lack of randomization, this pilot study found that edentulous patients fitted with complete dentures with LO experienced and expressed greater satisfaction with their denture retention. In addition, it was observed that a higher alveolar ridge resulted in greater masticatory performance.