The International Journal of Prosthodontics, 06/2006

Purpose: This study aimed to clarify the relationship between oral function and Body Mass Index (BMI) using data from independently living, relatively healthy older people. The hypothesis was that oral function is more important than dental status for healthy body weight. Materials and Methods: The subjects were community-dwelling, independently living elderly people over 60 years of age (N = 807, 408 men and 399 women). An oral health examination, an oral and general health interview, and measurement of oral function, such as masticatory performance and occlusal force, were carried out. BMI (kg/m2) was used to measure body fat. A multiple logistic regression analysis was used for 2 outcome variables of underweight and overweight. Results: Overall, 70.1% of the subjects were in the normal category of BMI (20 to 25), 13.4% were in the underweight category (< 20), and 16.5% were in the overweight category (> 25). Neither occlusal force nor masticatory performance was significantly correlated with BMI. However, when the lowest 20% of occlusal force and masticatory performance values were used as explanatory variables, multiple logistic regression analyses showed that being underweight was significantly associated with having lower masticatory performance (odds ratio = 2.0, P = .015). In addition, being overweight was significantly associated with lower occlusal force (odds ratio = 1.8, P = .013). There was no statistical difference in the underweight or overweight proportions as a function of either number of teeth or type of dentition. Conclusion: Based on the results of this study, occlusal force and masticatory performance, rather than number of teeth or type of dentition, may play an important role in maintaining a normal BMI in independently living older Japanese people.

This in vitro study compared the effect of glazed and polished dental ceramic on the wear of human enamel. Five ceramics were tested under standard load after 150,000 and 300,000 simulated chewing cycles. Wear was determined from collected digital data and analyzed before and after loading. Statistical comparisons were analyzed. Polished ceramics produced less enamel wear. The amount of enamel wear for opposing IPS Empress ceramic was significantly higher (P < .001) than wear provoked by the other ceramics. The enamel wear rate was higher at the first 150,000 cycles, and polishing increased ceramic roughness, except for the IPS Empress ceramic. Polishing of dental ceramics at the contact area produces less antagonistic enamel wear.

Purpose: The objective of this experimental study was to compare the effect on sleep bruxism and tooth-grinding activity of a double-arch temporary custom-fit mandibular advancement device (MAD) and a single maxillary occlusal splint (MOS). Materials and Methods: Thirteen intense and frequent bruxors participated in this short-term randomized crossover controlled study. All polygraphic recordings and analyses were made in a sleep laboratory. The MOS was used as the active control condition and the MAD was used as the experimental treatment condition. Designed to temporarily manage snoring and sleep apnea, the MAD was used in 3 different configurations: (1) without the retention pin between the arches (full freedom of movement), (2) with the retention pin in a slightly advanced position (< 40%), and (3) with the retention pin in a more advanced position (> 75%) of the lower arch. Sleep variables, bruxism-related motor activity, and subjective reports (pain, comfort, oral salivation, and quality of sleep) were analyzed with analysis of variance and the Friedman test. Results: A significant reduction in the number of sleep bruxism episodes per hour (decrease of 42%, P < .001) was observed with the MOS. Compared to the MOS, active MADs (with advancement) also revealed a significant reduction in sleep bruxism motor activity. However, 8 of 13 patients reported pain (localized on mandibular gums and/or anterior teeth) with active MADs. Conclusions: Short-term use of a temporary custom-fit MAD is associated with a remarkable reduction in sleep bruxism motor activity. To a smaller extent, the MOS also reduces sleep bruxism. However, the exact mechanism supporting this reduction remains to be explained. Hypotheses are oriented toward the following: dimension and configuration of the appliance, presence of pain, reduced freedom of movement, or change in the upper airway patency.

This retrospective study aimed to investigate whether a mandibular implant-retained overdenture designed to counteract the rotation of the denture might influence the clinical outcome, as evaluated through the prosthetic maintenance interventions. The amount of repairs and relines of the mandibular and maxillary dentures required in an experimental group (6 patients wearing an implant-retained overdenture with a metal frame counteracting the rotation) and a control group (6 patients wearing an implant-retained overdenture allowing the rotation) was compared. Both mandibular and maxillary dentures needed few repairs or relines. The 2 types of dentures showed a similar number of maintenance interventions.

Purpose: The detrimental effect of cigarette smoking on implant survival has been previously demonstrated. The purpose of this study was to retrospectively investigate the effect of smoking on marginal bone loss around endosseous dental implants. Materials and Methods: The sample consisted of 767 Brånemark implants placed in 235 patients between 1979 and 1999. Bone level changes were determined using periapical radiographs taken at annual recall visits for 1 to 20 years following prosthesis insertion. Nonparametric tests and multiple linear regression were used to determine the influence of various factors on peri-implant bone loss during the first year of clinical loading and for all subsequent years. Results: The mean annual bone loss was 0.178 mm ± 0.401 during the first year of clinical loading and 0.066 mm ± 0.227 per year thereafter. A positive smoking history was associated with a higher rate of peri-implant bone loss, and the majority of implant failures were observed in this group of patients. Smoking at the time of stage 1 surgery did not appear to predispose implants to more marginal bone loss. Conclusion: Cigarette smoking should not be an absolute contraindication for implant therapy; rather, long-term heavy smokers must be informed that they are at a slightly higher risk of late implant failure and are susceptible to more marginal bone loss over the long-term, irrespective of their smoking status at the time of implant placement.

Purpose: This study of 3-unit fixed partial dentures (FPDs) evaluated the long-term efficacy and determined the frequencies and causes of failures. Materials and Methods: A total of 134 FPDs made in an undergraduate university clinic for 98 patients were evaluated over a 20-year period. All patients were offered a supportive maintenance program. Failures of the FPDs were divided into irreversible (loss of FPDs) or reversible (FPDs intact after conservative treatment) complications and into biologic and technical/patient-related failures. Results: The overall survival rate was 73.1% after 20 years. There was a statistically significant difference (P = .036) between the survival rates in the mandible for the vital group (96.3%) versus the root canal-treated group (69.3%). Comparing the survival rate in the vital group for the restorations in the maxilla (70.2%) versus the mandible (96.3%), a statistically significant difference (P = .045) was found. The survival rate after 20 years for the 3-unit FPDs (73.1%) was significantly different from that of the FPDs with more than 3 units (61.5%) (P = .026). The main reason for failure was caries (38.1%). Conclusion: The survival of 3-unit FPDs over a 20-year period is favorable and should be compared with other single-tooth replacement treatment options. There is an indication that the occurrence of a reversible complication has a predictive value for an irreversible complication later on.

This in vivo pilot methodologic study used 3 patients to investigate load transfer in mandibular implant-retained overdentures anchored in 2 different ways: allowing (gap condition) and counteracting (contact condition) free rotation. Load cells and strain-gauged abutments were used to evaluate occlusal load, load transmitted to the nonworking-side mucosa, and stress on the working-side abutment, in both contact and gap conditions. The occlusal load was reduced and load was shifted from abutments to mucosa in the gap versus the contact condition. In the contact condition, patients reported more comfort and felt that they could exert greater occlusal force.

Purpose: This pilot clinical trial evaluated the clinical behavior of 3-unit inlay fixed partial dentures (IFPDs) made of the glass-fiber composite system SR Adoro/Vectris and luted with 2 different bonding systems over an observation period of 2 years. Materials and Methods: Thirty-nine glass-fiber-reinforced composite IFPDs were made to replace 1 missing maxillary or mandibular tooth. Nineteen IFPDs were randomly assigned to group A and luted with a 2-step bonding system (Excite DSC), while the other 20 IFPDs of group B were cemented with a 3-step adhesive (Syntac). Events such as partial or total debonding of the IFPDs, fracture of the framework, or veneer and fiber exposures were considered failures. Color match, marginal discoloration, secondary caries, marginal adaptation, postoperative sensitivity, and surface texture were evaluated according to the United States Public Health Service modified criteria. Results: Two debondings and 2 fiber exposures occurred during the observation period. All failures occurred in group A. Some fatigue microcracks in the pontic area of the 2 detached IFPDs were observed under scanning electron microscopy. The postoperative sensitivity of group A was much higher than that of group B, and the abutments luted with Excite DCS showed postoperative sensitivity during the first month in 42.2% of cases. The sensitivity disappeared completely after 6 months. Statistical analysis indicated significant differences in postoperative sensitivity (P < .05) between the 2 groups. Conclusion: The IFPDs bonded with a 3-step adhesive demonstrated good clinical service in the short observation period. The microfractures of the layering material observed on the debonded IFPDs may suggest excessive flexibility of the fiber structures, which occurs if the framework is fabricated without observing the recommended dimensions.

Purpose: This study aimed to evaluate the clinical effectiveness of different implant sizes (8- and 10-mm lengths with 3.75-, 4.1-, and 4.8-mm diameters) in diverse host bone sites in a selected sample of partially and completely edentulous patients. Materials and Methods: Over a 14-year period, 129 patients (68 women and 61 men) were consecutively treated with a fixed prosthesis (single or multiunit, screw or cement retained) supported by 265 different-sized implants (154 standard 10-mm; 111 shorter 8-mm). Two types of implants were used (141 titanium plasma-sprayed and 124 Sand-blasted, large-grit, acid-etched). Results: Dropouts were recorded for 23 patients with 23 prostheses supported by 42 implants. In the remaining 106 patients (223 implants), 8 implants failed (4 standard and 4 shorter), in type 3 or 4 bone. Mean marginal bone loss and gingival crevice probing depth associated with either implant length were statistically comparable (P > .05). The 14-year cumulative survival rates for all short and standard implants were 97.9% and 97.1%, respectively. Survival rates were 92.3% and 95.9% for titanium plasma-sprayed short and standard implants, respectively, and 100% and 98.5% for the Sand-blasted, large-grit, acid-etched short and standard implants, respectively. Six of the 8 lost implants required implant replacement after the host sites' healing period. The remaining 2 lost implants were managed by converting the distal unit of the fixed partial prosthesis to a cantilever. Conclusion: Within the limits of the study design and observation period, a mix of implant sizes did not appear to compromise the effectiveness of implant therapy in this particular population group.

Purpose: The purpose of this study was to investigate whether application of permanent silicone-based resilient denture liner (SR) to mandibular complete dentures significantly improves patients' masticatory ability compared to conventional heat-activated acrylic resin (AR). Materials and Methods: Twenty-eight edentulous patients were randomly placed into 1 of 2 crossover groups (AR-SR/SR-AR) by using a random permuted block within strata method. The AR-SR group received AR denture treatments followed by SR denture treatments. The SR-AR group received treatments in the reverse sequence. The outcomes were classified by matiscatory performance, mandibular movement, electromyographic activity, and maximum occlusal force. Results: No significant differences were observed in any of the baseline characteristic measurements between groups. SR denture wearers exhibited significantly higher masticatory performance than AR denture wearers. SR denture wearers exhibited a longer early-stage occluding period than AR denture wearers. There were no differences in electromyographic activity between the AR and SR groups. There were no significant differences in maximum occlusal force between the AR and SR groups. Conclusion: This study showed that the application of SR to mandibular complete dentures resulted in significant improvements to the patients' masticatory ability compared to AR.

Purpose: The aim of this study was to identify the effects of tooth wear on patients' quality of life and satisfaction with their dentition. Materials and Methods: Seventy-six tooth wear patients and 76 control subjects were recruited for the study. A Dental Impact on Daily Living questionnaire was used to assess the affect of tooth wear on daily living and satisfaction with the dentition. An ordinal scale was used to assess the severity of tooth wear in a patient cohort. Results: The results showed that tooth wear has a measurable impact on patients' satisfaction with their appearance, pain levels, oral comfort, general performance, and chewing and eating capacity (P < .001). Conclusion: Tooth wear has an impact on patients' satisfaction with their dentition regardless of tooth wear severity or personal factors.

This study aimed to evaluate the influence of cement thickness on the bond strength of a fiber-reinforced composite (FRC) post system to the root dentin. Eighteen single-rooted human teeth were decoronated (length: 16 mm), the canals were prepared, and the specimens were randomly allocated to 2 groups (n = 9): group 1 (low cement thickness), in which size 3 FRC posts were cemented using adhesive plus resin cement; and group 2 (high cement thickness), in which size 1 FRC posts were cemented as in group 1. Specimens were sectioned, producing 5 samples (thickness: 1.5 mm). For cement thickness evaluation, photographs of the samples were taken using an optical microscope, and the images were analyzed. Each sample was tested in push-out, and data were statistically analyzed. Bond strengths of groups 1 and 2 did not show significant differences (P = .558), but the cement thicknesses for these groups were significantly different (P < .0001). The increase in cement thickness did not significantly affect the bond strength (r2 = 0.1389, P = .936). Increased cement thickness surrounding the FRC post did not impair the bond strength.

This study aimed to compare the fracture resistance of galvano-ceramic crowns with metal-ceramic crowns cemented to natural premolar teeth with different luting cements. Sixty intact maxillary premolars were prepared to receive full-coverage crown restorations and were divided into 2 equal groups (n = 30): galvano-ceramic crowns and metal-ceramic crowns. Each group was further subdivided into 3 equal subgroups (n = 10) according to the luting cement used: zinc-phosphate, glass-ionomer, or adhesive-resin cement. The specimens were then compressively loaded until failure in a universal testing machine. The metal-ceramic crowns exhibited higher resistance to fracture compared to galvano-ceramic crowns, but both exceeded the normal documented values of occlusal masticatory forces.

Purpose: To compare a developmental indirect resin composite with an established, microfilled directly placed resin composite used to restore severely worn teeth. The cause of the tooth wear was a combination of erosion and attrition. Materials and Methods: Over a 3-year period, a total of 32 paired direct or indirect microfilled resin composite restorations were placed on premolars and molars in 16 patients (mean age: 43 years, range: 25 to 62) with severe tooth wear. A further 26 pairs of resin composite were placed in 13 controls (mean age: 39 years, range 28 to 65) without evidence of tooth wear. The material was randomly selected for placement in the left or right sides of the mouth. Results: Sixteen restorations were retained in the tooth wear group (7 indirect and 9 direct), 7 (22%) fractured (4 indirect and 3 direct), and 9 (28%) were completely lost (5 indirect and 4 direct). There was no statistically significant difference in failure rates between the materials in this group. The control group had 21 restorations (80%) that were retained (10 indirect and 12 direct), a significantly lower rate of failure than in the tooth wear patients (P = .027). Conclusion: The results of this short-term study suggest that the use of direct and indirect resin composites for restoring worn posterior teeth is contraindicated.

The aim of this pilot study was to measure the heat transfer capacities of heat-polymerizing, injection-molded, and autopolymerizing acrylic resins in vivo. Two volunteers used acrylic resin removable plates and consumed hot (69°C) and cold drinks (6°C). Differences between oral temperature and highest and lowest temperature readings were recorded. Temperature changes for the autopolymerizing acrylic resin were found to be significantly higher than the heat-polymerizing and injection-molded acrylic resins for both cold and hot drinks. Despite the disadvantages of autopolymerizing acrylic resins, their high heat transfer capacity may be an advantage.

Purpose: The aim of this cross-sectional study was to profile complete denture wearers in 2 different unmatched and nonrandomized population groups and compare any possible relationships between the prevalence of denture stomatitis and other factors involved in wearing complete dentures. Materials and Methods: Denture wearers who attended the clinics of the Dental School and Hospital, University of Bristol, United Kingdom (group A), and the Dental School, University of Athens, Greece (group B), were examined. The examination included a record of gender, age, years wearing a complete denture, number of dentures used, duration of current denture's usage, daily time period of denture wearing, and clinical examination of the maxillary denture-bearing mucosa. Data were analyzed using the chi-square test. Results: Denture wearers of group A were older, more experienced in wearing complete dentures, and had used more sets of dentures. The majority of patients used dentures exhibiting decreased vertical dimension of occlusion and wore their dentures only in the daytime. Denture stomatitis prevalence was statistically significantly different between groups A and B (27% and 39.7%, respectively). In both groups, the denture stomatitis prevalence was greater in women. There was no statistically significant difference between the groups regarding the age of denture wearers, the number of dentures used, or the vertical dimension of occlusion. In group B, the denture stomatitis prevalence was significantly related to the years of denture- wearing experience and the current denture's usage. In both groups, continuous denture wearing was highly related to denture stomatitis prevalence. Conclusions: This cross-sectional study showed that 2 different population groups of denture wearers presented different complete denture wearing habits and denture stomatitis prevalence. Comparisons indicate that proper denture wearing habits decrease the prevalence of denture stomatitis.