The International Journal of Prosthodontics, 02/2007

Chronic acid loads are an obligate consequence of the high animal/grain protein content of the Western diet. The effect of this diet-induced metabolic acidosis on bone mass is controversial. In a randomized, prospective, controlled, double-blind trial, 161 postmenopausal women (age 58.6 ± 4.8 y) with low bone mass (T score -1 to -4) were randomly assigned to 30 mEq of oral potassium (K) citrate (Kcitrate) or 30 mEq of K chloride (KCl) daily. The primary end point was the intergroup difference in mean percentage change in bone mineral density (BMD) at lumbar spine (L2 through L4) after 12 months. Compared with the women who received KCl, women who received Kcitrate exhibited an intergroup increase in BMD (±SE) of 1.87 ± 0.50% at L2 through L4 (P < .001), of 1.39 ± 0.48% (P < .001) at femoral neck, and of 1.98 ± 0.51% (P < .001) at total hip. Significant secondary end point intragroup changes also were found: Kcitrate increased L2 through L4 BMD significantly from baseline at months 3, 9, and 12 and reached a month 12 increase of 0.89 ± 0.30% (P < .05), whereas the KCl arm showed a decreased L2 through L4 BMD by 0.98 ± 0.38% (P < .05), significant only at month 12. Intergroup differences for distal radius and total body were NS. The Kcitrate-treated group demonstrated a sustained and significant reduction in urinary calcium excretion and a significant increase in urinary citrate excretion, with increased citrate excretion indicative of sustained systemic alkalization. Urinary bone resorption marker excretion rates were significantly reduced by Kcitrate, and for deoxypyridinoline, the intergroup difference was significant. Urinary net acid excretion correlated inversely and significantly with the change in BMD in a subset of patients. Large and significant reductions in BP were observed for both K supplements during the entire 12 months. Bone mass can be increased significantly in postmenopausal women with osteopenia by increasing their daily alkali intake as citrate, and the effect is independent of reported skeletal effects of K.

Bisphosphonate-associated osteonecrosis of the jaw (BONJ) is encountered predominantly in cancer populations being treated with high-dose intravenous bisphosphonates for skeletal complications such as bone metastases and secondary fracture risk. A minority of BONJ lesions have been observed in patients receiving oral bisphosphonates for management of osteoporosis or osteopenia. In this paper, the current knowledge pertaining to the incidence, definition, and signs and symptoms of BONJ is presented, followed by a discussion of the incidence and consequences of osteoporotic skeletal fracture and the use of oral bisphosphonates to mitigate fracture. The risk of BONJ appears to be very small in patients taking oral bisphosphonates. In addition, the consequences of osteoporotic fracture likely have significantly greater mortality and morbidity than BONJ. Within this context, management concepts and guidelines are presented to help the dental clinician allay concerns about BONJ expressed by patients receiving oral bisphosphonate therapy.

This study investigated the influence of internal surface treatment and margin location on the microleakage of 2 alumina-reinforced ceramic crown systems: In-Ceram (VITA Zahnfabrik) and Procera (Nobel Biocare). Full crowns were produced for each of the 2 systems (n = 24) in human premolars, with margins located in enamel and dentin, and luted with Single Bond and RelyX ARC (3M ESPE). Four internal ceramic treatments were tested: (1) aluminum oxide blasting (AO), (2) AO plus silane, (3) hydrofluoric acid etching (HF), and (4) HF plus silane. After thermal cycling, leakage was measured quantitatively. Statistical analysis (P < .05) showed higher leakage in dentin margins compared to enamel. In enamel, Procera showed greater leakage compared to In-Ceram. Generally, lower microleakage was observed for the AO plus silane treatment.

Purpose: To compare the in vitro 3-dimensional (3D) accuracy of fit of laser-scanned Computer Numeric Controlled (CNC)-milled implant titanium frameworks to that of conventional cast frameworks. Materials and Methods: Nine cast frameworks were fabricated on the mandibular master casts of 9 patients with 5 implants each following the well-established conventional fabrication technique. The frameworks were then laser scanned, and 9 CNC-milled titanium frameworks matching the outline of the conventional frameworks were fabricated. The accuracy of fit of both framework types was measured using a contact-type coordinate measuring machine and a computer program developed specifically for this purpose. Statistical analysis was done by a series of paired t tests. Results: The laser-scanned CNC-milled frameworks showed significantly less distortion along the x-axis (transversal, dx) compared with the conventional frameworks (means: 33.7µm and 49.2 µm, respectively) (P = .011). The titanium frameworks also demonstrated significantly less distortion on the horizontal plane compared with the conventional frameworks (means: 56 µm and 85 µm, respectively) (P = .012). The dy (sagittal) and dz (vertical) axes and total 3D distortion (Œ/dx2 + dy2 + dz2) showed less distortion overall in the laser-scanned CNC-milled frameworks, but this was not statistically significant (mean: 22.3 vs 35.6 µm, 13.3 vs 59.2 µm, 51 vs 114.1 µm, respectively, for y, z, and 3D distortion). Conclusion: Within the limitations of this study, fabrication of an implant-prosthodontic framework using the CNC milling technique yields a more accurate fit than the currently used cast technique. In vivo studies are needed to investigate the clinical significance of this recorded difference.

Purpose: The purpose of the study was to investigate whether oral health-related quality of life (OHRQOL) in an adult Swedish population could be explained by social attributes; individual attributes; dental status, with a special focus on the role of prosthodontics; and dental care attitudes. Materials and Methods: The study was based on responses to a questionnaire sent in 1998 to a random sample of 1,974 persons aged 50 to 75 years (66% response rate). Three factors representing various aspects of OHRQOL were set as dependent variables in multiple-regression models: oral health impact on everyday activities, oral health impact on the psychologic dimension, and oral health impact on oral function. Independent variables in the models were social attributes, individual attributes, number of teeth, denture (ie, type of denture, if present), and dental care attitudes. Results: General health in relation to age peers had the strongest association with all 3 dependent variables, followed by number of teeth and need care-cost barrier. When number of teeth was excluded, removable denture was found to covary with the dependent variables in each of the 3 regression models. Conclusion: The number of remaining teeth is more important than the type of denture in explaining OHRQOL. It is less important that a denture is fixed for those with few remaining teeth, in contrast to all others. Explanations are also found in general health and various aspects of dental care costs.

Cervicofacial emphysema is a well-known complication associated with the use of a high-speed air turbine. However, retropharyngeal emphysema or pneumomediastinum in the absence of severe trauma is rare. Immediate recognition of this phenomenon is essential to avoid life-threatening complications such as potential airway obstruction or venous air embolism. This article reports a case of gas diffusion into the mediastinum after dental preparatory treatment for a single-tooth crown. Pneumomediastinum should be considered whenever there are anamnestic data for retrosternal chest pain accompanied by dysphagia, dysphonia, or dyspnea caused by cervicofacial emphysema after dental treatment.

Purpose: Oral cancer develops frequently in older populations. In Japan, the incidence of oral and pharyngeal cancer is 9,201 per year, with such tumors accounting for 1.74% of all cancers. Although obturator prostheses play an important role in the rehabilitation of postmaxillectomy patients, clinicians sometimes experience difficulty in placing obturator prostheses in edentulous maxillae, and criteria for the objective evaluation of treatment outcome have yet to be established. The present study aimed to investigate postsurgical factors influencing the masticatory performance of postmaxillectomy patients with edentulous maxillae fitted with obturator prostheses. Materials and Methods: The extent of the hard palate defect, status of the mandibular dentition, mouth-opening distance, and maximum occlusal force were investigated, and masticatory performance was measured using a testing gummy jelly in 27 postmaxillectomy patients with edentulous maxillae fitted with obturator prostheses. The influence of these items was evaluated quantitatively, and theoretical masticatory performance for each subject was calculated using multiple-regression analysis (quantification method type 1). Results: Although average masticatory performance was almost equivalent to that of healthy, independent older patients with occlusal support classified as Eichner C, considerable individual variation was noted among subjects. The order of strength of influence on masticatory performance was identified by category weight: extent of hard palate defect > status of posterior mandibular teeth > maximum occlusal force > mouth-opening distance. A relatively high correlation (R2 = 0.78, P < .01, Pearson correlation coefficient) was evident between theoretical and actual values. Conclusion: Masticatory performance could be predicted by evaluating postsurgical factors in patients with edentulous maxillae fitted with obturator prostheses.

Purpose: This study investigated the survival of complete crowns in relation to periodontal variables on a long-term basis. Materials and Methods: A total of 1,037 complete crowns made in an undergraduate clinic for 456 patients were evaluated over an 18-year period. The study population was a mixture of periodontally affected and non-periodontally affected patients, which is comparable to the population group in a private practice. Patients were offered a supportive maintenance program. Periodontal variables were measured, including Plaque Index (PI), bleeding on probing (BOP), probing pocket depth (PPD), and attachment level. The Community Periodontal Index for Treatment Needs (CPITN) was calculated per sextant in a full-mouth assessment. Results: The estimated survival rate was 78% at year 18. For the surviving restorations, the improved PI over time was statistically significant (P = .001). Odds ratios were 1.00 for both PI and BOP. For the CPITN, odds ratios were 3.00 to 3.83. Caries was the most frequent reason for failure, followed by periodontal disease. Conclusion: PI and BOP were not directly related to the frequency of failures. Patients with a high CPITN at baseline had a 3.8 times greater likelihood of losing a complete crown (and abutment tooth) than patients with a low CPITN. The higher failure rate was related not only to periodontal disease, but also to a wide range of biologic and technical problems. In relation to complete crown survival, caution is needed in patients with a high CPITN at baseline. Prosthetic work should be preceded by periodontal examination and prophylactic and periodontal treatment if needed.

The aim of this study was to investigate the marginal precision of new chairside copings prepared on 20 extracted teeth. The marginal fit was examined micro-scopically through 360-degree external observations. Subsequently, 10 new copings were adapted in vivo on 10 teeth that were planned for extraction. After extraction, the marginal fit was evaluated using the same protocol. The mean values of the marginal gap for the 2 groups (20 and 10 copings) were 24.1 and 32.6 µm, respectively. The marginal precision of the new copings was within the clinically accepted limits.

Purpose: The purpose of this study was to investigate the relationship between self-assessed satisfaction with mastication and food acceptability and masticatory performance in a large sample of older adults with various occlusal statuses. Materials and Methods: The subjects were 708 community-dwelling, independently living elderly persons (351 men and 357 women) with a mean age of 66.0 (SD: 4.2) years. Satisfaction with masticatory function and food acceptability (apples, grilled beef, and hard rice crackers) were evaluated using questionnaires. Masticatory performance was determined using test gummy jellies developed for measuring masticatory performance. Subjects were grouped into 3 categories by posterior occlusal contacts according to the Eichner Index. The Kruskal-Wallis test and a multiple logistic regression analysis for dissatisfaction with masticatory function were conducted. Results: Overall, posterior occlusal contacts, food acceptability, and masticatory performance were associated with satisfaction with masticatory function when evaluated with bivariate analysis. Multiple logistic regression analysis showed that the number of foods that could be eaten without difficulty was the most important explanatory variable for dissatisfaction with masticatory function (P < .01). In contrast, objective masticatory performance was not significantly associated with dissatisfaction with masticatory function (P = .057) after controlling for posterior occlusal contacts and food acceptance. Conclusions: The subjective masticatory function was associated not only with objective masticatory performance, but also with an individual's posterior occlusal contacts.

Purpose: The aim of this study was to evaluate the clinical performance of all-ceramic crowns made with the IPS Empress 2 system after an observation period of 12 to 60 months. Materials and Methods: Seventy-nine IPS Empress 2 crowns were placed in 21 patients. The all-ceramic crowns were evaluated clinically, radiographically, and using clinical photographs. The evaluations took place at baseline (2 days after cementation) and at 6-month intervals for 12 to 60 months. Survival rate of the crowns was determined using Kaplan-Meier statistical analysis. Results: Based on the US Public Health Service criteria, 95.24% of the crowns were rated satisfactory after a mean follow-up period of 58 months. Fracture was registered in only 1 crown. One endodontically treated tooth failed as a result of fracture at the cervical margin area. Conclusion: In this in vivo study, IPS Empress 2 crowns exhibited a satisfactory clinical performance during an observation period ranging from 12 to 60 months.

Purpose: The aim of this prospective randomized controlled trial was to evaluate the influence of clinical baseline characteristics on the survival of 2 post systems. Materials and Methods: One hundred patients needing a post were included. Half the patients received a glass fiber-reinforced post (FRP), and the other half received metal screw posts (MSP). The posts were assigned randomly. In addition to demographic data, the following parameters were recorded: type of tooth (incisor/canine versus molar/premolar), length of the post in relation to root length (percentage), extent of coronal tooth destruction (percentage), ferrule height (in millimeters), type of restoration (fixed or removable partial denture), and presence of antagonistic contacts (yes/no). After at least 1 year (mean: 13.84 months), the patients were recalled. Statistical analysis was performed using the log-rank test and Cox regression analysis. Results: The survival rate of FRPs was 93.5%. In the MSP group, the survival rate was significantly lower (75.6%; log-rank test, P = .049). Additionally, the metal posts were associated with more unfavorable complications, for example, root fracture. The type of the tooth and the degree of coronal tooth destruction influenced the survival of MSPs, whereas no influence of these variables could be seen for FRPs. Conclusion: FRPs are superior to MSPs with respect to short-term clinical performance. Especially for MSPs, clinical survival depends on several variables.

The aim of this study was to evaluate a new type of coping used for overdentures. Twenty-nine patients received 60 new chairside copings prepared by 3 operators. The copings, used to anchor removable prostheses, were followed up for between 6 months and 4 years with inspection, probing, and radiographic evaluation. Five teeth (8.3%) were extracted. A few clinical problems occurred, including decementation, periodontal pathology (loss of support and bleeding on probing), subgingival decay, and root fracture. No differences were noted in the incidence of complications among the 3 operators. The study demonstrated the clinical predictability of the new copings.

The aim of this study was to measure differences in oral pH after subjects drank carbonated and noncarbonated acidic soft drinks. Oral pH was measured in 17 subjects at 4 oral sites with beetrode electrodes after each subject drank 50 mL of noncarbonated and carbonated blackcurrant beverages. There were no statistical differences for either beverage regarding the time taken to recover a pH of 5.5, 6.0, and 6.5. Oral pH recovered to 6.5 within 90 seconds with both drinks. The median lowest pH recorded after 30 seconds at the 4 sites for both drinks was > pH 4.9, but there was no statistical difference in the clearance between the drinks. The implication may be that carbonation is not directly responsible for the erosive potential of different beverages.

Purpose: Patients' oral health needs are estimated through dialogue and professional assessment. The concepts of need and demand are vital to studies of dental care and oral health. Need does not always lead to demand for treatment or to utilization, depending on the gatekeeping processes between need and demand and between demand and utilization. Demand must be accepted with the understanding that there is no objective need and that demand depends on the patient's opinion. In accordance with this, the need for prosthodontic treatment is highly individual and is not automatically related to oral health status, making need and demand difficult to measure in that respect. Therefore, sociodental factors should be included and evaluated in studies of need and demand for utilization of prosthodontic care. Materials and Methods: This theoretical and analytic paper focuses on the gatekeeping processes between need and demand and between demand and utilization of prosthodontic care. Results: The concept of gatekeeping refers to the social and psychologic processes that transform need into demand and demand into utilization. It implies that they are complex processes that can render great differences between demand and actual utilization. Conclusion: It is not possible to estimate a patient's needs for prosthodontic care, since there is no objective need. Demand and utilization are factors that play an important role in the gatekeeping process. These factors are dependent on the patient's opinion, which is influenced by numerous factors.

This article presents an in vitro analysis of a specific occlusal loading test on endodontically treated teeth restored with 2 different composite post materials. Individual, customized posts (IFPs) were compared to standard fiberglass posts (SFPs). The selected IFPs (standard cylindric Targis/Vectris posts) were compared to SFPs (Conic 6% Post, Ghimas). The posts were first subjected to a 3-point bending test to compare their flexural elastic properties. They were then used to restore 22 endodontically treated artificial maxillary central incisors and subjected to a specific occlusal loading simulation test. The loading test showed that IFP restorations performed better than SFP restorations. A clinical evaluation of this laboratory observation is suggested.

Purpose: The purpose of this study was to examine the effect of stress-breaking attachments at the connections between maxillary palateless overdentures and implants. Materials and Methods: Three-dimensional finite element models were used to reproduce an edentulous human maxilla with an implant-retained overdenture. Two-implant models (in the canine tooth positions on both sides) and four-implant models (in the canine and second premolar tooth positions on both sides) were examined. Stress-breaking material connecting the implants and denture was included around each abutment. Axial loads of 100 N were applied to the occlusal surface at the left first molar tooth positions. In each model, the influence of the stress-breaking attachments was compared by changing the elastic modulus from 1 to 3,000 MPa and the thickness of the stress-breaking material from 1 to 3 mm. Maximum stress at the implant-bone interface and stress at the cortical bone surface just under the loading point were calculated. Results: In all models, maximum stress at the implant-bone interface with implants located in the canine tooth position was generated at the peri-implant bone on the loading side. As the elastic modulus of the stress-breaking materials increased, the stress increased at the implant-bone interface and decreased at the cortical bone surface. Moreover, stress at the implant-bone interface with 3-mm-thick stress-breaking material was smaller than that with 1-mm-thick material. Conclusion: Within the limitations of this experiment, stress generated at the implant-bone interface could be controlled by altering the elastic modulus and thickness of the stress-breaking materials.

This study aimed to evaluate the durability of adhesion between acrylic teeth and denture base acrylic resin. The base surfaces of 24 acrylic teeth were flatted and submitted to 4 surface treatment methods: SM1 (control): No SM; SM2: application of a methyl methacrylate-based bonding agent (Vitacol); SM3: air abrasion with 30-µm silicone oxide plus silane; SM4: SM3 plus SM2. A heat-polymerized acrylic resin was applied to the teeth. Thereafter, bar specimens were produced for the microtensile test at dry and thermocyled conditions (60 days water storage followed by 12,000 cycles). The results showed that bond strength was significantly affected by the SM (P < .0001) (SM4 = SM2 > SM3 > SM1) and storage regimens (P < .0001) (dry > thermocycled). The methyl methacrylate-based adhesive showed the highest bond strength.