A systematic review of CAD/CAM fit restoration evaluations.

The evolution and development of CAD/CAM systems have led to the production of prosthetic reconstructions by going beyond the use of traditional techniques. Precision adjustment of prosthetic elements is considered essential to ensure sustainable restoration and dental preparation. The purpose of this article was to summarise the current literature on the fitting quality of fixed prostheses obtained by CAD/CAM technology.

Effect of simulated masticatory loading on the retention of stud attachments for implant overdentures.

This study assessed the effect of simulated mastication on the retention of two stud attachment systems for 2-implants overdentures. Sixteen specimens, each simulating an edentulous ridge with implants and an overdenture were divided into two groups, according to the attachment system: Group I (Nobel Biocare ball-socket attachments) and Group II (Locator attachments). Retention forces were measured before and after 400,000 simulated masticatory loads in a customised device. Data were compared by two-way anova followed by Bonferroni test (α = 0·05). Group I presented significantly lower retention forces (Newtons) than Group II at baseline (10·6 ± 3·6 and 66·4 ± 16·0, respectively). However, differences were not significant after 400,000 loads (7·9 ± 4·3 and 21·6 ± 17·0). The number of cycles did not influence the measurements in Group I, whereas a non-linear descending curve was found for Group II. It was concluded that simulated mastication resulted in minor changes for the ball attachment tested. Nevertheless, it reduced the retention of Locator attachments to 40% of the baseline values, what suggests that mastication is a major factor associated with maintenance needs for this system.

Tooth extraction decision model in periodontitis patients.

OBJECTIVE: The purpose of this study was to build, around several types of input data, a decision analysis model for dental extraction strategy in periodontitis patients. MATERIALS AND METHODS: The decision analysis was based on the following scenario: a fictitious adult chronic periodontitis patient with no chief complaint, being referred to make a decision of extraction on one single tooth presenting a periodontal defect that may affect the decision-making process. A decision tree was used to identify the treatment options within the next 5 years. Scientific evidences were based on probabilities given by a literature analysis using a systematic approach. Clinical expertize was based on subjective utilities (SUs) assigned by an experts' panel. Expected utilities (EUs) were used to rank the following options: no treatment (EU(1)) or periodontal treatment (EU(2)); extraction followed by a tooth-supported fixed partial denture - FPD - (EU(3)) or an implant-supported single crown - ISC - (EU(4)). RESULTS: The robustness analysis calculation indicates that the probability of tooth survival needed to be equal to 0.78 in order that the passive option becomes optimal. However, EU(1) was impossible to calculate due to the lack of available probabilities. The EU intervals were 79-96, 86-89 and 94-95 for EU(2), EU(3) and EU(4), respectively. Consequently, the FPD option is dominated by the ISC option, and it is not possible to conclude to a difference between the periodontal and the ISC therapy. CONCLUSIONS: Within the limits of this model, tooth extraction followed by FPD is the worst strategy compared with ISC or periodontal therapies.

Testing the retention of attachments for implant overdentures - validation of an original force measurement system.

The aim of this study was to validate an original portable device to measure attachment retention of implant overdentures both in the lab and in clinical settings. The device was built with a digital force measurement gauge (Imada) secured to a vertical wheel stand associated with a customized support to hold and position the denture in adjustable angulations. Sixteen matrix and patrix cylindrical stud attachments (Locator) were randomly assigned as in vitro test specimens. Attachment abutments were secured in an implant analogue hung to the digital force gauge or to the load cell of a traction machine used as the gold standard (Instron Universal Testing Machine). Matrices were secured in a denture duplicate attached to the customized support, permitting reproducibility of their position on both pulling devices. Attachment retention in the axial direction was evaluated by measuring maximum dislodging force or peak load during five consecutive linear dislodgments of each attachment on both devices. After a wear simulation, retention was measured again at several time periods. The peak load measurements with the customized Imada device were similar to those obtained with the gold standard Instron machine. These findings suggest that the proposed portable device can provide accurate information on the retentive properties of attachment systems for removable dental prostheses.

Cost-effectiveness modeling of dental implant vs. bridge.

AIMS: We assess the cost-effectiveness of dental implant first-line strategy vs. fixed partial denture strategy in patients suffering from one single missing tooth. MATERIALS AND METHODS: The model used a simulation decision framework over a 20-year period. Potential treatment switches can occur every 5 years. Transition probabilities come from literature, epidemiological reports or expert opinions. They have been programmed using specific distribution ranges to simulate the patients' and practice variability, and to take into account parameter uncertainty. Direct medical costs have been assessed according to a cost survey. Probabilistic sensitivity analyses were conducted using 5000 Monte-Carlo simulations, generating confidence intervals of model outcomes. RESULTS: We found that mean cost-effectiveness of the bridge strategy is higher than the implant strategy. CONCLUSION: Implant as the first-line strategy appears to be the 'dominant' strategy, considering the lower overall costs and the higher success rate.

Quality of prosthetic care: patients' level of expectation, attitude and satisfaction.

The aim of this study was to compare pre-treatment level of expectation and attitude and post treatment level of satisfaction with different types of prosthetic treatment according to socio-economic and demographic factors. 162 patients attending for a prosthetic rehabilitation completed an initial questionnaire to assess their level of expectation and attitude; after completion of their treatment, a second questionnaire was mailed to evaluate the level of satisfaction. 94 answers were returned (response rate: 62%). Results showed a high level of satisfaction after all prosthetic treatment, but a significant decrease after treatment when compared to level of expectation and attitude before treatment. Statistical analysis failed to show significant differences between prosthetic treatment, but demonstrated that the place of residence or level of income variable had some influence on the level of expectations and satisfaction. In this population, it was concluded that the pre-treatment data studied had limited value in predicting the outcome of the different prosthetic treatments performed.

Socio-economic characteristics and personal attitudes of patients attending a French prosthodontic teaching clinic.

The aims of the study were to define the socio-economic characteristics of patients attending a Teaching Hospital Prosthetics Department and to determine the attitudes and aspirations of such patients. The study was performed on 162 patients who requested prosthetic treatment in a French university dental hospital department. They were asked to complete a questionnaire at the beginning of their treatment. The questionnaire was composed of 2 parts, covering respectively: firstly, social, economic, and demographic data concerning the patients, the source of referral and the primary motivation for their decision to request treatment, and secondly comments concerning their prosthetic treatment. The results show the socio-professional and socio-economic diversity of this population. In most cases, the patients were recommended to the university hospital service by their relatives or friends. Among the criteria proposed, they indicate that cost and quality of treatment were their major motivation. Analysis of the patients' comments identifies some factors responsible for the lack of efficiency associated with care and dental education.

To conserve or implant: which choice of therapy?

The longevity of teeth depends directly on the state of the periodontal tissues. Many etiologic factors can lead to the loss of a tooth. Tooth loss is frequently associated with bone resorption. The diagnosis of a condition and knowledge of its etiology are essential to assess the prognosis of the remaining teeth and to formulate the correct treatment plan. Many parameters must be investigated to ascertain an accurate diagnosis. An understanding of the patient's needs and the length and likely success of treatment guides the decision of whether to preserve teeth or extract them and place implants. Advanced periodontitis poses a major therapeutic dilemma. Judicious, strategic extractions may permit the placement of long implants in ideal positions.

In vitro study of the retention and mechanical fatigue behavior of four implant overdenture stud-type attachments.

This study sought to determine the influence of mechanical fatigue on four varieties of implant overdenture studtype attachments (Supra-Snap, O'Ring, TSIB, ZAAG). Measurements of the initial vertical retentive force and the weight of the implant abutment were recorded. The same procedure was performed after the equivalent of 2 months, 6 months, and 12 months of clinical wear. For the four attachments, weight variation of the abutment between 0 and 1,080 cycles demonstrated no significant difference. Results indicated the TSIB to be significantly most retentive; next most retentive was the O'Ring, followed respectively by Supra-Snap and ZAAG.