Teaching Complete Denture Procedures to Dental Students by Conventional or Simplified Methods: A Randomized Clinical Trial.

With populations aging around the world, the need for complete dentures is likely to increase in Brazil and other developing countries, as well among low-income populations globally, making the teaching of cost-efficient techniques to dental students essential. The aim of this study was to evaluate the effectiveness of complete dentures fabricated by the simplified method in comparison to the conventional method regarding patients' oral health-related quality of life (OHRQoL) and satisfaction, dentures' functional quality, and masticatory performance of patients who were rehabilitated by dental students. From February 2016 to April 2017, final-year dental students at the Federal University of Alfenas, Brazil, were instructed to fabricate new complete dentures for 36 edentulous patients, who were randomly divided into two groups according to denture manufacturing method: simplified method or conventional method. Patients' OHRQoL and satisfaction and the prostheses quality were evaluated at one, three, and six months. Masticatory performance was evaluated at three months. The results showed there was no significant difference between the two methods regarding OHRQoL, patient satisfaction, prostheses quality, or masticatory performance (p>0.05). All aspects evaluated also remained constant for the same group (simplified method or conventional method) in all periods of evaluation (p>0.05). The study concluded that the simplified method for complete denture fabrication was able to produce protheses with functional quality and patient satisfaction comparable to those produced with the conventional method, even when made by dental students.

Effect of insertion torque on titanium implant osseointegration: an animal experimental study.

OBJECTIVE: To evaluate the effect of implant insertion torque on the peri-implant bone healing and implant osseointegration. MATERIAL AND METHODS: Bilaterally in the tibia of five adult New Zealand white rabbits, 20 implants were installed, subdivided into four groups, corresponding to two insertion torque conditions (low, < 10 Ncm vs. high > 50 Ncm) and 2 experimental periods (2 weeks vs. 4 weeks of healing). The implant insertion torque was determined by the surgical drill diameter relative to the implant diameter. Implant osseointegration was evaluated by quantitative histology (bone-to-implant contact with host bone [BIC-host], with neoformed bone [BIC-de novo], with both bone types [BIC-total], and peri-implant bone [BA/TA]). Every response was modelled over time using GEE (general estimation equation) with an unstructured variance-covariance matrix to correct for dependency between the measurements from one animal. The statistical significance level of α = 0.05 was applied. RESULTS: Significantly, more BIC-host and BIC-total were recorded for H implants compared with L implants after 2 week of healing (P = 0.010 and P = 0.0001, respectively). However, this result was no longer found for the extended healing period. Furthermore, BIC-total significantly increased over time for L implants (P < 0.00001). In contrast, the significant increase in BA/TA over time was found for H implants (P < 0.01). Finally, H insertion torque led to an increased BA/TA after 4 week of healing (P < 0.02) compared with the L insertion protocol. CONCLUSION: L insertion torque implants installed in the rabbit tibial bone osseointegrate with considerable de novo bone formation. This bone neoformation enables L implants to catch up, already during the early osseointegration stage, the initial inferior amount BIC contact compared with that of H implants. A negative impact of the created strain environment accompanying H insertion torque implant installation on the biological process of osseointegration could not be observed, at least not at tissue level.

Influence of the veneer-framework interface on the mechanical behavior of ceramic veneers: a nonlinear finite element analysis.

STATEMENT OF PROBLEM: The chipping of ceramic veneers is a common problem for zirconia-based restorations and is due to the weak interface between both structures. PURPOSE: The purpose of this study was to evaluate the mechanical behavior of ceramic veneers on zirconia and metal frameworks under 2 different bond-integrity conditions. MATERIAL AND METHODS: The groups were created to simulate framework-veneer bond integrity with the crowns partially debonded (frictional coefficient, 0.3) or completely bonded as follows: crown with a silver-palladium framework cemented onto a natural tooth, ceramic crown with a zirconia framework cemented onto a natural tooth, crown with a silver-palladium framework cemented onto a Morse taper implant, and ceramic crown with a zirconia framework cemented onto a Morse taper implant. The test loads were 49 N applied to the palatal surface at 45 degrees to the long axis of the crown and 25.5 N applied perpendicular to the incisal edge of the crown. The maximum principal stress, shear stress, and deformation values were calculated for the ceramic veneer; and the von Mises stress was determined for the framework. RESULTS: Veneers with partial debonding to the framework (frictional coefficient, 0.3) had greater stress concentrations in all structures compared with the completely bonded veneers. The metal ceramic crowns experienced lower stress values than ceramic crowns in models that simulate a perfect bond between the ceramic and the framework. Frameworks cemented to a tooth exhibited greater stress values than frameworks cemented to implants, regardless of the material used. CONCLUSION: Incomplete bonding between the ceramic veneer and the prosthetic framework affects the mechanical performance of the ceramic veneer, which makes it susceptible to failure, independent of the framework material or complete crown support.