ABSTRACT
PURPOSE: The aim of the present study was to evaluate, by means of strain gauge analysis, the effect of different implant angulations on strains around two implants retaining mandibular overdenture with Locator attachments. MATERIALS AND METHODS: Four duplicate mandibular acrylic models were constructed. Two implants were inserted in the canine regions using the following degrees of distal inclinations: group I (control); 0°, group II; 10°, group III; 20°, and group IV; 30°. Locator pink attachments were used to connect the overdenture to the implants and Locator red (designed for severely angled implants) was used for group IV (group IV(red)). For each group, two linear strain gauges were attached at the mesial and distal surfaces of the acrylic resin around each implant. Peri-implant strain was measured on loading and non-loading sides during bilateral and unilateral loading. RESULTS: For all groups, the mesial surfaces of the implants at loading and non-loading sides experienced compressive (negative) strains, while the distal implant surfaces showed tensile (positive) strains. Group IV showed the highest strain, followed by group III, group II. Both group I and group IV(red) showed the lowest strain. The strain gauges at the mesial surface of the loading side recorded the highest strain, and the distal surface at non-loading side showed the lowest strain. Unilateral loading recorded significantly higher strain than bilateral loading. CONCLUSION: Peri-implant strains around two implants used to retain mandibular overdentures with Locator attachments increase as distal implant inclination increases, except when red nylon inserts were used.
Subject(s)
Denture, Overlay , NylonsABSTRACT
Objectives: Biomechanics is one of the main factors for achieving long-term success of implant supported prostheses. Long-term failures mostly depend on biomechanical complications. It is important to distinguish the effects of macro design of the implants. Materials and Methods: In this study, the photoelastic response of four different types of implants that were inserted with different angulations were comparatively analyzed. The implant types investigated were screw cylinder (ITI, Straumann AG, Basel, Switzerland), stepped cylinder (Frialit2, Friadent GmbH, Manheim, Germany), root form (Camlog Rootline, Alatatec, Wilshelm, Germany), and cylindrical implant, with micro-threads on the implant neck (Astra, AstraTech, Mölndal, Sweden). In the test models, one of the implants was inserted straight, while the other one was aligned mesially with 15° angles. The superstructures were prepared as single crowns. A 150N loading was applied to the restorations throughout the test. Results: A comparison of the implant designs showed that there were no significant differences between the straight implants; however, between the inclined implants, the most favorable stress distribution was seen with the stepped cylinder implants. The least favorable stress concentration was observed around the root formed implants. Microthreads around the implant neck appeared to be effective in a homogenous stress distribution. Observations showed that misaligned implants caused less stress than straight implants, but the stress concentrations were not homogenous. Conclusion: As there were observable differences between the implant types, straight placed cylindrical implants showed better stress distribution characteristics, while inclined tapering implants had better stress distribution characteristics.
Subject(s)
Biomechanical Phenomena/instrumentation , Biomechanical Phenomena/methods , Dental Implants , Dental Implant-Abutment Design/methods , Dental Porcelain , Dental Prosthesis Design , Dental Prosthesis Retention/instrumentation , Dental Prosthesis, Implant-Supported , Dental Stress Analysis/instrumentation , Dental Stress Analysis/methods , Stress, MechanicalABSTRACT
A Implantologia contemporânea, associada à prótese dentária, oferece alternativas diversificadas e muito bem fundamentadas para a resolução das mais variadas e críticas situações clínicas dentro da Odontologia. Essas situações tendem, naturalmente, a agrupar-se em classificações já amplamente estudadas e consagradas na literatura mundial, considerando-se, inclusive, a importância de resultados continuamente revelados por evidências científicas nesse amplo contexto. Dentro de limites muito bem definidos, é factível a indicação e possibilidade do reaproveitamento de implantes desfavoravelmente instalados, como ponto de partida para um outro planejamento protético. Realizar nova cirurgia para removê-los e, em seguida, instalar implantes em posições supostamente ideais, com os recursos que dispomos hoje, pode até ser mais lógico ou recomendável, mas nem sempre é tecnicamente possível sem que procedimentos mais complexos sejam requisitados, acarretando maior desconforto, morbidade e tempo total para finalização. Considerar todos os aspectos possíveis que possam envolver o paciente e o problema apresentado, aliado à coerência de uma conduta mais conservadora no planejamento de qualquer tratamento, faz com que o arrojo e a impetuosidade inerentes ao conhecimento das técnicas inovadoras ou de vanguarda, ainda que consagradas, mesclem-se providencialmente com a prudência e um calibrado comedimento no campo interpretativo dos tratamentos, resultando em grandes benefícios para os pacientes. Este artigo relata um caso que ilustra essa conjunção analítica de expectativas. Reúne ciência, consciência e experiência. Funde teoria e prática, aliadas ao bom senso e previsão de bom prognóstico.
The contemporary implantology associated with dental prosthesis, provide various and very well substantiated alternatives for the resolution of the most varied and critical situations in the dental clinics. These conditions, naturally tend to be grouped into classifications extensively investigated and already enshrined in the international literature, considering, inclusively the importance of the results continuously revealed by scientific evidence in this larger context. Within very well defined limits, it is feasible and possible the indication of reutilization of previously unfavorable installed implants, as the starting point for another prosthetic planning. Further surgery to remove them and later install implants into supposedly ideal positions considering the resources available today, it may even be more logical or recommended, but not always technically possible, without having complex and undesirable procedures being required, adding greater discomfort, morbidity, taking longer for finalization. Considering all possible aspects which may involve the patient and the problem presented, together with the consistency of a more conservative approach in the planning of any treatment, causes the boldness and impetuosity inherent to knowledge of the innovative and cutting-edge, yet consecrated techniques that merge providentially calibrated with prudence and restraint in the field of interpretive treatments, resulting in significant benefits for patients. This article reports a case that illustrates this combination of analytical expectations. It brings together science, consciousness and experience. It merges theory and practice, combined with the expectation of good sense and good prognosis.