A patient-calibrated individual wax-up as an essential tool for planning and creating a patient-oriented treatment concept for pathological tooth wear.

Tooth wear is generally a physiological process; however, it can also be a pathological condition associated with attrition, abrasion, and erosion processes in which the quantity of tooth loss is atypical for the patient's age. Tooth substance loss often causes functional problems, symptoms of discomfort/pain, and esthetic impairments. Patients presenting this condition frequently need restorative treatment, combined with an increase in the vertical dimension of occlusion (VDO). A diagnostic wax-up (DWU) provides assistance in determining a new occlusal plane and VDO, and is a fundamental tool considering the backward planning involved in the execution of a complex rehabilitation. In cases of severe tooth wear, preventive measures must be taken. Yet, when a restorative intervention is needed, the use of a DWU, in conjunction with a mock-up, helps to achieve a predictable and satisfactory outcome. This article presents a case report of a young female patient with pathological tooth wear, related symptomatology, and esthetic complaints. Initially, a DWU and a diagnostic mock-up were created. After esthetic and functional corrections, a second DWU was generated and transferred to the patient's mouth by means of a therapeutic mock-up. This mock-up was used as a trial restoration for the pretreatment phase, to evaluate the new VDO/esthetics/function and to guide tooth preparation. Lithium disilicate (LS2) occlusal onlays were used to stabilize the VDO, and anterior LS2 and feldspathic veneers, combined with direct composite restorations, were executed to reach the planned minimally invasive result.

Análise tridimensional de elementos finitos da distribuição de tensões em implantes inclinados: uma revisão de literatura / Three-dimensional finite element analysis of stress distribution in tilted implants: a review of literature

Implantes inclinados atualmente são utilizados como uma alternativa cirúrgica e protética. Por tanto, estudos in vitro demonstram que o seu uso aumenta a concentração de tensão no osso cortical peri-implantar e questionasse se esse fator pode levar ao insucesso da reabilitação oral estética. O objetivo do presente artigo foi avaliar a informação relacionada com a influência de forças funcionais sobre a biomecânica de implantes inclinados nas reabilitações orais implantossuportadas. No intuito de investigar essa hipótese, foi realizada uma revisão da literatura e busca de informações existentes em artigos científicos indexados ao PubMed, que avaliassem o efeito da distribuição das tensões na interface osso-implante de implantes inclinados, através do método de análise dos elementos finitos. Os resultados mostraram que o uso de implantes inclinados aumenta a concentração de tensões no osso cortical peri-implantar sob simulação de cargas parafuncionais. No entanto, análises in-vitro não podem prever de forma precisa o comportamento dos tecidos biológicos. Apesar dessa limitação dos estudos, pode-se concluir que elevados picos de tensões poderiam comprometer os limites de resistência do osso cortical, podendo levar a falhas do conjunto osso-implante. Todavia, quando associados a reabilitações de próteses múltiplas, os implantes inclinados mudam sua biomecânica, favorecendo a distribuição e redução das tensões e o aumento da estabilidade das reabilitações como um todo.

Tilted implants are currently used as a surgical and prosthetic's alternative. Therefore, in-vitro studies demonstrate that their use increases the stress concentration in the peri-implant cortical bone and it wonders whether this can lead to the failure of an aesthetic oral rehabilitation. The aim of this paper was to assess information related to the influence of functional forces on the biomechanics of tilted implants in implant oral rehabilitation. In order to investigate this hypothesis, a literature review was made in scientific articles indexed to PubMed, to assess the effect of the stress distribution in the bone-implant interface of tilted implants, through the analysis of the finite element method. The results showed that the use of tilted implants increases the concentration of stresses in the peri-implant cortical bone under the simulation of parafunctional loads. However, in-vitro tests may not accurately predict the behavior of biological tissues. Despite this limitation of the study, it can be concluded that high peaks of tension could compromise the strength limits of cortical bone, leading to failure of the bone-implant joint. However, when associated with multiple rehabilitations, the titled implants change their biomechanics, favoring the distribution and reduction of tension and the increase of the stability of restorations as a whole.