Three-Dimensional Finite Element Analysis of Stress Distribution in Zirconia and Titanium Dental Implants.

Zirconia has been presented as an alternative biomaterial to titanium, commercially presented as a single-body implant and/or as an abutment, demonstrating clinically biocompatible favorable results in white and rose esthetics. However, the number of long-term in vivo studies and mechanical tests evaluating the response of stress distribution compared with titanium implants is still limited. The aim of the study was to compare the principal peak stresses in the peri-implant bone around titanium and zirconia implants using the finite element method. Four groups of 3-dimensional models were constructed for the tests: G1, external hexagon titanium implant with a zirconia abutment; G2, zirconia implant with a zirconia abutment; G3, single-body titanium implant; and G4, single-body zirconia implant. Axial and oblique loads of 100 N at 45° were simulated in the prosthetic crown. The bone results showed that the peak stresses decreased by 12% in zirconia implants with 2 parts for axial load and 30% for the oblique load. In single-body implants, the peak stresses decreased 12% in the axial load and 34% in the oblique load when a zirconia implant was used compared with a titanium implant. Although the stress values in megapascals are similar, it can be concluded that the zirconia implants decrease the stress peaks at the peri-implant bone area around the implant platform when compared with titanium implants.

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.

The use of the digital smile design concept as an auxiliary tool in periodontal plastic surgery.

Periodontal surgery associated with prior waxing, mock-up, and the use of digital tools to design the smile is the current trend of reverse planning in periodontal plastic surgery. The objective of this study is to report a surgical resolution of the gummy smile using a prior esthetic design with the use of digital tools. A digital smile design and mock-up were used for performing gingival recontouring surgery. The relationship between the facial and dental measures and the incisal plane with the horizontal facial plane of reference were evaluated. The relative dental height x width was measured, and the dental contour drawing was inserted. Complementary lines are drawn such as the gingival zenith, joining lines of the gingival and incisal battlements. The periodontal esthetic was improved according to the established design digital smile pattern. These results demonstrate the importance of surgical techniques and are well accepted by patients and are easy to perform for the professional. When properly planned, they provide the desired expectations. Periodontal Surgical procedures associated with the design digital smile facilitate the communication between the patient and the professional. It is, therefore, essential to demonstrate the reverse planning of the smile and periodontal parameters with approval by the patient to solve the esthetic problem.

Modified Double-Papillae Flap Technique With Subepithelial Connective Tissue Graft for Root Coverage in the Esthetic Zone: Case Report.

Gingival recession can compromise the esthetic appearance, leading to functional problems, hypersensitivity, and root caries. Several techniques have been implicated for root coverage, which includes pedicle grafts, free gingival grafts, connective tissue grafts, and guided-tissue regeneration. The double-papillae flap associated with subepithelial connective tissue is a predictable technique to cover isolated areas with insufficient attached gingiva apical to a recession. This case report demonstrates a surgical alternative to the technique using a sling periosteal suture to stabilize the connective tissue and pedicle flap during the initial phase of healing, increasing the potential of this periodontal procedure for gingival recession coverage.