Color stability of a resin nanoceramic after surface treatments, adhesive cementation, and thermal aging.

STATEMENT OF PROBLEM: Whether color changes in resin nanoceramic (RNC) restorations can occur because of material and adhesive interface degradation is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the color of RNCs submitted to surface treatments, cementation, and aging. MATERIAL AND METHODS: RNC specimens (N=120) were produced with a thickness of 0.5 mm. The No Treatment-High/Low Translucency (NT-HT/LT) groups did not receive treatments; the Airborne-particle Abrasion-High/Low Translucency (AA-HT/LT) groups were airborne-particle abraded, and the Airborne-particle Abrasion Silane-High/Low Translucency (AASIL-HT/LT) groups received airborne-particle abrasion and a silane agent. Single specimens (n=60) were measured on a spectrophotometer before and after aging (50 000 cycles). The other half was mounted on composite resin bases and measured. The cleaned specimens were cemented (C) on the bases and measured (T0 and T1). ΔE00, ΔL', ΔC', and ΔH' were obtained by using the CIEDE2000 formula and analyzed by using ANOVA and repeated-measures ANOVA. Multiple comparisons were made by using the Tukey HSD test (α=.05). RESULTS: For single specimens, the greatest ΔE00 values were observed in the AA-T1-LT resin (5.87). For mounted and cemented conditions, the greatest ΔE00 values were found in the AA-C-T1-LT resin (1.74), and the ΔE00 ranged from 0.75 (NT-OL) to 1.44 (AASIL-C-T1) for the HT resin (P<.001). The mounted and cemented specimens tended toward red and yellow, whereas lighter specimens were observed after cementation. CONCLUSIONS: Aging affected the color of the RNCs evaluated. The single specimens showed greater color differences than the cemented specimens, reinforcing the importance of the adhesive cement in the optical behavior of thin restorations.

Residual monomer elution from different conventional and CAD/CAM dental polymers during artificial aging.

OBJECTIVES: Analyze and quantify the residual monomer elution of nine conventional and CAD/CAM (computer-aided design/computer-aided manufacturing) dental polymers during artificial aging. MATERIALS AND METHODS: A total of 360 square-shaped specimens (14 × 12 × 2 ± 0.05 mm) were fabricated from eight CAD/CAM polymer blanks (n = 40): Avadent Base material, Avadent Teeth material, PMMA Multi blank, PMMA Mono blank, Temp Premium, Telio CAD, Ceramill Temp, Shofu Block HC, and conventional polymer PalaXpress. Specimens were aged in distilled water for 60 days at 37 °C and the evaluation of the residual monomer elution was made through UV spectrophotometry. Statistical analysis was carried out in the SPSS software. One-way ANOVA and Scheffé post hoc test were applied (α < 0.05). RESULTS: Aging time significantly changed the elution in all groups, except for PalaXpress. Statistically significant differences of elution were found between the materials. Shofu Block HC presented the highest, whereas PMMA Multi blank A3 and Mono blank A1 presented the lowest elution after the 60th day of aging. CONCLUSIONS: CAD/CAM dental polymers as well as the conventional polymer PalaXpress eluted residual monomer within aging time. The differences in elution were material-dependent; still, the maximum elution found is below the specified threshold of ISO standard 20795-1. CLINICAL RELEVANCE: With the evolution of CAD/CAM technology, material's manufacturers have invested in the development of polymeric materials with higher resistance and stability to produce indirect restorations using CAD/CAM. It is expected that these materials present lower elution of residual monomer than conventional polymers.

Esthetic and functional rehabilitation of bilateral congenital absence of maxillary lateral incisors: Minimally invasive surgical and prosthetic approach.

OBJECTIVE: Congenital absence of maxillary lateral incisors is a frequent clinical challenge which must be solved by a multidisciplinary approach in order to obtain an esthetic and functional restorative treatment. Noninvasive treatments, that are in accordance with the patients' expectations, should be the first therapeutic alternative. If the deciduous tooth is present, minimally invasive dental extraction followed by immediate dental implant placement and provisional restoration is indicated. In this restorative treatment, an adequate emergency profile can be achieved by peri-implant soft-tissue-conditioning techniques. Moreover, the association of restorative materials, such as composite resins and dental ceramics, provides more predictable esthetic results. CLINICAL CONSIDERATIONS: The present case report presents a rehabilitation of bilateral congenital absence of maxillary lateral incisors through a multidisciplinary approach. Dental implants, long-term provisional restoration, tooth bleaching, minimally veneered high-translucent monolithic zirconia crowns, feldspathic veneers, and composite restorations were used by the dental team to achieve the expected functional and esthetic outcomes. CONCLUSIONS: Different treatment modalities are available for the rehabilitation of congenital absence of teeth. However, it is important that a dental team consider performing minimally invasive treatments, as many of these treatments are done on young patients. CLINICAL SIGNIFICANCE: Patient-centered treatments involving minimally invasive approaches in a multidisciplinary environment would be appropriate in order to achieve predictable results.

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.