Multidisciplinary action in a patient with cleft lip and palate: esthetic-functional dentofacial treatment for more than two decades / Atuação multidisciplinar em paciente com fissura lábio palatina: tratamento estético-funcional dento-facial de mais de duas décadas

Cleft lip and palate is a very common congenital defect in which embryonic facial processes do not achieve the ideal facial formation during their development which can cause malformation. Multiple dentistry specializations, especially oral and maxillofacial, orthodontics, oral rehabilitation and dental aesthetics are required in order to correct lip and oral cavity malformations by this congenital defect with the objective of functional and aesthetics improvement. The clinical case reported show the multidisciplinary approach in a patient with cleft lip and palate implementing an aesthetic and functional dentofacial rehabilitation. The case involves a 27-year-old female patient LCLG, Caucasian, with the presence of unilateral congenital cleft lip and palate on the left side, who started rehabilitative and reparative treatment at 3 months of age. She then started pediatric orthodontic treatment for angle class 3 crossbite correction at 7 years of age. After complete replacement of deciduous to permanent dentition at the age of 11, the patient started orthodontic treatment with a fixed appliance for several years and restorative treatment with composite resin reanatomize the anterior teeth due to agenesis of elements 22 and 25. After a few years when the resin restorations were no longer biologically favorable, an aesthetic rehabilitation treatment with ceramic laminates was planned through smile digital planning soon after completing the orthodontic treatment. This case report demonstrates that high aesthetic, functional and psychological expectations of a patient with congenital defect compromise throughout her life were met through a multidisciplinary dental treatment based on correct diagnosis and digital planning (AU)

A fissura labiopalatal é um defeito congênito muito comum, no qual os processos faciais embrionários não atingem a formação facial ideal durante o seu desenvolvimento, podendo causar malformações. Múltiplas especializações da odontologia, principalmente buco-maxilo-facial, ortodontia, reabilitação oral e estética dental são necessárias para corrigir as malformações labiais e da cavidade oral por esse defeito congênito com o objetivo de melhoria funcional e estética. O caso clínico relatado mostra a abordagem multidisciplinar em um paciente com fissura labiopalatal implementando uma reabilitação dentofacial estética e funcional. O caso envolve uma paciente do sexo feminino, 27 anos, LCLG, branca, com presença de fissura labiopalatal congênita unilateral à esquerda, que iniciou tratamento reabilitador e reparador aos 3 meses de idade. Após a substituição completa da dentição decídua pela permanente aos 11 anos de idade, a paciente iniciou tratamento ortodôntico com aparelho fixo por vários anos, e tratamento restaurador com resina composta para reanatomizar os dentes anteriores devido à agenesia dos elementos 22 e 25. Após alguns anos em que as restaurações em resina não eram mais favoráveis biologicamente, foi planejado um tratamento reabilitador estético com laminados cerâmicos através do planejamento digital do sorriso logo após a finalização do tratamento ortodôntico. Este relato de caso demonstra que as altas expectativas estéticas, funcionais e psicológicas de uma paciente com comprometimento de defeito congênito ao longo de sua vida foram atendidas por meio de um tratamento odontológico multidisciplinar baseado em diagnóstico correto e planejamento digital (AU)

Effect of Resin Cement at Different Thicknesses on the Fatigue Shear Bond Strength to Leucite Ceramic.

OBJECTIVES: This in vitro study was performed to evaluate fatigue survival by shear test in the union of leucite-reinforced feldspathic ceramic using different cement thicknesses. MATERIALS AND METHODS: Leucite-reinforced glass ceramics blocks were sectioned in 2-mm thick slices where resin cylinders were cemented. The samples were distributed in two experimental groups (n = 20) according to the cement thickness (60 and 300 µm). The specimens of each group were submitted to the stepwise fatigue test in the mechanical cycling machine under shear stress state, with a frequency of 2 Hz, a step-size of 0.16 bar, starting with a load of 31 N (1.0 bar) and a lifetime of 20,000 cycles at each load step. RESULTS: The samples were analyzed in a stereomicroscope and scanning electron microscopy to determine the failure type. There is no significant difference between the mean values of shear bond strength according to both groups. Log-rank (p = 0.925) and Wilcoxon (p = 0.520) tests revealed a similar survival probability in both cement layer thicknesses according to the confidence interval (95%). The fracture analysis showed that the mixed failure was the most common failure type in the 300-µm thickness group (80%), while adhesive failure was predominant in the 60-µm thickness group (67%). The different cement thicknesses did not influence the leucite ceramic bonding in fatigue shear testing; however, the thicker cement layer increased the predominance of the ceramic material failure. CONCLUSION: The resin cement thicknesses bonded to leucite ceramic did not influence the long-term interfacial shear bond strength, although thicker cement layer increased the ceramic material cohesive failure. Regardless the cement layer thickness, the shear bond strength lifetime decreases under fatigue.

Effect of Biologically Oriented Preparation Technique on the Stress Concentration of Endodontically Treated Upper Central Incisor Restored with Zirconia Crown: 3D-FEA.

The aim of this study was to evaluate the effect of biologically oriented preparation technique on the stress concentration of endodontically treated upper central incisors restored with zirconia crown (yttria-stabilized zirconia polycrystalline ceramic) through finite element analysis (FEA). Four models of maxillary central incisors containing enamel, dentin, periodontal ligament, cortical and medullary bone were created in CAD. Each model received a polymeric core-build up with nanofilled dental resin composite. The evaluated models were SM-preparation in shoulder 90°; CM-chamfer preparation; BOPT-biologically oriented preparation technique and BOPTB-BOPT preparation 1 mm below the cement-enamel junction. All models received zirconia crowns (5Y-TZP), fiberglass post and 1 mm ferrule. The models were imported into the analysis software with parameters for mechanical structural testing using the maximum principal stress and the tensile strength as the analysis criteria. Then, load of 150 N was applied at the cingulum with 45° slope to the long axis of the tooth, with the fixed base for each model. The type of marginal preparation affected the stresses concentration in endodontically treated teeth and in the zirconia crown margin. Considering the stress magnitude only, BOPT is a viable option for anterior monolithic zirconia crowns; however, with the highest stress magnitude at the restoration margin.

Mechanical behavior and microstructural characterization of different zirconia polycrystals in different thicknesses.

PURPOSE: To characterize the microstructure of three yttria partially stabilized zirconia ceramics and to compare their hardness, indentation fracture resistance (IFR), biaxial flexural strength (BFS), and fatigue flexural strength. MATERIALS AND METHODS: Disc-shaped specimens were obtained from 3Y-TZP (Vita YZ HT), 4Y-PSZ (Vita YZ ST) and 5Y-PSZ (Vita YZ XT), following the ISO 6872/2015 guidelines for BFS testing (final dimensions of 12 mm in diameter, 0.7 and 1.2 ± 0.1 mm in thicknesses). Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were performed, and mechanical properties were assessed by Vickers hardness, IFR, quasi-static BFS and fatigue tests. RESULTS: All ceramics showed similar chemical compositions, but mainly differed in the amount of yttria, which was higher as the amount of cubic phase in the diffractogram (5Y-PSZ > 4Y-PSZ > 3Y-TZP). The 4Y- and 5Y-PSZ specimens showed surface defects under SEM, while 3Y-TZP exhibited greater grain uniformity on the surface. 5Y-PSZ and 3Y-TZP presented the highest hardness values, while 3Y-TZP was higher than 4Y- and 5Y-PSZ with regard to the IFR. The 5Y-PSZ specimen (0.7 and 1.2 mm) showed the worst mechanical performance (fatigue BFS and cycles until failure), while 3Y-TZP and 4Y-PSZ presented statistically similar values, higher than 5Y-PSZ for both thicknesses (0.7 and 1.2 mm). Moreover, 3Y-TZP showed the highest (1.2 mm group) and the lowest (0.7 mm group) degradation percentage, and 5Y-PSZ had higher strength degradation than 4Y-PSZ group. CONCLUSION: Despite the microstructural differences, 4Y-PSZ and 3Y-TZP had similar fatigue behavior regardless of thickness. 5Y-PSZ had the lowest mechanical performance.

Caracterização microestrutural e resistência à fadiga de zircônias de alta, super e extra translucidez / Microstructural characterization and fatigue strength of high, super and extra translucent zirconia ceramics

O objetivo deste estudo foi caracterizar a microestrutura de cerâmicas de zircônia parcialmente estabilizada com ítria com diferentes níveis de translucidez e avaliar o efeito na dureza, tenacidade à fratura e resistência à flexão biaxial (ensaio com carga monotônica e resistência à fadiga). Amostras em forma de disco foram obtidas de cerâmica de zircônia de alta translucidez (Vita YZ HT), super translucidez (Vita YZ ST) e extra translucidez (Vita YZ XT), seguindo as diretrizes da ISO 6872/2015 para testes de resistência à flexão biaxial, e também na menor espessura de utilização indicada pelo fabricante (dimensões finais de 12 mm de diâmetro, 0,7 e 1,2 ± 0,1 mm de espessura). Para a caracterização, foram realizadas análises de difração de raios-X (DRX), microscopia eletrônica de varredura (MEV) e espectroscopia de dispersão de energia (EDS), para análise das propriedades mecânicas, dureza Vickers, tenacidade à fratura e resistência à flexão biaxial (ensaio com carga monotônica) e ensaio de resistência à fadiga em flexão biaxial (ensaio acelerado step-stress). A zircônia ST e XT apresentaram defeitos superficiais na análise de MEV, enquanto a zircônia HT apresentou maior uniformidade dos grãos na superfície. Todas as cerâmicas apresentaram composições químicas semelhantes, diferindo principalmente na quantidade de ítria, que foi maior com o aumento da translucidez do material; nos resultados de DRX, a quantidade de fase cúbica também foi maior com o aumento da translucidez (XT> ST> HT). XT e HT apresentaram os maiores valores de dureza e quanto à tenacidade à fratura, HT difere de ST e XT, que foram semelhantes. Em relação à resistência à fadiga e probabilidade de sobrevivência, XT (0,7 mm e 1,2 mm) apresentou o pior desempenho mecânico (resistência à flexão biaxial à fadiga e ciclos até a falha), enquanto HT e ST apresentaram valores estatisticamente semelhantes e superiores à XT, mesmo em espessuras finas (0,7 mm) e espessura convencional (1,2 mm). A zircônia super translúcida (ST) apresenta comportamento de fadiga semelhante à zircônia altamente translúcida HT, que já possui um excelente reconhecimento na literatura. Cerâmicas de extra translucidez (XT) ainda precisam evoluir no processamento. Mudanças na microestrutura das cerâmicas de zircônia translúcida e na quantidade de ítria disminuiram as propriedades mecânicas(AU)

The aim of this study was to characterize the microstructure of Yttria partially stabilized zirconia ceramics with different levels of translucency and to evaluate the effect on the hardness, fracture toughness and biaxial flexural strength (monotonic and fatigue). Disc-shaped specimens were obtained from high translucency (Vita YZ HT), super translucency (Vita YZ ST) and extra translucency zirconia ceramics (Vita YZ XT), following ISO 6872/2015 guidelines for biaxial flexural strength testing (final dimensions of 12 mm in diameter, 0.7 and 1.2 ± 0.1 mm in thickness). For characterization, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and energy dispersion spectroscopy (EDS) analyzes were performed and for mechanical properties, Vickers hardness, fracture toughness and biaxial flexural strength (monotonic and fatigue). The ST and XT zirconia showed surface defects under SEM analysis, while HT zirconia exhibited greater grain uniformity on the surface. All ceramics showed similar chemical compositions, differing mainly in the amount of yttria, which was higher as the translucency of the material increased; and in XRD the amount of cubic phase was also greater with the increased translucency (XT > ST > HT). XT and HT present the highest hardness values and about the fracture toughness, HT differs from ST and XT, which were similar. Regarding the fatigue strength and survival probability, XT (0.7 mm and 1.2 mm) showed the worst mechanical performance (fatigue biaxial flexural strength and cycles until failure), while HT and ST presented statistically similar values and higher than XT, even between thin (0.7 mm) and conventional thickness (1.2 mm). Super translucent zirconia (ST) has similar fatigue behavior than high-translucent zirconia HT, which already has an excellent recognition in the literature. Extra (XT) translucency ceramics still need to evolve in processing. Changes in the microstructure of translucent zirconia ceramics and the amount of yttria have reduced the mechanical properties(AU)