Clinical efficacy of xenogeneic collagen matrix in augmenting keratinized mucosa round dental implants: a systematic review and meta-analysis.

OBJECTIVES: This study aimed to evaluate the clinical effects of xenogeneic collagen matrix (XCM) in augmenting keratinized mucosa width (KMW) around dental implants. MATERIALS AND METHODS: Articles that were published before or during April 2020 were electronically searched in four databases without any date or language restrictions and manually searched in regular journals and grey literature. The eligibility criteria comprised randomized controlled trials (RCTs) or prospective studies that analysed the clinical efficacy of XCM for augmenting KMW around dental implants. This systematic review (SR) was registered in PROSPERO under number CRD42018115399. RESULTS: Eleven studies published between 2009 and 2019 were included in this SR. There was no significant difference in KMW increase (p = 0.14), probing depth (PD) decrease (p = 0.17) or participants' aesthetic satisfaction (PAS) (p = 0.32) when XCM was compared to connective tissue graft (CTG). However, the increase in gingival thickness (GT) was significantly higher (p = 0.001) with the use of CTG. CONCLUSIONS: The use of XCM improved KMW and PD with rates comparable to those for CTG. XCM showed lower results for GT when compared to CTG. XCM presented similar results in terms of PAS when compared to CTG. CLINICAL RELEVANCE: The presence of a KMW around dental implants is associated with better peri-implant tissue health.

Marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS).

UNLABELLED: Marginal integrity is one of the most crucial aspects involved in the clinical longevity of resin composite restorations. OBJECTIVE: To analyze the marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS). MATERIAL AND METHODS: A base composite (B) was produced with an organic matrix with UDMA/TEGDMA and 70 wt.% of barium borosilicate glass particles. To produce the model composite, 25 wt.% of UDMA were replaced by POSS (P25). The composites P90 and TPH3 (TP3) were used as positive and negative controls, respectively. Marginal integrity (%MI) was analyzed in bonded class I cavities. The volumetric polymerization shrinkage (%VS) and the polymerization shrinkage stress (Pss - MPa) were also evaluated. RESULTS: The values for %MI were as follows: P90 (100%) = TP3 (98.3%) = B (96.9%) > P25 (93.2%), (p<0.05). The %VS ranged from 1.4% (P90) to 4.9% (P25), while Pss ranged from 2.3 MPa (P90) to 3.9 MPa (B). For both properties, the composite P25 presented the worst results (4.9% and 3.6 MPa). Linear regression analysis showed a strong positive correlation between %VS and Pss (r=0.97), whereas the correlation between Pss and %MI was found to be moderate (r=0.76). CONCLUSIONS: The addition of 25 wt.% of POSS in methacrylate organic matrix did not improve the marginal integrity of class I restorations. Filtek P90 showed lower polymerization shrinkage and shrinkage stress when compared to the experimental and commercial methacrylate composite.

Marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS)

Marginal integrity is one of the most crucial aspects involved in the clinical longevity of resin composite restorations.Objective To analyze the marginal integrity of restorations produced with a model composite based on polyhedral oligomeric silsesquioxane (POSS).Material and Methods A base composite (B) was produced with an organic matrix with UDMA/TEGDMA and 70 wt.% of barium borosilicate glass particles. To produce the model composite, 25 wt.% of UDMA were replaced by POSS (P25). The composites P90 and TPH3 (TP3) were used as positive and negative controls, respectively. Marginal integrity (%MI) was analyzed in bonded class I cavities. The volumetric polymerization shrinkage (%VS) and the polymerization shrinkage stress (Pss - MPa) were also evaluated.Results The values for %MI were as follows: P90 (100%) = TP3 (98.3%) = B (96.9%) > P25 (93.2%), (p<0.05). The %VS ranged from 1.4% (P90) to 4.9% (P25), while Pss ranged from 2.3 MPa (P90) to 3.9 MPa (B). For both properties, the composite P25 presented the worst results (4.9% and 3.6 MPa). Linear regression analysis showed a strong positive correlation between %VS and Pss (r=0.97), whereas the correlation between Pss and %MI was found to be moderate (r=0.76).Conclusions The addition of 25 wt.% of POSS in methacrylate organic matrix did not improve the marginal integrity of class I restorations. Filtek P90 showed lower polymerization shrinkage and shrinkage stress when compared to the experimental and commercial methacrylate composite.

A influência da pré-carga em parafusos protéticos com e sem DLC sob forças laterais / The influence of preloading on DLC and non-DLC prosthetic screws under lateral forces

Objetivo: avaliar a influência de forças laterais aplicadas sobre os pilares em relação aos dois tipos de parafusos utilizados (com e sem DLC), de um mesmo sistema de implante. Material e métodos: neste trabalho, 20 parafusos protéticos de titânio sem tratamento de superfície (Neodent, Curitiba-PR, Brasil) e 20 parafusos com tratamento de superfície à base de carbono (Neotorque/Neodent, Curitiba-PR, Brasil), submetidos ou não a uma pré-carga inicial, foram comparados quanto à sua resistência in vitro através da aplicação de força perpendicular ao pilar do tipo reto (máquina universal de ensaios mecânicos – modelo EMIC DL100), fixado ao análogo do implante hexágono externo. Resultados: os resultados foram submetidos a testes estatísticos (Kruskal-Wallis), demonstrando não haver evidências para rejeitar a hipótese de igualdade entre os valores médios da força (N) entre os grupos (p-valor=0,2879). Uma grande variabilidade (desvio-padrão) entre as amostras pôde ser observada nos grupos dos parafusos Neotorque, onde o maior desvio-padrão foi encontrado no grupo dos parafusos Neotorque com pré-carga (99,89 N). O valor máximo de resistência foi verificado no grupo dos parafusos Neotorque com pré-carga (561,74 N). Conclusão: não há grande relevância clínica para a escolha de determinado parafuso, diante das forças perpendiculares aos componentes protéticos.

Objective: to evaluate the influence of preload and lateral forces on two abutment screw types. Material and methods: Twenty titanium prosthetic screws (non-DLC, Neodent) and (DLC-coated, Neotorque) were fastened to a external hexagon implant analog and submitted or not to an initial preload. After, their in vitro resistance were verified under perpendicular loading (universal testing machine - EMIC DL100). Results: the Kruskal-Wallis test demonstrated no differences between DLC and non-DLC groups (p=0.2879). A considerable standard deviation value was observed at the Neotorque screws, mainly for groups with applied preload (561.74N). Conclusion: within the limits of this study, the choice of prosthetic screw has no clinical implications based on perpendicular forces.