Effect of screw-access hole and mechanical cycling on fracture load of 3-unit implant-supported fixed dental prostheses.

STATEMENT OF PROBLEM: The effect of screw-access holes and mechanical cycling on fracture resistance of 3-unit screw-retained zirconia-based implant-supported fixed dental prostheses (ISFDPs) is unknown. PURPOSE: The purpose of this in vitro study was to evaluate the effect of screw-access holes on the maximum fracture load (Lf) of 3-unit ISFDPs fabricated with the same abutment design for screw (s)-retained and cement (c)-retained with either a metal- or zirconia-based framework, testing the hypotheses that ISFDPs with screw-access holes have the lowest Lf and that mechanical cycling decreases the Lf of screw-retained ISFDPs. MATERIAL AND METHODS: Models with fiberglass bases with 2 implants were fabricated. Special abutments were designed to allow for both s- and c-retained ISFDPs. The study considered the type of framework (s-retained metal-based and s-retained zirconia-based), fixation (s and c), and aging (a) with mechanical cycling, resulting in the following experimental groups (n=12): c-retained metal-based ISFDP; s-retained metal-based ISFDP (Ms); s-retained zirconia-based ISFDP aged by mechanical cycling (Zsa); and s-retained metal-based ISFDP aged by mechanical cycling (Msa). All ISFDPs were porcelain veneered and subjected to compressive load to failure. Fracture load data were statistically analyzed using 1-way ANOVA and Tukey range tests (α=.05). Fractography was used to evaluate the fracture surfaces. RESULTS: Cement-retained ISFDP (Zc and Mc) showed the greatest Lf values (P<.001). Zs prostheses showed higher Lf values than those for Ms. Aging significantly decreased the Lf of Zsa but had no effect on Msa. Chipping was the failure mode most frequently found. Only Zs and Zsa ISFDPs showed catastrophic failures. CONCLUSIONS: ISFDPs with screw-access holes showed lower Lf values, regardless of the framework type. Mechanical cycling affected the Lf of screw-retained zirconia-based ISFDPs.

Influences of Screw Access Hole and Mechanical Cycling on the Fracture Load of Implant-Supported Crowns.

PURPOSE: To assess the influence of a screw access hole (SAH) and mechanical cycling on the fracture load of implant-supported crowns (ISCs) manufactured with screw-retained (s) or cement-retained (c) abutments with either metal (M) or zirconia (Z) infrastructure. MATERIALS AND METHODS: Six groups of restorations were made based on type of infrastructure (M or Z), fixation (s or c), and whether they underwent aging (a) with mechanical cycling: Zc, Zs, Zsa, Mc, Ms, and Msa. All ISCs were porcelain veneered and tested for compression to failure in distilled water (37°C) using a universal testing machine. ISCs from groups Zsa and Msa were mechanically cycled (106 cycles; 2 Hz, 100 N) in distilled water before compressive testing. Fractographic principles were followed to assess the fracture surfaces. The fracture load data were statistically analyzed using one-way analysis of variance and Tukey test (α = .05). The relationships between experimental group and failure mode were analyzed using chi-square test (α = .05). RESULTS: Regardless of the infrastructure material, cement-retained ISCs (Zc and Mc) showed higher fracture load values than screw-retained ISCs (Zs, Zsa, Ms, and Msa) (P < .001), which were statistically similar to each other (P > .05). Aging had no effect on the fracture load of ISCs. There was a significant relationship between failure mode and experimental group (P < .001). Catastrophic fractures were found only in Zc and Zs. All metal-based ISCs failed from chipping reaching the metal infrastructure. CONCLUSION: Cement-retained ISCs showed higher fracture resistance than screw-retained prostheses. No catastrophic failures were found for metal-based ISCs. Aging did not affect the fracture load, but did affect the failure mode of ISCs.

Uso de fibrina rica em plaquetas (PRF) no tratamento de perfurações da membrana sinusal / Use of platelet-rich fibrin (PRF) to treat sinus membrane perforations

A reabilitação de áreas edântulas sempre foi um desafio para os profissionais, em especial a posterior de maxila, pela pneumatização dos seios maxilares. Uma das complicações durante os procedimentos de levantamento sinusal são as perfurações da membrana. A fibrina rica em plaquetas (PRF), um concentrado de fatores de crescimento obtido a partir da centrifugação do sangue do paciente, tem a propriedade de acelerar o processo cicatricial, reparar as perfurações na membrana schneideriana e funcionar como material de preenchimento. O objetivo do presente estudo foi revisar a literatura e relatar um caso de selamento de perfuração de membrana sinusal utilizando membrana de fibrina (PRF) associada … hidroxiapatita bovina

Rehabilitation of edentulous areas has always been a challenge for dentists, especially on the posterior maxilla due to the pneumatization of the maxillary sinus. One of the complications during sinus lifting procedures is perforation of the membrane. The platelet-rich fibrin (PRF) is a complex of growth factors obtained from centrifuging the patient’s blood. It has the ability to accelerate the healing process and repair damages in the Schneiderian membrane, therefore, functioning as a filling material. The aim of this study was to perform a literature review and report a clinical case of sealing membrane perforation using PRF associated with bovine hydroxyapatite

Tratamento da fratura de mandíbula atrófica associada reabilitação com implantes dentários – relato de caso / Treatment of atrophic mandible fracture combined to rehabilitation with dental implants – case report

O aumento da população idosa e o incremento da procura por tratamentos reabilitadores faz com que os profissionais dedicados a esta arte se depararem com a necessidade de reabilitação de mandíbulas atróficas e com o risco de sua fratura. A proposta deste trabalho foi apresentar o relato de um caso de tratamento de fratura de mandíbula atrófica. O caso foi tratado sob anestesia geral, com instalação de placa de fixação mandibular concomitante a instalação de 4 implantes cone morse para futura confecção de protocolo com desenho all on four. A técnica proporcionou adequada resolução para a fratura e proporcionou segurança para a futura reabilitação implantossuportada.

The increasing elderly population and increasing demand for rehabilitation treatments make professionals dedicated to this art faced with the need for rehabilitation of atrophic jaws and the risk of fracture. The purpose of this study was to present the case report of the treatment of atrophic mandible fractures. The patient was treated under general anesthesia, with installation of the mounting plate concomitant mandibular installing 4 morse taper implants for future preparation of protocol design on all four. The technique provided adequate resolution for fracture and provided security for the future rehabilitation implant.

Enxerto ósseo interposicional: uma alternativa viável para ganho ósseo vertical / Interpositional bone graft: a viable alternative to vertical bone augmentation

Nos planejamentos cirúrgicos para a Implantodontia, diferentes abordagens terapêuticas são possíveis para o tratamento dos defeitos ósseos, quando relacionados a defeitos em espessura. Porém, quando nos deparamos com defeitos verticais, a resolução torna-se mais complexa, uma vez que as técnicas aposicionais de enxertia são deficientes para o ganho ósseo vertical. Para tanto, a utilização da técnica de osteotomias segmentares seguida de enxertos de interposição fornece previsibilidade e segurança clínica. Com o objetivo de demonstrar essa técnica, apresenta-se um caso clínico de osteotomia segmentar seguida de enxerto interposicional com hidroxiapatita sintética reabsorvível na região anterior da maxila

In planning for surgical implants, some therapeutic approaches are possible for treating bone defects in thickness. However, when facing vertical defects, the resolution becomes more complex, since appositional grafting techniques are deficient for vertical bone gain. Therefore, using the technique of segmental osteotomies followed by interposition grafts provides predictable and clinically safe resolution. To demonstrate this technique, this paper presents a case of segmental osteotomy followed by interpositional graft with resorbable synthetic hydroxyapatite in the anterior maxilla

Estudo com desenho split-mouth com enxertos onlay de bloco alógeno e autógeno na maxila para futura colocação de implantes osseointegrados: resultados tomográficos e histológicos / A split-mouth study on allogeneic and autogenic onlay bone grafts in the maxillary arch for further dental implant placement: CBCT and histological results

O objetivo deste estudo foi verificar os resultados clínicos e histológicos de blocos onlay de osso autógeno e alógeno colocados na maxila. Um paciente feminino, 45 anos, recebeu, contralateralmente (split-mouth), blocos ósseos autógenos de ramo mandibular e blocos ósseos homógenos frescos congelados, de banco de ossos, e após oito e seis meses, respectivamente, para osso homógeno e autógeno, foi realizada a instalação de seis implantes. Clinicamente, observou-se maior reabsorção óssea nos blocos homógenos, com aspecto superficial mais irregular; já nos blocos autógenos, esta reabsorção foi menor, de aspecto superficial liso e contínuo. No momento da instalação dos implantes, observou-se menor densidade e/ou resistência ao corte nos blocos homógenos, porém, não alterando a estabilidade primária dos implantes; em ambos os blocos obteve-se 40 Ncm. Histologicamente, nos tempos utilizados de oito e seis meses, respectivamente para homógeno e autógeno, o resultado obtido na análise das lâminas foi muito semelhante, com presença de osteócitos aprisionados na matriz óssea, evidenciando tecido vital em ambas as amostras

The aim of this study was to evaluate the clinical and histological outcomes of onlay bone block and allografts placed in the maxillary arch. A female, 45 years-old patient received mandibular autogenous bone blocks and fresh-frozen allogenic grafts in a split-mouth design. After eight and six months for homogenous and autogenous bone, respectively, six dental implants were installed. Clinically, greater bone resorption was observed in the homogenous blocks, with more irregular surface aspect; in the autogenous blocks, the reabsorption degree was lower and smooth with a continuous surface. Upon implant placement, lower density and cutting resistance were seen in homogenous blocks, although not changing the final implant primary stability (40Ncm). Histologically, the obtained results were very similar, with the presence of osteocytes trapped into the bone matrix, showing vital tissue after eight and six months in both groups.

Dentinogênese imperfeita tipo II ou dentina opalescente hereditária: uma revisão de literatura e relato de caso clínico / Dentinogenesis imperfecta type II or hereditary opalescent dentin: literature review and case report

Os autores apresentam revisão bibliográfica e relato de um caso clínico de dentinogênese imperfeita tipo II numa paciente de vinte anos, leucoderma, com deficiência estética na dentição permanente. Clinicamente, os dentes apresentavam coloração castanho-amarelada, fraturas de esmalte, dentes com contorno anatômico anormais e dimensões coronárias menores no sentido inciso-gengival. Constatou-se a ocorrência de vários casos semelhantes na sua família, comprovando a hereditariedade dessa condição. Radiograficamente, observaram-se ausência de comprometimento ósseo e completa obliteração das câmaras pulpares, em virtude da produção desordenada de dentina displásica. O tratamento consiste na proteção das estruturas dentárias, como a utilização de coroas, sobredentaduras ou proteção interoclusal com placas de uso noturno