Comparison of digitally assessed quality of posterior crown preparations performed with and without previous practice on patient-specific three-dimensional-printed teeth models.

INTRODUCTION: Three-dimensional (3D)-printing technology can provide customizable simulations, but its effects on patient care quality have not been well studied. This study aimed to assess the impact of practicing with patient-specific 3D-printed teeth models on the quality of patients' dental preparations performed by students transitioning to clinical training. Accordingly, the quality of posterior crown preparations was evaluated by objectively analyzing digital scans and grades in two groups: the study group, which practiced beforehand with patient-specific 3D-printed teeth models, and the control group, which did not practice with these models. METHODS: All 78 fourth-year dental students who had just finished their fixed prosthodontics course at the simulation laboratory with training on phantom heads and without previous clinical experience in crown preparations were invited to participate in the study. Sixty-eight agreed to take part and were randomly divided into a study group that practiced crown preparations on 3D-printed models of their own patient's teeth and a control group that did not practice with 3D-printed models and started their clinical work straightforwardly after simulation training. Students completed validated perception questionnaires on self-confidence and clinical skills before and after the protocol, which were compared using a chi-squared test. Crown preparations performed on 3D-printed models and then on patients were digitally scanned and objectively graded by prepCheck software for critical parameters, such as undercuts, taper, and occlusion reduction. Non-parametric tests were used to compare preparations on 3D-printed models and on patients performed by the study group and those on patients made by the control group. RESULTS: Initially, both groups reported similar perceptions of self-confidence and clinical skills levels. The study group significantly improved both aspects after the protocol. Analysis of the scanned preparations demonstrated that the study group removed less tooth structure from actual patients than from the initial 3D-printed models. In contrast, the control group showed excess occlusal clearance in their patients compared to the study group. CONCLUSIONS: Practicing patient-specific 3D-printed teeth before performing procedures clinically appears to enhance preparation quality and minimize unnecessary tooth reduction in early clinical experiences.

Survival rate of sealed, refurbished and repaired defective restorations: 4-year follow-up.

The most common treatment in general dental practice is the replacement of restorations affected by secondary caries or marginal deficiencies. Alternative treatments to replacement of defective restorations, such as marginal sealing, refurbishment and repair, have demonstrated improvement of their clinical properties with minimal intervention. The aim of this clinical study was to estimate the median survival time (MST) of marginal sealing, repair and refurbishment of amalgam and resin-based composite restorations with localized defects as a treatment to increase the restoration longevity. A cohort of 66 patients, with 271 class I and II restorations clinically diagnosed with localized defects was longitudinally assessed. Each restoration was assigned to one of the following 5 groups: Marginal Sealing (n=48), Refurbishment (n=73), Repair (n=27), Replacement (n=42), and Untreated (n=81). Two calibrated examiners assessed the restorations at baseline and annually during 4 years, using the modified Ryge criteria: marginal adaptation, anatomic form, roughness, secondary caries and luster. Fifty-two patients with 208 restorations were assessed after 4 years; the distribution of restorations in the groups was as follows: Marginal Sealing (n=36), Refurbishment (n=63), Repair (n=21), Replacement (n=28) and Untreated (n=60). Kaplan Meier test indicated that the Sealed margins group showed the lowest MST while the Repair group showed the highest MST for restorations examined after 4 years of follow up. Defective amalgam and resin-based composite restorations treated by sealing of marginal gaps, refurbishment of anatomic form, luster or roughness, and repair of secondary caries lesions, had their longevity increased.

Survival rate of sealed, refurbished and repaired defective restorations: 4-year follow-up

The most common treatment in general dental practice is the replacement of restorations affected by secondary caries or marginal deficiencies. Alternative treatments to replacement of defective restorations, such as marginal sealing, refurbishment and repair, have demonstrated improvement of their clinical properties with minimal intervention. The aim of this clinical study was to estimate the median survival time (MST) of marginal sealing, repair and refurbishment of amalgam and resin-based composite restorations with localized defects as a treatment to increase the restoration longevity. A cohort of 66 patients, with 271 class I and II restorations clinically diagnosed with localized defects was longitudinally assessed. Each restoration was assigned to one of the following 5 groups: Marginal Sealing (n=48), Refurbishment (n=73), Repair (n=27), Replacement (n=42), and Untreated (n=81). Two calibrated examiners assessed the restorations at baseline and annually during 4 years, using the modified Ryge criteria: marginal adaptation, anatomic form, roughness, secondary caries and luster. Fifty-two patients with 208 restorations were assessed after 4 years; the distribution of restorations in the groups was as follows: Marginal Sealing (n=36), Refurbishment (n=63), Repair (n=21), Replacement (n=28) and Untreated (n=60). Kaplan Meier test indicated that the Sealed margins group showed the lowest MST while the Repair group showed the highest MST for restorations examined after 4 years of follow up. Defective amalgam and resin-based composite restorations treated by sealing of marginal gaps, refurbishment of anatomic form, luster or roughness, and repair of secondary caries lesions, had their longevity increased.

Na clínica odontológica geral, o tratamento mais comum é a substituição de restaurações com cárie secundária ou defeitos marginais. Tratamentos alternativos às substituições de restaurações defeituosas, como selamento marginal, recuperação, e reparo, têm proporcionado melhorias das propriedades clínicas, com um mínimo de intervenção. O objetivo deste estudo foi avaliar o tempo médio de sobrevida (median survival time - MST, na sigla em inglês) de selamento marginal, recuperação e reparo de restaurações de amálgama e compósitos resinosos com defeitos localizados, como tratamento para aumentar a longevidade das restaurações. Este foi um estudo longitudinal envolvendo 66 pacientes com 271 restaurações classe I e II, clinicamente diagnosticadas e com defeitos localizados. Cada restauração foi incluída num dos seguintes grupos: Selamento Marginal (n=48), Recuperação (n=73), Reparo (n=27), Substituição (n=42) e Sem tratamento (n=81). Dois examinadores calibrados avaliaram as restaurações no início e anualmente durante 4 anos, usando os critérios de Ryge modificados: adaptação marginal, forma anatômica, rugosidade, cárie secundária e brilho. Cinqüenta e dois pacientes com 208 restaurações foram avaliados após 4 anos; a distribuição das restaurações nos grupos foi a seguinte: Selamento Marginal (n=36), Recuperação (n=63), Reparo (n=21), Substituição (n=28) e Sem tratamento (n=60). O teste de Kaplan Meier mostrou que o grupo do Selamento Marginal apresentou o menor valor de MST, enquanto que o grupo do Reparo mostrou o maior valor, para as restaurações avaliadas após o acompanhamento de 4 anos. As restaurações de amálgama e compósitos tratadas com selamento de fissuras marginais, recuperação da forma anatômica, brilho ou rugosidade e reparo de cárie secundária, tiveram aumento de longevidade.

Peripheral blood mononuclear cells acquire myofibroblast characteristics in granulation tissue.

BACKGROUND: Bone marrow-derived cell populations possess progenitor cell capacities. Emerging evidence also suggests significant plasticity of differentiated mononuclear cell lineages. We therefore assessed the distribution of transplanted peripheral blood mononuclear cells (PBMCs) in granulation tissue formation, and evaluated their possible transdifferentiation into myofibroblasts. METHODS: Silastic tubes were inserted into the peritoneal cavity of rats, followed by injection of PKH26-labelled PBMCs isolated from donor animals. At 3, 14 and 21 days, the distribution of PKH26(+) cells as well as their colocalization with myofibroblast/smooth muscle cell [alpha-smooth muscle (alpha-SM) actin] or macrophage markers (ED1/ED2) were determined. RESULTS: Round-shaped PKH26(+) cells accumulated around the implants at 3 days, while myofibroblasts were rare. Later, peritoneal granulation tissue constituted an inner, multilayered capsule primarily comprising alpha-SM actin(+) cells that was surrounded by more loosely organized inflammatory connective tissue. PKH26-labelled, spindle-shaped cells were abundantly found in tissue capsules. As a key finding, granulation tissue at 14 and 21 days contained cells with both PKH26 and alpha-SM actin labelling. Accordingly, a subpopulation of cells staining positive for macrophage markers showed a spindle-shaped morphology and alpha-SM actin expression. CONCLUSIONS: Transplanted PBMCs contribute to granulation tissue, and acquire myofibroblast characteristics during de novo tissue formation. Mononuclear cells may transdifferentiate into myofibroblast-like cells within an inflammatory environment.