Marginal and internal fit of four-unit zirconia fixed dental prostheses based on digital and conventional impression techniques.

OBJECTIVES: The aim of this in vitro study was to evaluate the marginal and internal fit of CAD/CAM-generated four-unit zirconia fixed dental prostheses made with digital and conventional impressions. MATERIALS AND METHOD: A titanium master model was used. For group conventional impression (CI), 12 polyether impressions of the master model with Impregum(TM) were made. For group digital impression (DI), 12 digital impressions of the master model using Lava(TM) C.O.S. system were made. The replica technique was applied. The Mann-Whitney U statistical test was applied to detect statistical differences between the groups, in terms of marginal and internal fit. Face-by-face comparisons between groups were also carried out. RESULTS: Groups DI and CI presented mean marginal fit of 63.96 and 65.33 µm, respectively, and showed no statistically significant difference. Groups DI and CI presented significantly different internal fit with mean values of 58.46 and 65.94 µm, respectively. Group DI showed statistically significantly lower values for marginal and internal fit on premolar mesial face, and on molar distal and palatal faces. CONCLUSIONS: Frameworks fabricated from digital and conventional impressions showed clinically acceptable marginal fit. Frameworks fabricated from digital impression demonstrated better internal fit than ones fabricated from conventional impression. Reviewing each retainer face, digital impression showed better marginal and internal fit at the premolar mesial and molar distal faces. CLINICAL RELEVANCE: The results of this in vitro study show that digital impressions made with the Lava(TM) C.O.S. system and its digital workflow are suitable for fabricating four-unit zirconia frameworks, with regard to marginal and internal fit requirements.

Treatment concept with CAD/CAM-fabricated high-density polymer temporary restorations.

Tooth wear in younger patients is perceived worldwide as an increasing problem. Its etiology is multifactorial (erosion, abrasion, attrition), and its treatment is challenging for the dental practitioner specifically when a great loss of the vertical dimension of occlusion has occurred. The aim of this article is to present a treatment approach for complex cases with high loss of tooth structure using computer-aided design/computer-aided manufacturing (CAD/CAM)-fabricated temporary high-density polymer restorations without any preparations. New manufacturing technologies and innovative materials such as high-density polymers offer good possibilities for restorations during the pretreatment period. This is especially important in circumstances requiring massive corrections of color, form, or position. Pretreatment periods are indispensable in refining important factors such as lip-position dynamics as well as the correct position of the smile line, which cannot be adequately assessed in the dental laboratory. In the presented case report, CAD/CAM-fabricated non-preparation restorations were adhesively placed on the worn dentition without any further loss of tooth structure. Such an approach provides the opportunity to "test-drive" the new restoration design in terms of function, phonetics, and esthetics, thus improving the predictability of the definitive restorations design. If any change in the design is required, it can be cost-effectively achieved through simple modification or replacement of the restorations.

Dental erosion: understanding this pervasive condition.

Dental erosion is a contemporary disease, mostly because of the change of the eating patterns that currently exist in society. It is a "silent" and multifactorial disease, and is highly influenced by habits and lifestyles. The prevalence of dental erosion has considerably increased, with this condition currently standing as a great challenge for the clinician, regarding the diagnosis, identification of the etiological factors, prevention, and execution of an adequate treatment. This article presents a dental erosion review and a case report of a restorative treatment of dental erosion lesions using a combination of bonded ceramic overlays to reestablish vertical dimension and composite resin to restore the worn palatal and incisal surfaces of the anterior upper teeth. Adequate function and esthetics can be achieved with this approach.

Cigarette smoke affects bonding to dentin.

This in vitro study evaluated the microtensile bond strength (muTBS) of composite resin bonded to dentin that had been contaminated by cigarette smoke. Ten extracted unerupted human third molars were used: Six molars were prepared for muTBS testing, while the other four molars were assigned to pre- and post-etching scanning electronic microscopy (SEM) analysis. The 20 specimens obtained from the 10 coronal portions were distributed into two experimental groups so that each tooth served as its own control. Group 1 underwent a daily toothbrushing simulation and exposure to a smoking simulation chamber, while Group 2 received only a daily simulated toothbrushing. Student's t-test demonstrated that Group 1 samples demonstrated significantly lower bond strength (49.58 MPa) than Group 2 samples (58.48 MPa). Pre and postetching SEM analysis revealed the presence of contaminants on the dentinal surfaces of the Group 1 specimens. It was concluded that contamination by cigarette smoke decreases the bond strength between dentin and composite resin.

Erosão dental: uma doença dos tempos atuais / Dental erosion: a contemporary disease

A erosão dental é uma doença dos tempos atuais. Na maioria dos casos, decorre da mudança dos padrões alimentares da sociedade. É uma doença “silenciosa”, multifatorial, altamente influenciada por hábitos pessoais e estilos de vida. A prevalência da erosão dental tem aumentado consideravelmente, e atualmente se configura como grande desafio para o cirurgião-dentista elaborar o diagnóstico, identificar fatores etiológicos, executar tratamento adequado dessa patogenia e preveni-la. Este artigo apresenta uma revisão dos fundamentos teóricos referentes à erosão dental, bem como dos principais aspectos e fatores que a modulam.