Luca Giachetti

Bio: Luca Giachetti is an academic researcher from University of Florence. The author has contributed to research in topics: Dentin & Bond strength. The author has an hindex of 13, co-authored 31 publications receiving 644 citations.

A review of polymerization shrinkage stress: current techniques for posterior direct resin restorations.

Abstract: In general excellent results cannot be guaranteed when using resin-based composites for posterior restorations. This is due to polymerization shrinkage which can still be regarded as the primary negative characteristic of composite resins. A review of available literature regarding the polymerization process, its flaws, and suggested strategies to avoid shrinkage stress was conducted. Several factors responsible for the polymerization process may negatively affect the integrity of the tooth-restoration complex. There is no straightforward way of handling adhesive restorative materials that can guarantee the reliability of a restoration. At present, the practitioner has to coexist with the problem of polymerization shrinkage and destructive shrinkage stress. However, evolving improvements associated with resin-based composite materials, dental adhesives, filling, and light curing techniques have improved the predictability of such restorations. This critical review paper is meant to be a useful contribution to the recognition and understanding of problems related to polymerization shrinkage and to provide clinicians with the opportunity to improve the quality of composite resin restorations.

A Randomized Clinical Trial Comparing At-Home and In-Office Tooth Whitening Techniques: A nine-month follow-up

Abstract: Background The aim of this split-mouth, randomized controlled trial was to compare the whitening results of at-home and in-office tooth bleaching techniques and the longevity of their effects at nine months after teeth had been bleached. Methods The authors conducted a study involving a 14-day bleaching period, during which the first maxillary premolars of 17 participants, who were 20 to 25 years of age, were bleached by means of either an at-home technique involving 10 percent carbamide peroxide or an in-office technique involving 38 percent hydrogen peroxide. The authors recorded color variables as proposed by the Commission Internationale de l'Eclairage—lightness ( L *), redness ( a* ) and yellowness ( b* )—by using a spectrophotometer at baseline and at one week, one month and nine months after bleaching. They also calculated a whiteness (W) index that was based on the distance of the color value in the color space from a nominal white point. Results At the nine-month recall visit, comparison between the at-home and the in-office techniques did not show significantly different values for L * ( P = .448), a* ( P = .350), b* ( P = .144) and W ( P = .151) color variables. None of the participants experienced any adverse events related to the bleaching during the treatment period. Conclusions The study results showed no clinically significant difference in bleaching efficacy. Both techniques produced satisfactory and long-lasting bleaching results. Clinical Implications In young adults, either the at-home or the in-office technique can be used effectively.

Adhesion to Zirconia: A Systematic Review of Current Conditioning Methods and Bonding Materials

Abstract: Background. Reliable bonding between resin composite cements and high strength ceramics is difficult to achieve because of their chemical inertness and lack of silica content that makes etching impossible. The purpose of this review is to classify and analyze the existing methods and materials suggested to improve the adhesion of zirconia to dental substrate by using composite resins, in order to explore current trends in surface conditioning methods with predictable results. Methods. The current literature, examining the bond strength of zirconia ceramics, and including in vitro studies, clinical studies, and a systematic review, was analyzed. The research in the literature was carried out using PubMed and Cochrane Library databases, only papers in English, published online from 2013 to 2018. The following keywords and their combinations were used: Zirconia, 3Y-TZP, Adhesion, Adhesive cementation, Bonding, Resin, Composite resin, Composite material, Dentin, Enamel. Results. Research, in PubMed and Cochrane Library databases, provided 390 titles with abstracts. From these, a total of 93 publications were chosen for analysis. After a full text evaluation, seven articles were discarded. Therefore, the final sample was 86, including in vitro, clinical studies, and one systematic review. Various adhesive techniques with different testing methods were examined. Conclusions. Airborne-particle abrasion and tribo-chemical silica coating are the pre-treatment methods with more evidence in the literature. Increased adhesion could be expected after physico-chemical conditioning of zirconia. Surface contamination has a negative effect on adhesion. There is no evidence to support a universal adhesion protocol.

Biomechanical considerations for the restoration of endodontically treated teeth: a systematic review of the literature, Part II (Evaluation of fatigue behavior, interfaces, and in vivo studies).

Abstract: OBJECTIVE: The restoration of endodontically treated teeth has long been guided by empirical rather than biomechanical concepts. Part I of this literature review presented up-to-date knowledge about changes in tissue structure and properties following endodontic therapy, as well as the behavior of restored teeth in monotonic mechanical tests or finite element analysis. The aim of the second part is to review current knowledge about the various interfaces of restored, nonvital teeth and their behavior in fatigue and clinical studies. REVIEW METHOD: The basic search process included a systematic review of articles contained in the PubMed/Medline database, dating between 1990 and 2005, using single or combined key words to obtain the most comprehensive list of references; a perusal of the references of the references completed the review. RELEVANT INFORMATION AND CONCLUSIONS: Nonvital teeth restored with composite resin or composite resin combined with fiber posts resisted fatigue tests and currently represent the best treatment option. In comparison to rigid metal and/or ceramic posts, when composite resin or composite resin/fiber posts fail, the occurrence of interfacial defects or severe tooth breakdown is less likely. Adhesion into the root, however, remains a challenge because of the unfavorable ovoid canal configuration, as well as critical dentin microstructure in the deepest parts of the canal. Thus, specific combinations of adhesives and cements are recommended. The clinical performance of post-and-core restorations proved satisfactory overall, in particular with a contemporary restorative approach using composite resin and fiber posts. However, the clinical literature does not clearly isolate or identify exact parameters critical to success. This, in turn, emphasizes the importance and relevance of in vitro studies to further improve the quality and long-term stability of prosthetic foundations.

Mucogingival conditions in the natural dentition: Narrative review, case definitions, and diagnostic considerations

Abstract: Background Mucogingival deformities, and gingival recession in particular, are a group of conditions that affect a large number of patients. Since life expectancy is rising and people are retaining more teeth both gingival recession and the related damages to the root surface are likely to become more frequent. It is therefore important to define anatomic/morphologic characteristics of mucogingival lesions and other predisposing conditions or treatments that are likely to be associated with occurrence of gingival recession. Objectives Mucogingival defects including gingival recession occur frequently in adults, have a tendency to increase with age, and occur in populations with both high and low standards of oral hygiene. The root surface exposure is frequently associated with impaired esthetics, dentinal hypersensitivity and carious and non-carious cervical lesions. The objectives of this review are as follows (1) to propose a clinically oriented classification of the main mucogingival conditions, recession in particular; (2) to define the impact of these conditions in the areas of esthetics, dentin hypersensitivity and root surface alterations at the cervical area; and (3) to discuss the impact of the clinical signs and symptoms associated with the development of gingival recessions on future periodontal health status. Results An extensive literature search revealed the following findings: 1) periodontal health can be maintained in most patients with optimal home care; 2) thin periodontal biotypes are at greater risk for developing gingival recession; 3) inadequate oral hygiene, orthodontic treatment, and cervical restorations might increase the risk for the development of gingival recession; 4) in the absence of pathosis, monitoring specific sites seems to be the proper approach; 5) surgical intervention, either to change the biotype and/or to cover roots, might be indicated when the risk for the development or progression of pathosis and associated root damages is increased and to satisfy the esthetic requirements of the patients. Conclusions The clinical impact and the prevalence of conditions like root surface lesions, hypersensitivity, and patient esthetic concern associated with gingival recessions indicate the need to modify the 1999 classification. The new classification includes additional information, such as recession severity, dimension of the gingiva (gingival biotype), presence/absence of caries and non-carious cervical lesions, esthetic concern of the patient, and presence/absence of dentin hypersensitivity.

The role of resin cement on bond strength of glass-fiber posts luted into root canals: a systematic review and meta-analysis of in vitro studies.

Abstract: Because there are several ways to cement glass-fiber posts (GFPs) into root canals, there is no consensus on the best strategy to achieve high bond strengths. A systematic review was conducted to determine if there is difference in bond strength to dentin between regular and self-adhesive resin cements and to verify the influence of several variables on the retention of GFPs. This report followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. In vitro studies that investigated the bond strength of GFPs luted with self-adhesive and regular resin cements were selected. Searches were carried out in the PubMed and Scopus databases. No publication year or language limit was used, and the last search was done in October 2012. A global comparison was performed between self-adhesive and regular resin cements. Two subgroup analyses were performed: 1) Self-adhesive × Regular resin cement + Etch-and-rinse adhesive and 2) Self-adhesive × Regular resin cement + Self-etch adhesive. The analyses were carried out using fixed-effect and random-effects models. The results showed heterogeneity in all comparisons, and higher bond strength to dentin was identified for self-adhesive cements. Although the articles included in this meta-analysis showed high heterogeneity and high risk of bias, the in vitro literature seems to suggest that use of self-adhesive resin cement could improve the retention of GFPs into root canals.