[Post-endodontic restoration: a direct or indirect restoration?] / De coronale afsluiting: een directe of indirecte restauratie?

When restoring an endodontically treated tooth, it is important to preserve the pericervical dentin so it is resistant especially to lateral forces occurring during mastication. When little pericervical dentin is seen to be present, an adhesive restoration is indicated. Tooth survival of endodontically treated teeth restored with adhesive direct and indirect restorations varies between 90.5% and 95.0% after 5 years. Deciding between a direct or an indirect restoration depends above all on the possibility to predictably restore the anatomy and on gloss retention. Because endodontically treated teeth are vulnerable to lateral forces, control of these forces after direct or indirect restoration is important. This can be achieved by a reduction in the steepness of the cuspal slope and/or by covering the cusps with the restorative material.

[Attitude of graduate dental students in The Netherlands towards rubber dam use]. / Rubberdamgebruik onder vijfde- en zesdejaars tandheelkundestudenten in Nederland.

The use of rubber dam isolation during restorative procedures is often used. This survey study analyzed several aspects of the use of rubber dam isolation of fifth and sixth year's dental students at three Dutch universities using the COM-B model. This model explains behavior (B) from 3 factors: capacity (C), opportunity (O), and motivation (M). In the period of February-August 2022, a total of 81 students completed the survey (Academic Center for Dentistry Amsterdam, ACTA, n = 25; Radboud University, RU, n=28; Center for Dentistry and Oral Hygiene, CTM, n = 28). There were significant differences on all 3 factors between universities. RU students felt more confident than CTM students in applying the rubber dam in the anterior zone. At RU, teachers were significantly less likely to encourage the use of rubber dams. CTM students were more likely to assess the use of rubber dams as more important in the longevity of direct restorations (motivation). Students struggled the most with rubber dam use in subgingival cases and would like that their teachers were more adept in manipulation of soft tissues. Within the Netherlands, the education in rubber dam use should focus more on practical skills in these subgingival cases, including soft tissue handling.

[Adhesive bonding on the endodontically treated tooth]. / Adhesieve hechting aan het endodontisch behandelde gebitselement.

Endodontic irrigants negatively influence the physical properties of dentine. The effect of sodium hypochlorite and ethylenediaminetetraacetic acid (EDTA) on the bond strength to dentine was investigated in a systematic review. Inclusion criteria were the following: a microtensile or microshear test, the irrigants sodium hypochlorite and/or EDTA, an irrigation time of ≥ 5 minutes of sodium hypochlorite, an irrigation protocol for endodontic treatment, human dentine, the presence of a control group and no post space preparation. Of the 188 eligible articles, 13 were suitable for inclusion. There was strong evidence that rinsing with sodium hypochlorite and also additional rinsing minutes with ethylenediaminetetraacetic acid leads to minimum bond strength to dentin for a two-step self-etching adhesive. For a two-step etch-and-rinse adhesive, the bond strength is approximately significant after rinsing with sodium hypochlorite (rinsing time: 10-60 minutes).

[Should a metal post always be replaced before a new indirect -restoration?] / Moet een metalen stift altijd worden vervangen voor plaatsing van een kroon?

Before realizing a new indirect restoration on an endodontically treated tooth, present restorations and possible posts need to be assessed. In the case of a metal post, the mismatch in flexural modulus between the dentine and the post might increase the risk of a vertical root fracture. Is it therefore prudent to replace such a metal post, before the fabrication of a new indirect restoration? Two scenarios might be considered to answer this question. First, would a glass fibre post result in a lower risk of failure? Two systematic reviews of the literature comparing glass fibre and metal posts for the short term were contradictory. Second, is the occurrence of a vertical root fracture associated with the presence of a post? Such association could not be established either. On the basis of the current literature, there does not appear to be evidence to support actively replacing a metal post.

[Restoration choices for endodontically treated posterior teeth]. / Restauratieve keuzes voor endodontisch behandelde gebits-elementen in de posterieure zone.

There aren't any generally accepted guidelines for the restoration of an endodontically treated tooth. With a questionnaire among dental general practitioners and endodontists, several restorative treatment options for endodontically treated molars and premolars were identified. The questionnaire inventoried the influence of various parameters on treatment preferences. For each case, additional questions were put about material choice, cuspal coverage and the use of root canal posts. Both groups identified the vertical root fracture as the most common reason for extraction. The dentist general practitioner waited longer than the endodontist to make a permanent restoration in the case of apical periodontitis. Treatment preferences were found to be the same for premolars and molars. In the case of premolars, a root canal post was indicated more often and the location of the wall (bearing/non-bearing) influenced the choice of cuspal coverage. Of the dentist general practitioners and endodontists, 51-53% and 75-94%, respectively, preferred a partial over a full crown preparation in the case of single-walled teeth.

[Fracture strength of various types of direct and indirect restorations in the functional repair of endodontically treated molars]. / Breuksterkte van verschillende types directe en indirecte restauraties bij het functioneel herstel van endodontisch behandelde molaren.

The fracture strength of endodontically treated molars restored by means of various types of direct and indirect materials was studied in vitro. 105 sound molars were endodontically treated and randomly assigned to 1 control group (endodontic access cavity only) and 6 experimental groups (n = 15) with restorations of the following materials: glass fibre reinforced composite (GFRC); microhybrid composite (C); microhybrid composite restoration with glass fiber post (CP); full-contour lithium disilicate crown (LDS); full-contour lithium disilicate crown with glass fiber post (P-LDS); and an endocrown (EC). Specimens were thermo-mechanically aged and axially loaded until failure. Data were analysed using ANOVA and Tukey's post hoc test (α = 0.05). Fracture strength was significantly affected by the type of restoration (p = 0.000). LDS had significantly higher fracture strength than the control group and GFRC, C and CP groups. Groups EC, LDS and P-LDS were not statistically different from each other in fracture strength. This was also the case with EC, P-LDS and all composite groups. The glass fibre strength of composite restoration resulted in significantly fewer fatal fractures.