The Effect of Different Restoration Techniques on the Fracture Resistance of Endodontically-treated Molars

Abstract

SUMMARYAim: This study compared the fracture resistance of endodontically-treated mandibular molars with mesio-occluso-distal (MOD) cavities restored using different restoration techniques. Methodology: Sixty sound extracted mandibular molars were randomly assigned to six groups (n=10). Group 1 did not receive any preparation.The teeth in Groups 2-6 received root canal treatment and a MOD cavity preparation. The teeth in Group 2 were kept unrestored. Group 3 was restored conventionally with amalgam. Group 4 was restored with a dentin bonding system (DBS, Clearfil SE Bond) and resin composite (CR) (Clearfil Photoposterior). Group 5 was restored with indirect hybrid ceramic inlay material (Estenia). In Group 6, polyethylene ribbon fiber (Ribbond) was inserted into cavities in a buccalto-lingual direction and the teeth were then restored with DBS and CR. After finishing and polishing, the specimens, except for Group 2, were loaded to failure by a chewing simulation device ( To restore endodontically-treated molars, the use of indirect hybrid inlay restorations may be recommended due to their more favorable fracture failure modes compared with amalgam, resin composite and fiber-reinforced resin composite restoration techniques and their greater fracture resistance compared with amalgam restorations. . There were statistically significant differences between the groups annotated with different letters. Thus, Group 1 (intact teeth) had the greatest fracture resistance and Group 2 (non-restored teeth) the poorest. No statistically significant differences were found between Groups 3 (amalgam), 4 (resin composite) and 6 (polyethylene ribbon fiber reinforced composite) (p>0.05). Group 5 (indirect hybrid ceramic inlay) had greater fracture resistance than Group 3 (p<0.05). Conclusions: Within the limitations of this study, although all of the restoration groups were stronger than the prepared-only group, none of the restoration techniques tested was able to completely restore the fracture resistance lost from MOD cavity preparation. However, use of indirect hybrid inlay restorations in these teeth may be recommended, because this restoration technique indicated more favorable fracture failure modes than other restoration techniques used in this study and particularly greater fracture strength than amalgam restorations. The promising result of indirect hybrid inlay restorations may need to be confirmed by long-term clinical studies.

Effects of fiber-glass-reinforced composite restorations on fracture resistance and failure mode of endodontically treated molars

“…Therefore, a restoration technique that can reinforce the weakened remaining tooth structure is fundamental to reducing the possibility of fractures. Moreover, in the selected teeth, standardized MOD cavities were prepared because this clinical condition strongly reduces resistance to cuspal fractures [2,[26][27][28][29] due to the absence of mesial and distal walls, which cause a high strain on vestibular and lingual cusps [18]. Soares et al confirmed that MOD preparation and endodontic treatment accentuated the concentration of stress inside the dental structure, mainly due to the greater removal of the dental structure [30].…”

“…The teeth were stored in distilled water at room temperature for at least 72 h. For the simulation of 0.3-mm-thick periodontal ligament, each root was immersed in melted wax up to the demarcation line 2 mm apical to the cement-enamel junction [18] (CEJ; checked with a digital caliper). A metal cubic mold was used to embed all the specimens in acrylic self-curing resin (StickRESIN; Stick Tech Ltd., Turku, Finland) up to 1 mm apical to the CEJ, their long axes were oriented perpendicular to the horizon using a custom-made parallelometer.…”

“…In particular, ultra-high-molecular-weight polyethylene fiber (PWT), which has an ultra-high elastic modulus, has been tested recently [17,18]. The woven network allows fiber wetting and the infusion of the bonding resin; this enhances the transfer of forces acting on the PWT.…”

Marginal adaptation, fracture load and macroscopic failure mode of adhesively luted PMMA-based CAD/CAM inlays

“…One study of CAD/CAM three-unit polymeric fixed partial dentures (FPDs) observed significantly higher fracture load results compared to glass-ceramics, as well as conventionally polymerised resins, after different aging regimens [8]. In several studies, CAD/CAM fabricated composite overlays and crowns for premolars and molars showed high fatigue resistance and were recommended for long-term reconstructions [9][10][11].…”

Rethinking ferrule – a new approach to an old dilemma

“…87 Although the overwhelming majority of the literature supports the need for full coverage restorations of most endodontic treated teeth, and a strong association between the success of endodontic treated teeth and crowned teeth has been shown, [88][89][90] alternatives have been suggested too. These include using complex amalgam restorations, 91,92 overlays 65 or composite restorations.…”