Fracture Resistance in Non-Vital Teeth: Absence of Interproximal Ferrule and Influence of Preparation Depth in CAD/CAM Endocrown Overlays—An In Vitro Study

Abstract

There is ample evidence to support the use of endocrowns to restore endodontic teeth. However, the influence of the position of the interproximal margins on fracture strength has not yet been studied. The aim was to determine the relationship between the apicocoronal position of the interproximal restorative margins and fracture resistance in nonvital teeth restored with CAD/CAM endocrown overlays. Forty extracted human maxillary premolars were prepared for endocrown overlay restorations without ferrule on the interproximal aspects and classified according to the position of the interproximal restoration margins in relation to the alveolar crest: 2 mm (group A), 1 mm (group B), 0.5 mm (group C), and 0 mm (group D). Fracture strength was measured using a universal testing machine applying a compressive force to the longitudinal tooth axis. Group A had a mean fracture resistance of 859.61 (±267.951) N, group B 1053.9 (±333.985) N, group C 1124.6 (±291.172) N, and group D 780.67 (±183.269) N, with statistical differences between groups. Group C had the highest values for fracture strength compared to the other groups (p < 0.05). The location of the interproximal margins appears to influence the fracture resistance of CAD/CAM endocrown overlays. A distance of 0.5 mm between the interproximal margin and the alveolar crest was associated with increased fracture resistance.

Endocrown restorations in premolars: influence of remaining axial walls of tooth structure and restorative materials on fatigue resistance

“…Incidence of pulp involvement from extensive interproximal caries is commonly encountered, leading to endodontic treatment. In this situation, one or two proximal walls with intact buccal and lingual walls are often destroyed [22]. To our knowledge, information about the effect of missing proximal walls on the biomechanical behavior of premolars restored with endocrowns are lacking.…”

Indications for the use of endocrowns, design and selection of materials: Literature review

“…Regarding the ferrule of the preparation, the presence of this element improves the resistance of the restoration against fracture, and a 1mm ferrule offers this advantage without presenting a greater risk of catastrophic fracture, as can be seen in those with a 2mm ferrule [18] . The interproximal margin should be as close as possible to the level of the bone crest, ideally with measurements of .5mm or less [19] . A modification to the conventionally used design consists in the use of notches or channels in the mesiobuccal and distolingual dentin wall.…”

Analysis of the Pulpal Blood Flow Microdynamics during Prosthetic Tooth Preparation Using Diamond Burs with Different Degrees of Wear

“…A crucial aspect of successful restorative procedures is to minimize additional irritation to the pulp and avoid disruption to normal pulpal healing. Numerous researchers have asserted that vital teeth exhibit greater resistance to bacterial infiltration into dentinal tubules compared to non-vital teeth [ 2 , 29 , 30 ] and more resilience to fracture than endodontically treated teeth [ 30 ]. This suggests a significant role played by the vital pulp in this process.…”