Fracture Resistance of Reattached Incisal Fragments with Three Different Tooth Preparation Techniques: An In Vitro Study

Ashwini Raghunath* 

Ravi Nayar PT COLLEGE, Wardha, Maharashtra, India 

*Corresponding author: Ashwini Raghunath, Ravi Nayar PT COLLEGE, Wardha, Maharashtra, India
 
Citation: Raghunath A. (2022) Fracture Resistance of Reattached Incisal Fragments with Three Different Tooth Preparation Techniques: An In Vitro Study. J Oral Med and Dent Res. 3(2):1-08.

Received: September 23, 2022 | Published: October 12, 2022

Copyright^© 2022 genesis pub by Raghunath A. CC BY-NC-ND 4.0 DEED. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non-Commercial-No Derivatives 4.0 International License., This allows others distribute, remix, tweak, and build upon the work, even commercially, as long as they credit the authors for the original creation.

DOI: https://doi.org/10.52793/JOMDR.2022.3(2)-26

Abstract

Context: In today’s era of evident-based minimally invasive dentistry, reattachment of the fractured crown fragment of a traumatized anterior tooth has become the most favourable treatment option.

Aim: The aim of this in-vitro study was to compare and evaluate the fracture resistance of sound maxillary incisor teeth reattached using different tooth preparation techniques, namely, circumferential chamfer, vertical groove with fibre reinforced composite (FRC) post and internal dentin groove.

Material and Methods: Sixty sound permanent maxillary incisors were mounted in acrylic blocks and divided randomly into four groups (n = 15). In Group A, 15 teeth were retained as positive control in normal saline. The remaining three groups where fragment was to be reattached, a standardized section was prepared through the middle third of crown, perpendicular to long axis of tooth with a water-cooled low speed diamond disc to simulate Ellis and Davey Class II fracture. In Group B, subsequent to reattachment with composite, a 1 mm deep circumferential chamfer was prepared on the fracture line using a diamond bur and restored with composite. In Group C, two vertical grooves 1 mm deep, 1 mm wide, and 4 mm in length were prepared on the labial surface perpendicular to the fracture line. Two fibre‑reinforced composite (FRC) posts were placed in the grooves and restored with composite. In Group D, dentin was removed from the fractured fragment, filled with composite an onscreen calibration tool of the universal testing machine was used to record the force required to fracture the reattached fragment and the fractured specimens were examined under stereomicroscope.

Statistical analysis: One-way ANOVA was used for comparison of three groups (p value <0.05 is considered significant). For the multiple comparison, Tukey’s Post Hoc test was used (p value <0.05 is considered significant).

Results: Teeth in Groups B, C, and D required lesser force to fracture when compared to the teeth in Group A.

Conclusions: The reattachment techniques used in this study resulted in fracture resistance lower to that of intact teeth; vertical grooves with fibre reinforced composite (FRC) post showed superior result compared to the other techniques.

Key Messages: Recent developments in restorative materials, adhesive protocols and preparation designs have allowed clinicians to predictably reinstate fractured teeth. With the advent of adhesive dentistry, reattachment using the patient’s own tooth fragment has become a simplified and more reliable treatment option.

Keywords

Dental trauma; Fibre-reinforced composite post; Fragment reattachment; Permanent tooth

Introduction

The prevalence of maxillary central incisor teeth being injured in any trauma to the facial region is 37%, attributable to their anterior placement in the arch and protrusive eruptive pattern, followed by maxillary lateral incisors (16%) and mandibular central incisors [1]. Most common form of traumatic dental injuries are the crown fractures of permanent dentition. One of the greatest challenges to a dentist is the aesthetic rehabilitation of fractured anterior teeth [2].

Following trauma immediate replacement of lost tooth structure is desired and reattachment of fractured teeth segments is one such treatment option. Improvement in adhesive techniques and restorative materials has made reattachment of dental fragment possible [3]. Reattachment procedures have better prognosis with promising long-term consequences due to the current notions of dentine hybridization. Incisal function, natural translucency and surface texture are reinstated by reattachment. It also provides superior aesthetics, favourable emotional and social response and is relatively simple, atraumatic, and inexpensive procedure [4]. Fragment reattachment is a provisional recuperative technique with a durability of 2-7 years as stated by the IADT guidelines (2020) [5]. The preparation method and the material used for bonding have substantial effects on the strength of such refurbished teeth [6].

The aim of this in-vitro study was to evaluate and compare the fracture resistance of reattached incisal fragments of sound maxillary incisor teeth using three different tooth preparation designs: circumferential chamfer, vertical grooves with fibre reinforced composite (FRC) posts and internal dentin groove.

Materials and Methods

Sixty human non-carious freshly extracted permanent maxillary central incisors were collected. The teeth were meticulously cleaned free of debris and calculus using scalers and stored in normal saline at room temperature. The samples were randomly divided into four groups (n=15) and embedded in standardized jigs using self-cure acrylic till the level of cement enamel junction parallel to long axis of the jig.

Sample Preparation

In Group A15 teeth were kept as positive control in normal saline. A water-cooled low speed diamond disc was used to simulate the Ellis and Davey Class II fracture, cutting through the middle third of the crown perpendicular to the long axis of the tooth in the remaining three groups.

Sample Restoration

Group A: Positive control group. The intact teeth were not sectioned.

Group B: Fractured fragment was reattached using Single Bond Universal adhesive (3M ESPE, St. Paul, MN, USA) andFiltek Z350 XT Universal Restorative body shade(3M ESPE, St. Paul, MN, USA)and cured in stages. 

A 1 mm deep circumferential chamfer was prepared on the fracture line using a diamond bur with depth marker and restored with the same composite.

Group C: Following reattachment, two vertical grooves, 1mm deep, 1mm wide and 4mm in length were prepared on the labial surface perpendicular to fracture line using high-speed depth orientation diamond bur. After applying the adhesive, two 4 mm length FRC posts were placed in the grooves. The space between the FRC post and surface of the tooth was restored with composite and light-cured.

Group D: The entire dentin portion of the fragment was removed using high-speed airotor diamond bur. After application of the adhesive, the area where the dentin was removed was filled with dental composite, reattached, and cured.

Evaluation

The specimens were mounted in the universal testing machine(Tecsol-TSI-BDS) (Figure 2A) at 45° to the horizontal plane, and the load was applied in the labial to lingual direction at 1mm/min in the centre of the restoration using a reinforced stainless-steel wedge (Figure 1, 2B). The force required to fracture the tooth was recorded using an onscreen calibration tool (Figure 2C). 

Figure 1: Methodology A) Sectioning the sample, B) Circumferential Chamfer Technique, C) Vertical Grooves with Fiber Reinforced Composite Post Technique, D) Internal Dentin Groove Technique.

Figure 2: A) Universal Testing Machine, B) Load applied on the mounted sample, C) Fractured sample.

Stereomicroscopic Evaluation for Mode of Fracture

The samples were analysed for mode of fracture under stereomicroscope (Stemi DV4: Carl Zeiss, Gottingen, Germany) at 3.5x magnification and was categorized as one of the two characteristic failure modes: adhesive fracture at tooth-restoration interface and cohesive breakage of the remaining part of the tooth (Figure 3).

Figure 3: Stereomicroscopic evaluation for mode of fracture A) Intact, B) Circumferential Chamfer, C) Vertical Grooves With FRC Posts and D) Internal Dentin Groove.

Results

The data were collected, tabulated, and subjected to statistical analysis using Statistical Package for Social Sciences (SPSS) version 23 (IBM, Chicago, US). One-way ANOVA was used for comparison of three groups (p value <0.05 is considered significant). Continuous variable were described in terms of mean and standard deviation. For the multiple comparison of groups, Tukey’s Post Hoc test was used (p value <0.05 is considered significant). When compared to group A, all the teeth in Groups B, C, and D required lesser force to fracture as shown in Table 1.

Table 1: Comparison of shear bond strength for the four groups.

Table 2 gives the intergroup comparison which revealed that the force needed to fracture the teeth in Group B and Group D was significantly lesser to the force required to fracture the teeth in Group A (P<0.05), but not when compared with Group C (P=0.945).

Table 2: Multiple comparison using Tukey post hoc test.

Discussion

References