Comparison of crack formation induced by ultrasonic tips and burs during root-end preparation: a systematic review and meta-analysis

SYSTEMATIC REVIEW Comparison of crack formation induced by ultrasonic tips and burs during root-end preparation: a systematic review and meta-analysis Jesseca John,*1 Prabath Singh V. P.,1 Vineetha Karuveettil,2 Remya M.,1 Deepthy Subramanian1 and Kaushik Haridas1 Key points • Inadequate apical seal would facilitate bacterial penetration into the pulpal space thereby leading to failure of treatment. • The formation of cracks following rootend preparation results in apical leakage. • In the present review, the statistical analysis revealed higher crack formation during ultrasonic root-end preparation. Abstract Introduction The main objective of root canal treatment is to achieve apical seal. Crack formation during root-end preparation promotes bacterial penetration, thereby leading to failure. This systematic review aims to examine the literature and summarise studies that compare the crack formation induced by ultrasonic tips and burs during root-end preparation. Methods This systematic review and meta-analysis were reported and conducted according to the PRISMA guidelines. The online databases PubMed, Scopus, and Google Scholar were used for data search. In vitro and ex vivo studies conducted up to March 2021 in the English language were included in the review. The risk of bias in the present study was assessed using a customised tool. A random-effects model was used for meta-analysis, χ² values and I² values were used to assess statistical heterogeneity. Meta-analysis was performed using RevMan software Version 5.4. Results A total of 317 records were found from all of the databases and one article was added following hand-searching. Twelve articles were included in the study after the application of the eligibility criteria of which ten articles were included for the meta-analysis. Nine studies showed a medium risk of bias while three studies showed a high risk of bias. The analysis of the crack formation showed a statistically significant difference between the ultrasonic tip and the bur (P = 0.0002). The odds ratio was 2.72 (1.60, 4.65) with a confidence interval of 95% suggesting higher odds of crack formation in the ultrasonic group. Conclusion This review concludes that ultrasonic root-end preparation resulted in higher crack formation than burs. Introduction the inadequate apical seal would facilitate root-end is resected 3 mm from its tip and Endodontic surgery is an alternative for tooth bacterial penetration into the pulpal space.3 perpendicular to the long axis of the root.6 extraction when root canal retreatment has The purpose of the present systematic review According to Arens, a retropreparation failed or is not viable.1 Surgical endodontics and meta-analysis was to compare the ideally should be centred within the root, involves removal of the pathological formation of cracks induced by ultrasonic parallel to the long axis of the root, and periapical tissue, resection, and preparation tips and burs during root-end preparation. have a depth of 3 mm. These objectives are of the root-end and placing a retrofilling Thus this systematic review aimed to difficult, if not impossible, to achieve due material to seal the root canal.2 It is well answer the following question: ‘What is the to the intricacy of the root canal system, known that the apical seal is a key element difference in the crack formation induced handpiece inflexibility, root location, and to achieve success in endodontic surgery as by ultrasonic tips and burs during root-end lack of sufficient root structure or apical preparation?’ bone. Various retropreparation techniques Department of Conservative Dentistry and Endodontics, Amrita School of Dentistry, Amrita Vishwa Vidyapeetham, Kochi, Kerala, India. 2 Department of Public Health Dentistry, Amrita School of Dentistry, Amrita Vishwa Vidyapeetham, Kochi, Kerala, India. *Correspondence to: Dr Jesseca John Email: 1 Submitted 25 September 2021 Revised 26 November 2021 Accepted 2 December 2021 Published 25 November 2022 https://doi.org/10.1038/s41432-022-0823-0 © EBD 2022 Traditionally, microhandpieces and burs and other types of handpieces have been have been used to perform apicectomies proposed to overcome some of these and retropreparations.4 This approach can drawbacks.7 result in nonparallel cavity walls, difficulties In 1957, Richman first introduced the accessing the root tip, and lingual root concept of ultrasonics (US) in endodontics. perforation, among other issues. 5 The Ultrasonics work in the frequency range of objective of retropreparation and filling 25-40 KHz. Later, US handpieces operating after resection is to block the progress of in the low-frequency range of 1-8 KHz microbes and their toxic metabolites from were developed. These low-frequency the root canal system to the periradicular devices were shown to create minimal shear area. During an apicectomy procedure, the stresses, thereby resulting in less tooth 1 SYSTEMATIC REVIEW surface alteration.8 Magnetostrictive and piezoelectric are the two basic methods by which ultrasound is produced and the tips of piezoelectric units are ideal for use in endodontics as it works in a linear motion. Table 1 Search strategy for PubMed No. Search strategy No. 4 Search No. 1 and No. 2 and No. 3 No. 3 (((((((crack*) OR (chipping)) OR (fracture*)) OR (infraction*)) OR (microcrack)) OR (dentin chip*)) OR (root deformation)) OR (root infraction) No. 2 ((((((bur) OR (conventional root-end cavity preparation)) OR (rotary instrument*)) OR (apical cavity preparation)) OR (microhandpiece)) OR (conventional microhead handpiece)) OR (sonic cavity preparation) No. 1 ((((((ultrasonic* tip) OR (ultrasonic retrotip)) OR (ultrasonic*)) OR (ultrasonic cavity preparation)) OR (ultrasonic root-end preparation)) OR (retrograde cavity preparation)) OR (root-end preparation) In endodontics ultrasonics has proven to be useful in the search for hidden canals, removing separated instruments and post, and for root-end filling.9 Nowadays, ultrasonic tips are increasingly being used by clinicians for retropreparation. Ultrasonic tips have a number of advantages when compared to traditional still no consensus on the best technique performed with any type of ultrasonic tip retropreparation with burs and high-speed for retropreparation. The results of this (Smooth stainless steel/diamond-coated/ handpieces, including the ability to prepare review will contribute towards a greater smaller, finely-shaped, and well-centred understanding of the best technique for root- root-end cavities thereby greatly minimising end preparation, sequentially resulting in less the possibility of perforation. Additionally, crack formation and bacterial penetration. • Outcome: The presence or absence of with these devices, retropreparation can be At the time of this systematic review, there cracks caused by ultrasonic tips and burs performed safel (...truncated)