Effects of ultrasonic root end preparation on resected root surfaces: SEM evaluation

doi:10.1016/j.tripleo.2004.04.004

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology

Volume 98, Issue 5, November 2004, Pages 611-618

https://doi.org/10.1016/j.tripleo.2004.04.004 Get rights and content

Abstract

Objective

The purpose of this study was to investigate the in vitro effect of ultrasonic retrotips on root end surfaces.

Study design

Root end resection was performed on 45 single-root teeth endodontically treated after extraction. Setting the ultrasonic device at full power, a retrograde cavity was made by a stainless steel tip in 9 specimens (SS-FP). In another 9 samples a diamond tip was used (D-FP). Setting the intensity of the ultrasonic device at half power, 9 specimens were treated using stainless steel tips (SS-HP) and 9 using diamond tip (D-HP). Nine teeth were only apically resected and used as controls. Histologic serial sections were examined by scanning electron microsope to assess the number of root-face cracking, the marginal quality, and the crack type.

Results

No significant difference between diamond and stainless steel groups was found at a given power setting. Significant differences were found between SS-FP and SS-HP group for both the number of cracks and the marginal quality.

Section snippets

Material and methods

Forty-five human teeth with single straight roots and single canals were used in this study. All the teeth were vital and extracted for orthodontic and/or periodontal reasons, from subjects aged between 18 and 45 years. Only specimens without restorations, with intact roots and mature apexes free of defects and visible fractures were selected. Following extraction, soft tissue and debris were removed from the surfaces of the roots by hand scaling. The teeth were then thoroughly cleaned and

Results

Table I summarizes the results of the evaluation of the different parameters.

Discussion

Recently, ultrasonic root end preparation techniques for endodontic surgery have gained popularity in endodontics practice. In contrast to bur-prepared root end cavities, those shaped using ultrasonic retrotips are deeper, rarely deviate from the canal space, and require smaller bony crypts and smaller bevel angles for preparation.³⁵

However, any approach that could prevent or minimize adverse effects of the root end preparation such as the occurrence of dentinal cracks should be considered.

Conclusions

1.
Root face cracks number: Comparing diamond-coated and stainless steel tip groups, no significant differences were found in the number of cracks produced at both full and half power setting. In the groups using stainless steel retrotips the FP group showed a significantly higher number of cracks than the HP group.
2.
Type of cracks: No significant difference was found between diamond-coated tips and stainless steel tips at both power setting.
3.
Marginal quality of retrograde cavity: No significant

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The machining of hard tissues, such as cortical bone and cancellous bone in human bodies and enamel and dentin in teeth, is an essential process in orthopaedics, neurosurgery and dentistry. Owing to their natural high hardness and strength, as well as anisotropic composite structure and properties, the machining process is difficult and prone to generating large cutting forces and high temperatures, potentially leading to necrosis (i.e., cellular death) and microcracks and, therefore, tissue damage. Necrosis and microcracks affect the stability of implant fixation and post-surgery recovery. In this paper, studies in tissue structure and properties, cutting mechanisms, and thermal and mechanical damages formed in the machined surface and subsurface have been reviewed to facilitate the understanding of machining processes and mechanisms for hard tissue. Traditional (orthogonal cutting, drilling, milling and grinding) and non-traditional (vibration-assisted) cutting processes have been considered to explore the underlying mechanisms that control the material removal process and understand the damages that may be formed in hard tissues. The solution strategies developed for minimising the machining-induced damages to the tissues have also been evaluated to provide the knowledge needed for improving surgical tool design. Finally, the research gaps have been identified in this study and future research prospects in hard tissue machining have been proposed.
Evaluation of Quality and Preparation Time of Retrograde Cavities in Root Canals Filled with GuttaCore and Cold Lateral Condensation Technique
2018, Journal of Endodontics
The aim of this study was to measure the time consumed preparing retrograde cavities in root canals of maxillary molars filled using the GuttaCore (Dentsply Tulsa Dental Specialties, Tulsa, OK) technique and the cold lateral condensation technique (CLC) and to examine the quality of the root-end cavity preparation by ultrasonic tips using micro–computed tomographic (micro-CT) scanning.
A total of 24 maxillary molars were included; distobuccal and palatal canals were instrumented to size #40 and size #50, respectively. Teeth were randomly distributed into 2 experimental groups; half of the samples were filled with CLC, and half were filled with the GuttaCore technique. After 2 months, the apical 3 mm of each root apex was resected. A retrograde cavity was then prepared 3 mm deep into the root-end–filled canals using ultrasonic tips. The quality of the preparation was first confirmed by a surgical stereomicroscope, and the time required for the root-end preparation was recorded. After root-end cavity preparation, all samples were scanned by micro-CT scanning.
There was no significant difference between the palatal and distobuccal canals in the time required to prepare a retrograde cavity. Less time was required in the GuttaCore group to remove all root filling material and finish the cavity preparation than in the CLC group (P < .05), especially in the palatal canals. Micro-CT results confirmed that all material was removed from the root-end cavities and the absence of microcracks.
GuttaCore was removed in less time from root-end cavities than root filling performed with the CLC technique. No damage to the surrounding dentin was detected by micro-CT scanning in the 2 groups.
Applications of piezoelectric surgery in endodontic surgery: A literature review
2014, Journal of Endodontics
Citation Excerpt :
Despite the excellent results obtained with ultrasonic retrotips, some drawbacks are associated with their use (62). For example, several studies (59, 63–67) have shown the occurrence of dentinal cracks on resected root ends after retrograde preparation with ultrasonic retrotips. However, these in vitro studies had limitations.
Piezosurgery (piezoelectric bone surgery) devices were developed to cut bone atraumatically using ultrasonic vibrations and to provide an alternative to the mechanical and electrical instruments used in conventional oral surgery. Indications for piezosurgery are increasing in oral and maxillofacial surgery, as in other disciplines, such as endodontic surgery. Key features of piezosurgery instruments include their ability to selectively cut bone without damaging adjacent soft tissue, to provide a clear operative field, and to cut without generating heat. Although piezosurgery instruments can be used at most stages of endodontic surgery (osteotomy, root-end resection, and root-end preparation), no published data are available on the effect of piezosurgery on the outcomes of endodontic surgery. To our knowledge, no study has evaluated the effect of piezosurgery on root-end resection, and only 1 has investigated root-end morphology after retrograde cavity preparation using piezosurgery.
We conducted a search of the PubMed and Cochrane databases using appropriate terms and keywords related to the use and applications of piezoelectric surgery in endodontic surgery. A hand search also was conducted of issues published in the preceding 2 years of several journals. Two independent reviewers obtained and analyzed the full texts of the selected articles.
A total of 121 articles published between January 2000 and December 2013 were identified. This review summarizes the operating principles of piezoelectric devices and outlines the applications of piezosurgery in endodontic surgery using clinical examples.
Piezosurgery is a promising technical modality with applications in several aspects of endodontic surgery, but further studies are necessary to determine the influence of piezosurgery on root-end resection and root-end preparation.
Evaluation of root-end preparation with a new ultrasonic tip
2013, Journal of Endodontics
Citation Excerpt :
We found that the quality of preparation was better when using new instruments compared with the quality produced by the same instrument after 10 uses, similar to the findings of Taschieri et al. The occurrence of microcracks has been repeatedly reported in ultrasonic retropreparation (22–25). Possible factors related to microcracks include the following: the type of tip that was used, the power settings of the unit, the amount of time necessary to prepare the cavities, and the presence or absence of initial microcracks.
This study was conducted to evaluate the effect of a new ultrasonic tip (Jetip) for root-end preparation.
A total of 80 single-rooted teeth were endodontically treated, and the apical 3 mm of the root apex was resected. Teeth were randomly distributed into 2 experimental groups according to the ultrasonic tips used to prepare the root-end cavity. Epoxy resin replicas of root-end surfaces after root-end resection were obtained. A root-end cavity was then prepared with an ultrasonic tip, either Jetip or AS3D. Replicas of the apices were fabricated after the retropreparations, and they were processed for analysis by scanning electron microscopy (SEM) to evaluate the presence of microcracks and the quality of the root-end preparation. The morphologic characteristics of the ultrasonic tip were also assessed by SEM. The time required for root-end preparation was recorded.
There were no statistically significant differences between the Jetip and AS3D groups in the mean time for the root-end preparation, the incidence of microcracks, or the quality of the root-end preparation (P > .05). SEM analysis showed that Jetip exhibited smoothed microprojections after the root preparations, whereas the loss of diamond particles was observed in AS3D.
Both Jetip and AS3D provided rapid and regular root-end preparations. The cutting efficiencies of both Jetip and AS3D decreased with the number of times the tips were used. The Jetip showed smooth microprojections after root-end preparation, whereas the AS3D tip exhibited the loss of diamond particles.
Removal of surgical smear layer
2011, Journal of Endodontics
During apicoectomy and retrograde cavity preparation, a smear layer, which contains microorganisms and necrotic pulpal tissues, is formed on the dentinal surfaces cut by the instruments. Bacteria can survive and proliferate inside or below the smear layer. The purpose of this study was to evaluate in vitro two different procedures for the removal of the smear layer in retrocavities prepared with ultrasonic retrotips.
Twenty-eight single-rooted teeth were cleaned, shaped, and obturated with gutta-percha and sealer. The apical 3 mm of each root were cut with a carbide bur, and retrograde cavities were prepared with ProUltra ultrasonic retrotips (Maillefer Dentsply, Baillagues, Switzerland) at a depth of 3 mm. Teeth in group A were treated with a gel of 35% orthophosphoric acid for 15 seconds, and teeth in group B were treated with a gel of 24% EDTA at a neutral pH for 2 minutes. The samples were prepared for scanning electron microscopic observation and scored for the presence of the smear layer on the retrocavity walls.
Eighty percent of the teeth in group A showed an optimal degree of cleanliness of the walls, with dentinal tubules completely open. The majority of analyzed samples coming from group B showed dentinal tubules covered with the smear layer.
The analysis of the samples showed that orthophosphoric acid is more effective than EDTA in removing surgical smear layer even with less time of action.
An in vitro evaluation of apicoectomies and retropreparations using different methods
2010, Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology and Endodontology
Citation Excerpt :
Therefore, in the present study the laser power was reduced to 3.5 W. The possibility of fissures in the apical surface is a concern during the use of the ultrasound for preparing the retrograde cavities.17 The only study that used CVD tips in apicectomies reported the absence of fissures when using medium power,11 which corroborates our findings of using similar power settings.
The aim of this study was to evaluate: 1) the apical root surface, gutta-percha interface, and preparation time of root-end resections made with burs, ultrasound, or laser; and 2) the thickness of surrounding dentin after laser or ultrasonic root-end cavity preparation.
1) Thirty root-filled teeth were resected as follows: Zekrya bur in group I, Chemical Vapor Deposition (CVD) ultrasonic tip (9.5107-8) in group II, and ErCr:YSGG (Waterlase) in group III. The preparation time was recorded. Replicas of the resected root-ends were examined under a scanning electron microscope (SEM). 2) Thirty root-filled teeth were submitted to apicectomies and root-end cavities were prepared by using: CVD (6.1107-6) ultrasonic retrotips (group IV), EMS (DT-060) ultrasonic retrotips (group V), and ErCr:YSGG laser tips (group VI). Replicas of the root apices were examined under a SEM.
There were no fissures or fractures on root-end surfaces. The bur produced the smoothest surface (P < .05). Group I had the lowest preparation time (P < .05). The best adaptation between the filling and the root canals walls was observed in group III, but it was not significantly different from group II (P < .05). No resected root-ends had cracks after preparation. Group VI showed the least minimum dentin thickness (P < .05).
The 3 methods evaluated did not cause any injury to the root-end surface, but they harmed the apical adaptation. Laser tips removed more dentin than ultrasonic retrotips and should be used with care to avoid overpreparation.

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EndodontologyEffects of ultrasonic root end preparation on resected root surfaces: SEM evaluation

Abstract

Objective

Study design

Results

Section snippets

Material and methods

Results

Discussion

Conclusions

J Endod

J Endod

J Oral Maxillofac Surg

J Endod

Oral Surg Oral Med Oral Pathol Oral Radiol Endod

J Oral Maxillofac Surg

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J Endod

J Endod

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J Endod

J Endod

J Endod

J Endod

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Arch Oral Biol

Biomaterials

Endodontology
Effects of ultrasonic root end preparation on resected root surfaces: SEM evaluation