ENDODONTICS
Original Articles
A RADIOGRAPHIC STUDY TO DETERMINE THE POSSIBLE EXISTENCE OF A“ SAFE ZONE” AGAINST ENDODONTIC PERIAPICAL EXTRUSION IN THE LOWER PREMOLAR
Wei Cheong Ngeow 1a *, Dionetta Delitta Dionyssius 1b, Hayati Ishak 1b
1
Department of Oro-Maxillofacial Surgical and Medical Sciences, Faculty of Dentistry, University of Malaya, Kuala Lumpur, Malaysia a
BDS( Mal), FFDRCS( Ire), FDSRCS( Eng), MDSc( Mal), PhD( Sheffield), FAMM b
BDS( Mal)
Received: March 09, 2016
Revised: May 30, 2016 Accepted: June 29, 2016 Published: July 01, 2016
Academic Editor: Paula Perlea, DMD, PhD, Associate Professor, Dean,“ Carol Davila” University of Medicine and Pharmacy Bucharest, Bucharest, Romania
Cite this article: Ngeow WC, Dionyssius DD, Ishak H. A radiographic study to determine the possible existence of a“ safe zone” against endodontic periapical extrusion in the lower premolar. Stoma Edu J. 2017; 4( 2): 108-113.
ABSTRACT DOI: 10.25241 / stomaeduj. 2017.4( 2). art. 3
Introduction: Studies have shown that the most common position of the mental foramen in several Asian populations was in line with the apex of the second premolar. Therefore, we seek to determine the average distance of the mental foramen to the apex of the second premolar by using the crown length of the second premolar as a ruler. We hope to define a“ safe zone” in this region. Methodology: Measurements were made from the apex of the second premolar to the mental foramen of ninety seven dental radiographs fulfilling the criteria set. Results: Non-detection of mental foramina happened significantly more often in female subjects than male( Pearson Chi-square; p = 0.01). Of the mental foramina that were visible, 96 % were found to be located within one-crown distance from the apex. More mental foramina( 37.1 %; 56 sites) were located at the apex than any other locations. This is followed by finding the mental foramina located at ¼-crown distance from the apex( 26.5 %; 40 sites). The visibility of the mental foramen was found to be significantly limited in females and in patients aged 50 and above( Pearson Chi-square; p < 0.05). Conclusion: These findings suggest that there is no safe zone against accidental extrusion of endodontic files and materials in the second premolar region. Keywords: endodontology, complication, inferior alveolar nerve, mental nerve, mental foramen.
1. Introduction The mental foramen is located close to the mandibular premolars, especially the second premolar. 1 A morphometric study by Philips et al. 2 reported the mental foramen to be located on average at a distance of 2.18 mm mesially and 2.4 mm inferiorly from the plain radiographic apex of the second premolar. More precisely, the mental foramina could be located anywhere 3.8 mm mesially 2.7 mm distally, 3.4 mm above or 3.5 mm below the apex of the second premolar. Various cadaveric studies reported the apices of the second premolars to be between 0 and 4.7 mm away from the mental foramen. 3, 4 Using a newer technology of cone beam computed tomography( CBCT), BÜrklein et al. 5 also reported similar findings, with an average distance of 4.2 mm. However, 3.2 % of the mental foramen was directly in contact with the second premolar. Because of this close proximity, various events affecting the second premolar, such as odontogenic infection and orthodontic, endodontic, periodontal or surgical misadventure, may result in the neurosensory disturbance to the area innervated by the mental nerve that exits the mental foramen. 1, 6 A retrospective study found an incidence of 0.96 % of mental paraesthesia related to root canal treatment of mandibular premolar teeth. However, all these incidents were related to periapical infection or pathology, instead of being a complication of the root canal treatment itself as the authors excluded 2( 0.24 %) cases of severe overfill and iatrogenic root perforation with mechanical instrumentation into the mental nerve. 3 Eliminating infection in the pulp and dentin, followed by adequate intra-canal preparation and proper sealing constitute the basic principles of root canal treatment. Ideally, mechanical preparation and filling should be limited within the root canal as overinstrumentation or the extrusion of chemical fillings beyond the apical foramen to the adjacent nerve can give rise to NSD such as paraesthesia or anaesthesia. 7, 8 Paresthesia related to overinstrumentation usually resolves within several days. 9 In addition, minor material extrusions are generally well tolerated by the periradicular tissues as long as they do not spread to the adjacent nerve. 10 However, long-term NSD has been reported in cases where the nerve fibre is lacerated due to overinstrumentation or in contact with toxic overfilled endodontic materials. 8, 11
* Corresponding author:
Professor Dr Wei Cheong Ngeow, Department of Oral & Maxillofacial Clinical Sciences, Faculty of Dentistry, University of Malaya, 50603 Kuala Lumpur, Malaysia Tel: 603-79674862, Fax: 603-79674534, e-mail: ngeowy @ um. edu. my
108 Stoma Edu J. 2017; 4( 2): 108-113 http:// www. stomaeduj. com