Accuracy of panoramic radiographic predictor signs in the assessment of proximity of impacted third molars with the mandibular canal

Abstract

Objectives This study aimed to validate the accuracy of panoramic radiographic risk signs through detection of presence or absence of corticalization between an impacted mandibular third molar and the inferior alveolar canal on cone beam computed tomography (CBCT). Methods This retrospective study analyzed 210 impacted mandibular third molars from 135 patients (aged 17–51 years) who showed one or more of the seven previously established panoramic radiographic risk signs of inferior alveolar nerve exposure. These patients were referred for CBCT examination. Three-dimensional images were used to assess the canal position relative to the third molar, the proximity between the canal and third molar, and third molar angulation. The correlation of panoramic findings and CBCT was evaluated using a Chi-square test. Results Panoramic findings of interruption of inferior alveolar canal wall, isolated or combined with one of these signs (darkening of third molar roots, narrowing of canal, and diversion of canal); darkening of the roots; and narrowing of canal were significantly correlated with direct contact between the inferior alveolar canal and impacted third molars on CBCT (P < 0.001). Conclusion Preoperative CBCT is recommended for cases showing interruption of canal wall; darkening of the roots or narrowing of the canal; or association between interruption and narrowing, diversion, or darkening of roots in a panoramic view. This study evaluated the risk relationship between the inferior alveolar nerve and impacted mandibular third molars, with the aim of reducing the occurrence of postoperative injury to the inferior alveolar nerve.

Diversion of the mandibular canal: Is it the best predictor of inferior alveolar nerve damage during mandibular third molar surgery on panoramic radiographs?

“…At our dental faculty, the standard preoperative examination relies on PR. If the radiological signs on PR are suggestive of an close relationship between the LM3 and IAC, additional imaging is recommended for a further examination 8. However, some surgeons routinely obtain preoperative CBCT before LM3 surgery to avoid legal issues.…”

“…However, some surgeons routinely obtain preoperative CBCT before LM3 surgery to avoid legal issues. Although PR does not provide any information regarding the buccolingual dimension,8 it can sometimes be used as the sole preoperative examination for LM3 surgery due to the lower availability of CBCT, especially in developing countries considering their socioeconomic conditions 8. Turkey is a developing country and CBCT is not easy to access in every region.…”

“…Some specific signs that may be obser ved on PRs may suggest a close relationship between the IAC and LM3 8. These radiographic signs include interruption of the mandibular canal wall, darkening of the roots, diversion of the mandibular canal, and narrowing of the mandibular canal 8. The present study aimed to evaluate the relationship between the IAC and impacted LM3 using CBCT and to compare the CBCT findings with signs on PR.…”

“…Determining risk factors before surgery is important for surgeons and patients. Some specific signs that may be obser ved on PRs may suggest a close relationship between the IAC and LM3 8. These radiographic signs include interruption of the mandibular canal wall, darkening of the roots, diversion of the mandibular canal, and narrowing of the mandibular canal 8.…”

Mandibular canal vs. inferior alveolar canal: Evidence‐based terminology analysis

“…The most recent, consecutive 50 articles containing “inferior alveolar canal” or “inferior alveolar nerve canal” were included (defined as the IAC/IANC group) (Adibi, Shahidi, Nikanjam, Paknahad, & Ranjbar, 2017; Afsa & Rahmati, 2017; Al‐Ekrish et al, 2018; Al‐Ekrish et al, 2020; Ali, Mosleh, & Shawky, 2018; Aljarbou, Aldosimani, Althumairy, Alhezam, & Aldawsari, 2019; Arbel et al, 2019; Atef & Mounir, 2018; Česaitienė, Česaitis, Junevičius, & Venskutonis, 2017; Y. Chen, Liu, Pei, Liu, & Pan, 2018; Clark, Barbu, Lorean, Mijiritsky, & Levin, 2017; Demirel & Akbulut, 2020; Dutra et al, 2019; Elkhateeb & Awad, 2018; Ghai & Choudhury, 2018; Goller Bulut & Köse, 2018; Gumusok, Alkurt, Museyibov, & Ucok, 2016; He, Wang, Hu, & Liu, 2019; Ishii, Abe, Moro, Yokomizo, & Kobayashi, 2017; Kablan, Abu‐Sobeh, Lorean, & Levin, 2020; Khojastepour, Khaghaninejad, Hasanshahi, Forghani, & Ahrari, 2019; Kubota, Imai, Nakazawa, & Uzawa, 2020; S. Lee, Lee, Kim, & Nam, 2019; Liu, Sidell, Huon, & Torre, 2018; Luangchana, Pornprasertsuk‐Damrongsri, Kitisubkanchana, & Wongchuensoontorn, 2019; Mortazavi, Baharvand, & Rezaeifar, 2018; Mortazavi, Baharvand, Safi, & Behnaz, 2019; Mortazavi, Baharvand, Safi, Dalaie, et al, 2019; Patil, Pai, Vineetha, Rajagopal, & Dkhar, 2019; Patrick, Birur, Gurushanth, Raghavan, & Gurudath, 2017; Pour, Sedaghati, & Shamshiri, 2020; Prakash et al, 2018; Qi et al, 2019; Rytkönen & Ventä, 2018; Saha, Kedarnath, & Singh, 2019; Şahin, Odabaşı, Demiralp, Kurşun‐Çakmak, & Aliyev, 2019; Sharifi, Beshkar, Mobayeni, & Hasheminasab, 2018; Shokry et al, 2019; Sirin, Yildirimturk, Horasan, & Guven, 2020; Tabrizi et al, 2019; Tachinami, Tomihara, Fujiwara, Nakamori, & Noguchi, 2017; Tudtiam et al, 2019; Uchida, Motoyoshi, Namura, & Shimizu, 2017; Uzun, Sumer, & Sumer,…”