Three-dimensional position of mandibular third molars and its association with distal caries in mandibular second molars: a cone beam computed tomographic study

Abstract

Objective To analyze the prevalence of distal caries in mandibular second molars (M2Ms) and its correlation with the threedimensional position of mandibular third molars (M3Ms) by cone beam computed tomography (CBCT) images. Materials and methods CBCT scans involving 421 M3Ms were assessed. The presence of distal caries of M2Ms, patient age and gender, impaction depths and mesial angulation of M3Ms, the cementoenamel junction (CEJ) distances and contact point localization, and the horizontal positions of M3Ms were assessed. Risk factors were identified by multivariate logistic regression analysis. Results The overall prevalence of distal caries in M2Ms was 31.6%. Mesial angulation (16°-75°) of M3Ms, contact point localization at or below the CEJ of M2Ms, and a buccal or lingual position of M3Ms relative to the molar line were identified as risk factors for the prevalence of distal caries in M2Ms (p < 0.05). Distal caries was more severe when the mesial angulation of M3Ms was 16°-75°(p < 0.05). Conclusions Buccal or lingual position of M3Ms may represent a new risk factor for the distal caries in M2Ms. Mesial angulation (16°-75°) of M3Ms is a predictive parameter for both the presence and severity of distal caries in M2Ms. Clinical relevance As the presence of distal caries in M2Ms is significantly associated with the three-dimensional position of M3Ms, watchful monitoring or prophylactic removal of M3Ms should be deliberated when M3Ms are mesially angulated (16°-75°), buccally or lingually positioned, and with the contact point localization at or below the CEJ of M2Ms.

Computer-aided three-dimensional assessment of periodontal healing distal to the mandibular second molar after coronectomy of the mandibular third molar: a prospective study

“…Second, defects at DM and DB sites were much deeper than those at the DL site (Table 1), and might have been caused by M3M growth. Chen studied 421 CBCT images of M3Ms and found that 96.2% of M3Ms were at median or buccal sides distal to M2Ms [36]. Conversely, we found that PD reduction could be due more to soft-tissue variation than hard-tissue variation (Table 4).…”

Frequency of external root resorption in mandibular second molars associated with mandibular impacted third molars in a sample of Egyptian population using CBCT: A cross-sectional study

“…(4) Moreover, the association of these risk factors to the development of pathological effects, may add valuable knowledge in the indications for removal of the impacted third molar, (13) as prophylactic removal of impacted third molars still remains controversial in the literature up till now. (5) Cone beam computed tomography (CBCT) provides 3D multiplanar imaging with no superimposition (compared to conventional imaging techniques), low radiation dose and high spatial resolution. (23) Furthermore, CBCT has been used as a diagnostic tool to detect different pathological conditions in second molars associated with impacted third molar.…”

“…(9,18) Therefore, CBCT can provide detailed information of the proximity and relationship of second molars and third molars in the three dimensions, rendering analysis of risk factors of ERR of second molars more accurate. (5) This is the first study to be conducted among Egyptian population using CBCT and it sought to detect the frequency of ERR in second molars adjacent to impacted third molars, and identify the association of this pathological findings with tooth specific and patient specific risk factors.…”

Sex-related variation in the dimensions of the mandibular ramus and its relationship with lower third molar impaction

“…The aetiology of mandibular third molar impaction is unknown, but contributing factors include a discrepancy between tooth and jaw size, ramus width, and the inclination of the lower posterior dentition. 2 In order to assess impaction, various techniques are commonly used, such as panoramic 3 , 4 and cephalometric images, 5 cone beam computed tomography, 6 and magnetic resonance imaging. 7 Of these, panoramic images are considered to be the most cost-effective and provide a broad outline of the dentition with less radiation exposure.…”