Adjacent Second Molar Research Articles

Effect of impacted mandibular third molar extraction on periodontal microbiota and clinical parameters of adjacent teeth: A randomized clinical trial

It is urgently necessary to clarify the effect of extraction of impacted mandibular third molar (IMTM) on the periodontal tissue of adjacent second molars (ASMs). In this study, the ASM periodontal condition and pathogenic microbes were assessed before IMTM extraction and at 1, 4, 8 and 12 weeks postoperatively. Based on the inclusion and exclusion criteria, our study revealed that IMTM extractions adversely affected distal － periodontal probing depth (dPPD), attachment loss (dAL), plaque index (dPLI) and bleeding on probing (dBOP) within 8 weeks, but these indices gradually normalize after 12 weeks. The subgingival pathogens near the ASMs distal surface, Porphyromonas and Pseudomonas, were significantly increased postoperatively. Moreover, relevance of ASMs clinical indices and subgingival microbes after IMTM extractions was found. In contrast to the situation in chronic periodontitis, the effects of IMTM extraction on dPPD, dAL, dPLI and dBOP of ASMs were mainly correlated with Pseudomonas. Additionally, while the IMTM extractions have adverse distal periodontal indices of ASMs within 8 weeks and increase subgingival pathogens, the modified triangular flap (MTF) had fewer distal periodontal indices and less Pseudomonas. Compared to the traditional envelope flap and triangular flap, the MTF benefits the periodontal health, which could be considered as the priority option for IMTM extractions.

Evaluation of Risk Factors for External Root Resorption and Dental Caries of Second Molars Associated With Impacted Third Molars

Impacted third molars (M3s) may lead to external root resorption (ERR) and dental caries (DC) in the adjacent secondmolars (M2s). The aim of this study was to identify the risk factors for ERR and DC in M2s associated with impacted M3s. We implemented a cross-sectional study and enrolled a sample composed of patients with M3s and M2s present and cone-beam computed tomography (CBCT) scans available for review. If there was contact between the M2 and the adjacent M3 and the border of radiolucency was more distinct, the case was considered ERR. Apart from that, the case was considered DC. Potential predictor variables were defined as age, gender, tooth location, M2-M3 contact, root development in M3, M3 inclination, M3 impaction type, and M3 follicular diameter.Outcomes of the study were DC and ERR in M2s. CBCT was used to detect the presence of DC and ERR in M2s. A total of 250 eligible images of M3s in the upper and lower jaws of 167 patients were included. The mean age of the patients with CBCT images available was 26.08±4years (range, 18 to 40), and 43.6% of the patients were men. Factors associated with a significantly increased frequency of ERR in M2s included maxillary location, presence of M2-M3 contact, and mesioangular inclination (P<.005). DC in M2s was significantly more likely to occur in those with absence of contact between M2 and M3 (P<.005). The results of this study showed an increased risk of ERR to be associated with maxillary molars, mesioangular inclination, and presence of M2-M3 contact. The variable associated with an increased risk of DC was the absence of M2-M3 contact.

Effect of the Surgeon's Dominant Hand on Postoperative Periodontal Status of Adjacent Molars After Removal of Lower Third Molars

The purpose was to investigate the effect of the surgeon's dominant hand and the side (right orleft) of surgical removal of third molars in the mandible on the probing pocket depth and probing attachment level on the adjacent secondmolars. This study included 73 patients (46 female and 27 male patients; average age, 15.9±1.9years) with 146 asymptomatically submucosal (fully covered by oral mucosa) or impacted (completely enclosed by bone) lower third molars surgically removed by a right-handed surgeon. The probing pocket depth and probing attachment level (outcome variables), as well as the gingiva and plaque indexes (other variables), were documented preoperatively and 6months after surgical removal. Descriptive and bivariate statistics were computed, and the P value was set at .05. The mean probing pocket depth decreased by 0.69mm on the lower left second molar and by 0.64mm on the lower right second molar over the follow-up of 6months.The mean attachment gain was 0.45mm for the lower left second molar and 0.40mm for the lower right second molar. The side differences between these changes in probing pocket depth (P=.620) and probing attachment level (P=.545) were not significant. The gingival index (P=.029) and plaque index (P=.007) deteriorated significantly for the lower right compared with the lower left second molar. For a right-handed surgeon, the operated side had no influence on the changes in probing depth and attachment level on the adjacent secondmolars.

What Are the Risk Factors for External Root Resorption of Second Molars Associated With Impacted Third Molars? A Cone-Beam Computed Tomography Study

In relation to an impacted third molar, which is the most frequently impacted tooth, external root resorption (ERR) or dental caries can be seen on the distal surface of the adjacent secondmolar. The purpose of this study was to investigate the risk factors for ERR in secondmolars associated with impacted third molars using cone-beam computed tomography (CBCT). In this cross-sectional study, the presence of ERR on the adjacent secondmolar was investigated retrospectively on sagittal and axial CBCT slices of patients who underwent CBCT examination for diagnostic reasons (surgical removal of third molars, orthodontic assessments, and so on) between 2013 and 2017 at the Necmettin Erbakan University Faculty of Dentistry, Konya, Turkey. The primary outcome variable was ERR (yes or no). Predictor variables included demographic (age and gender) and radiographic (impacted tooth angulation and tooth type) parameters. Given that there are multiple observations per patient (1 to 4 impacted teeth), 1 third molar per patient was selected at random for study inclusion. Statistical analysis was performed using descriptive statistics, the Mann-Whitney U test, and the Pearson χ2 test. Logistic regression analysis was used to determine the risk factors for ERR in secondmolars. The Cohen κ test was used to test intraobserver agreement. The significance level was set at P<.05. Two hundred patients were analyzed, and of the 200 impacted third molars evaluated, 42 (21%) showed ERR. The severity of resorption increased with aging (P<.05). Logistic regression analysis indicated that tooth type and inclination of the third molars could predict the occurrence of ERR associated with an impacted third molar (P<.05). Mesioangular and horizontal inclinations and impacted mandibular third molars posed a greater risk of ERR lesions in adjacent secondmolars than other inclinations (distoangular and vertical) and maxillary third molars.

Effect of Asymptomatic Visible Third Molars on Periodontal Health of Adjacent Second Molars: A Cross-Sectional Study

Evidence that asymptomatic third molars (M3s) negatively affect their adjacent secondmolars (A-M2s) is limited. The present study evaluated the association between visible M3s (V-M3s) of various clinical status with the periodontal pathologic features of their A-M2s. Subjects with at least 1 quadrant having intact first and secondmolars, either with V-M3s and symptom free or without adjacent V-M3s, were enrolled in the present cross-sectional investigation. Periodontal parameters, including plaque index (PLI), bleeding on probing (BOP), probing pocket depth (PPD), and at least 1 site with a PPD of 5mm or more (PPD5+), obtained from M2s were analyzed according to the presence or absence of V-M3s or the status of the M3s. The χ2 test or t test was used to compare the mean PLI, PPD, BOP percentage, and PPD5+ percentage. The association of PPD5+ with V-M3 status was assessed using a multivariable logistic regression model (quadrant-based analysis), and variances were adjusted for clustered observations within subjects. In total, 572 subjects were enrolled in the study, and 423 had at least 1 V-M3. At the in-quadrant level, the presence of a V-M3 significantly increased M2 pathologic parameters, including PLI, PPD, BOP, and PPD5+. When analyzed using a multivariate logistic regression model, impacted M3s and normally erupted M3s significantly elevated the risk of PPD5+ on their A-M2s (odds ratio 3.20 and 1.67, respectively). Other factors associated with an increased odds of PPD5+ were mandibular region and older age. Finally, the patient-matched comparison showed that the percentage of BOP and PPD5+ on M2s increased when V-M3s were present. Irrespective of their status, the presence of V-M3s is a risk factor for the development of periodontal pathologic features in their A-M2s. Although the prophylactic removal of asymptomatic V-M3s remains controversial, medical decisions should be made as early as possible, because, ideally, extraction should be performed before symptom onset.

Nonimpacted Third Molars Affect the Periodontal Status of Adjacent Teeth: A Cross-Sectional Study

Most previous studies of the effect of third molars (M3s) on the health of adjacent secondmolars (A-M2s) have focused on impacted M3s (I-M3s). The purpose of this study was to investigate whether nonimpacted M3 (N-M3s) could affect the periodontal status of A-M2s. In this cross-sectional study, patients (≥18years) who had at least 1 quadrant with intact first and secondmolars and a nonimpacted or absent M3 were enrolled in this study. The periodontal measurements of M2 (6 sites) in the examined quadrants included the gingival index (GI), plaque index (PLI), probing pocket depth (PPD), clinical attachment level (CAL), gingival recession, and bleeding on probing (BOP). The mean GI, PLI, PPD, CAL, and BOP proportion and the proportion with at least 1 site with a PPD of at least 5mm (PPD5+) were compared using the t test or χ2 test. The association of PPD5+ (percentage) or BOP (percentage) with the presence of N-M3s was assessed using a 2-level logistic regression model (quadrant-based analysis). One hundred thirty-five patients (43.7% men; 40.6 ± 11.5yr old) were enrolled in this study. Patients who had at least 1 quadrant with 3 intact molars and an N-M3 were enrolled in group A (105 patients), and patients who had at least 1 quadrant with intact first and secondmolars without an M3 were enrolled in group B (30 patients). The periodontal parameters (ie, GI, PLI, PPD, CAL, BOP, and PPD5+) were markedly greater in group A. When other factors associated with periodontal disease were controlled, N-M3s were associated with the PPD5+ (odds ratio= 6.7) and BOP (odds ratio= 4.0) of the A-M2s. Other factors positively associated with A-M2 PPD5+ were location on the mandible, age older than 35years, and smoking. The presence of N-M3s is a potential risk factor for the development of periodontitis in A-M2s.