Lingual bone thickness in the apical region of the horizontal mandibular third molar: A cross-sectional study in young Japanese

Risk Factors Associated With Inferior Alveolar Nerve Injury After Extraction of Impacted Lower Mandibular Third Molars: A Prospective Cohort Study

BACKGROUND

Inferior alveolar nerve (IAN) injury is one of the complications of impacted lower mandibular third molar (LM3) extraction. Given the unknown prognosis of IAN injuries and limited treatment options, it is critical to understand the risk factors of IAN injury before LM3 extraction.

PURPOSE

The purpose of the study was to identify risk factors associated with IAN injury after LM3 extraction.

STUDY DESIGN, SETTING, SAMPLE

This was a prospective cohort study including patients who underwent LM3 extraction from May to December 2021 at the authors' institution. Patients with systemic diseases, previous maxillofacial surgeries, or sensory abnormalities were excluded.

PREDICTOR VARIABLE

The predictor variable is composed of several risk factors. The variables were grouped into four categories: demographic, radiographic, procedure-related, and surgeon experience.

MAIN OUTCOME VARIABLE(S)

The outcome variable was postoperative neurosensory disturbance coded as present or absent and was measured at 1-month (transient) and 1-year (permanent).

COVARIATES

Not applicable.

ANALYSES

The measurement data were represented by mean and standard deviation. The association of each variable with the presence of an IAN injury was tested by the χ2 test. Statistical significance was accepted at P < .05.

RESULTS

The study sample consisted of 705 patients (37.0% male) with an average age of 28.51 ± 6.51 years. A total of 17/705 (2.4%) and 4/705 (0.57%) patients developed transient and permanent IAN injuries. The results demonstrated that the following factors were associated with higher rates of transient injury: use of chisels during surgeries (6.4%; 95% confidence interval (CI): 2.7 to 12.3; P = .02; relative risk (RR) = 11.4), LM3s located below the IAN canal (8.7%; 95% CI: 4.3 to 15.7; P < .01; RR = 7.3), compressed contact between LM3s and the IAN canal (36.4%; 95% CI: 12.3 to 78.2; P < .001; RR = 25.4), and not using corticosteroids after surgeries (3.8%; 95% CI: 1.9 to 6.5; P = .03; RR = 3.1). The only factor associated with permanent injury was compressed contact between LM3s and the IAN canal (18.2%; 95% CI: 2.2 to 62.3; P < .001; RR = 48.2).

CONCLUSION AND RELEVANCE

Close proximity between LM3s and IAN canal and the use of chisels increase the risk of transient IAN injury. Corticosteroid treatment may promote nerve recovery. Compressed contact between LM3s and IAN canal is the only risk factor for permanent injury.

Risk factors for impacted lower third molar root perforation through the undercut-shaped lingual plate: preoperative insights from panoramic radiography

This study aimed to identify risk factors associated with perforation of the undercut (U)-shaped lingual plate (LP) by the lower third molar (LM3) root using panoramic radiography (PAN). We retrospectively examined 468 impacted LM3s from 468 individuals, categorizing LM3-LP associations and LP morphology in the coronal section of cone-beam computed tomography as perforation or nonperforation and U-type or non-U-type, respectively. The outcome was the combination of perforation and U-type, and study variables included patient demographics (age and sex) and PAN-associated features (Winter's classification, Pell-Gregory classification, and two major Rood signs). Multivariate logistic regression methods were used for analysis. Perforated and U-type LPs were observed in 205 (43.8%) and 212 (45.3%) cases, respectively. The double-positive outcome was observed in 126 LM3s (26.9%). In the multivariate model, age ≥ 26 years [odds ratio (OR), 2.66; p = 0.002], men (OR, 2.01; p = 0.002), mesioangular (OR, 2.74; p = 0.038) and horizontal impaction (OR, 3.05; p = 0.019), and root darkening (OR, 1.73; p = 0.039) were independently associated with the risk. Class III impaction (OR, 0.35; p = 0.021) and interruption of the white line (OR, 0.55; p = 0.017) were negatively correlated with the risk. In conclusion, this study highlights the importance of identifying the higher probability of U-type LP perforation by the LM3 root in men aged over their midtwenties with Class I/II impaction and mesioangularly or horizontally impacted LM3s, along with root darkening and no interruption of the white line on PAN.

A preliminary study on the assessment of pain using figures among patients administered with dental local anesthesia for mandibular third molar extraction

The aim of this study was to clarify or determine any possible association between pain reports with a visual analogue scale (VAS) and a figures based scale. This research was a preliminary study aimed at developing a new pain scale without any verbal description. Healthy Japanese patients aged 20 to 39 years who received anesthetic injections for mandibular third molar extraction at our department were enrolled. Regarding pain from dental local anesthetic injections, we recorded figures selected by participants (among options of a circle, triangle, square, bar, and cross), and VAS scores. Overall, 29 men and 31 women participated in the study. Pain caused by local dental anesthesia tended to remind both men and women of the triangle among the suggested figures. Furthermore, patients who chose a cross also reported higher VAS scores than those who chose other figures. Acute pain caused by local dental anesthesia was associated with triangles, and patients who selected a cross were associated with higher VAS scores. The results of this study provide clinicians with important information for dental practice, and could prove useful in developing new pain scales.

Comparison of Short-Term Restorative Effects and Periodontal Health Status of Restorations Made of Different Materials in Full-Crown Restoration of Mandibular Premolar Tooth Defects

Purpose

To compare the short-term restorative effect and periodontal health status of restorations with different materials in full-crown restoration of mandibular premolar tooth defects.

Methods

A total of 105 cases (123 affected teeth) of mandibular premolar tooth defects who visited the Department of Stomatology between January 2019 and January 2020 were selected, of which 58 cases (68 affected teeth) restored with cobalt-chromium alloy porcelain crowns were included in the metal-ceramic crown (MCC) group and 47 cases (55 affected teeth) repaired by zirconium dioxide all-ceramic crowns were assigned to the zirconia crown (ZC) group. The restorative effect, inflammatory factors (high-sensitivity C-reactive protein (hs-CRP) and tumor necrosis factor-α (TNF-α)) and periodontal health indicators (human cartilage glycoprotein-39 (YKL-40), resistin, aspartate aminotransferase (AST), and alkaline phosphatase (ALP)) after treatment, and the occurrence of adverse reactions were compared between the two groups.

Results

The ZC group outperformed the MCC group in terms of margin fitness, restoration fracture, gingival condition, and color matching. After restoration, hs-CRP and TNF-α were statistically decreased in both groups, while YKL-40, resistin, AST, and ALP were significantly increased; and compared with the MCC group, hs-CRP, TNF-α, YKL-40, resistin, AST, and ALP were lower in the ZC group. The ZC group also scored statistically higher in retention effect, aesthetic effect, masticatory function, voice function, and comfort. Moreover, the ZC group had a higher total effective rate and a lower incidence of adverse reactions than the MCC group, with statistical significance.

Conclusions

Zirconia dioxide all-ceramic crowns contribute to a better short-term restorative effect in the full-crown restoration of mandibular premolar tooth defects, with little impact on periodontal health and high patient satisfaction, which deserves popularization and application.