Third Molar and Their Relationship with Caries on the Distal Surface of Second Molar: A Meta-analysis

The Accuracy of Bone Assessment Distal to Lower Second Molars Using Panoramic Radiography: A Systematic Review and Meta-Analysis

Panoramic radiography (OPG) evaluates mandibular third molar impaction (MTMI). This systematic review aimed to investigate the diagnostic accuracy of OPG in detecting bone loss distal to the lower second molars. The associated bone loss with different impaction positions and the most prevalent positions of MTMI were investigated as secondary outcomes. In January 2023, PubMed, Scopus, and Cochrane were searched to identify studies published between January 2012 and January 2023. Two examiners blindly selected the eligible studies for data extraction and quality assessment. Of 427 studies, 8 were suitable for data extraction. All studies reported bone loss distal to the second molar using OPG, ranging from 4.9 to 62.9%. The most frequent position of MTMI is mesioangular. The distal bone loss in the vertical and horizontal positions is statistically significant compared to typically positioned third molars and those that are fully erupted or impacted, but in a normal orientation (p-value 0.005 and 0.02, respectively). Bone loss was not statistically significant in the mesioangular position compared to other impacted positions (p-value 0.14). The risk of bias ranges between 66 and 88%. Despite its limitations, OPG is still considered a valuable tool to assess bone loss distal to the lower second molar in cases of an impacted mandibular third molar.

Spatial Position and Anatomical Characteristics Associated with Impacted Third Molars Using a Map-Reading Strategy on Cone-Beam Computed Tomography Scans: A Retrospective Analysis

(1) Background: This study assessed the spatial position and anatomical features associated with impacted third molars through a map-reading strategy employing cone-beam computed tomography (CBCT). (2) Methods: The positioning of impacted third molars on CBCT was assessed using Winter's and Pell and Gregory's classifications. External root resorption in mandibular second molars was categorized according to Herman's classification. Additionally, the relationship between the mandibular third molar root apex and the mandibular canal was examined. Comparative statistical analysis was conducted using Fisher's exact test, with a significance level considered as 5%. (3) Results: The results indicated that, based on Winter's classification, 48.06 % of impacted teeth were positioned mesioangularly. Employing Pell and Gregory's classification, 43.22% of the impacted molars fell into positions B and C, with 54.2% classified as Class II. A notable 69.7% of teeth exhibited no contact between the root apex and the mandibular canal, and external root resorption in the distal aspect of the second molar was absent in 88.7% of cases. (4) Conclusions: Utilizing the map-reading strategy with CBCT scans to assess the anatomical positions and characteristics of impacted third molars enhances professional confidence and sets a standard for quality and safety in the surgical procedure for patients.

Relationship between the Status of Third Molars and the Occurrence of Dental and Periodontal Lesions in Adjacent Second Molars in the Polish Population: A Radiological Retrospective Observational Study

The aim of this study was to evaluate the effect of third molars on caries, external root resorption, and alveolar bone loss on the distal surface of adjacent second molars. A total of 2488 panoramic radiographs of adult Poles were evaluated. Third molars were classified, according to eruption status, into non-impacted, partially, or completely impacted, and according to angulation into horizontal, mesioangular, vertical, and distoangular. Completely impacted third molars were assigned as reference group. The odds ratios (ORs) and 95% confidence intervals for the occurrence of the above-mentioned pathologies were 1.39 (1.09-2.21), 6.51 (3.72-10.11), and 2.42 (1.22-4.09), respectively, for second molars with adjacent erupted third molars and 1.54 (1.11-2.82), 10.65 (7.81-20.19), and 5.21 (3.38-10.81), respectively, when partially impacted third molars were next to second molars. The ORs of lesions were significantly higher for horizontally and mesioangularly impacted third molars. Within the limitation of a radiological study, it might be concluded that the presence of erupted third molars is a risk factor for caries, while the presence of impacted third molars increases the risk of root resorption and bone loss on the distal surface of second molars.

Top 100 cited publications in the field of third molar surgery: A bibliometric analysis

This study aimed to identify and rank the top 100 cited papers related to third molar surgery METHODS: This bibliometric analysis was performed through the Clarivate Analytics' Web of Science database intended to find the top 100 most cited papers. The search was conducted on 18^th November 2021 with MeSH terms related to the third molar surgery. Extracted Data included title, main author, institution, publication year, a total of citations, citation average per year, country, the journal paper was published, journal impact factor, the number of citations of the three most-cited journals, study design, and field related to third molar surgery RESULTS: The top-cited paper was a retrospective cohort related to complications after the third molars surgery, published in 2003 in the Journal of Oral and Maxillofacial Surgery. The total number of citations was 9026. Thirty-nine percent of the papers included were randomized clinical trials. The USA is the main country responsible for the best publications in the field of third molar surgery. European researchers had the main expressive citation score, and "surgery" related to the third molar was the most critical field of research CONCLUSIONS: 1) The United States of America was the leading country that contributed to third molar field research 2) The Universities of Barcelona and the University of North Carolina were the most productive institutions regarding this research field; 3) Complications after third molar surgery was the most researched field. Compared to the other fields in dentistry such as Oral pathology and Cariology, the number of citations regarding third molar surgery was low.

The Radiological Evaluation of Mandibular Canal Related Variables in Mandibular Third Molar Region: a Retrospective Multicenter Study

OBJECTIVES

The aim of this retrospective study was to investigate anatomical structure of mandibular canal and the factors those increase the possibility of inferior alveolar nerve damage in mandibular third molar region of Turkish population.

MATERIAL AND METHODS

Overall 320 participants with 436 mandibular third molars were included from four different study centers. Following variables were measured: type and depth of third molar impaction, position of mandibular canal in relation to third molars, morphology of mandibular canal, cortication status of mandibular canal, possible contact between the third molars and mandibular canal, thickness and density of superior, buccal, and lingual mandibular canal wall, bucco-lingual and apico-coronal mandibular canal diameters on cone-beam computed tomography scans.

RESULTS

Lingual mandibular canal wall density and thickness were decreased significantly as the impaction depth of mandibular third molar was increased (P = 0.045, P = 0.001 respectively). Highest buccal mandibular canal wall density and thickness were observed in lingual position of mandibular canal in relation to mandibular third molar (P = 0.021, P = 0.034 respectively). Mandibular canal with oval/round morphology had higher apico-coronal diameter in comparison to tear drop and dumbbell morphologies (P = 0.018). Additionally, mandibular canals with observed cortication border and no contact with mandibular third molar had denser and thicker lingual mandibular canal wall (P = 0.003, P = 0.001 respectively).

CONCLUSIONS

Buccal and lingual mandibular canal wall density, thickness and mandibular canal diameter may be related with high-risk indicators of inferior alveolar nerve injury.

Anatomical Positions of Mesially/Horizontally Impacted Mandibular Third Molars are Significant Predictors for Distal Caries in Adjacent Second Molars

Background

Prevalence of distal caries in mandibular second molars (M2Ms) and its relationship with impacted condition of the adjacent mandibular third molars (M3Ms) have been reported in some studies. The results, however, were ambiguous because of including all impaction types and using univariate analysis for statistics.

Aim

This study aimed to determine anatomical features of mesially/horizontally impacted mandibular third molars (M3Ms) that could predict distal caries in the adjacent mandibular second molars (M2Ms) using multivariable analysis.

Materials and Methods

The study sample consisted of 300 digital panoramic radiographs of patients who underwent impacted M3Ms extraction. Two independent researchers collected the following variables from 446 pairs of M2M-M3M: sex, age, status of distal caries in M2Ms, mesial angulation, and Pell–Gregory classification of M3Ms.

Results

The prevalence of distal caries was 50.67%. Multivariable Firth's logistic regression analysis showed that age (β = 0.066, 95% CI = 0.023–0.113), mesial angulation (<30°: β = −1.205, 95% CI = −1.955 to −0.499; >70°: β = −0.730, 95% CI = −1.184 to −0.282), vertical position (level B: β = 2.275; 95% CI = 0.015–7.175; level A: β = 3.008; 95% CI = 0.755–7.905), and horizontal position (level II: β = 1.515; 95% CI = 0.444–2.874; level I: β = 1.423; 95% CI = 0.283–2.825) were significant variables after adjusting for sex in the final model for predicting distal caries (p < 0.05).

Conclusions

In conclusion, anatomical positions of impacted M3Ms, such as mesial angulation and Pell–Gregory classification were significant predictors of distal caries in M2Ms.

To prophylactically extract or not to extract partially erupted mesio-angularly impacted lower third molars?

Introduction Prophylactic removal of mesio-angularly impacted mandibular third molars (MAIM3Ms) has been discouraged by the National Institute for Health and Care Excellence in 2000. Consequently, partially erupted MAIM3Ms are retained for longer and only extracted if complications arise. The debate whether to extract prophylactically or to monitor these teeth is ongoing.Pathologies associated with retained partially erupted MAIM3Ms Retaining third molars long into adulthood has been associated with an increased risk of distal cervical caries and external root resorption of the second molar, periodontal disease and pericoronitis, among other pathologies. Although watchful monitoring can help to identify these pathologies, their nature often leads not only to a poor prognosis for the third molar, but also for the second molar, which then requires costly and time-consuming restorative or even prosthodontic work.Considering prophylactic extractions While an individual risk assessment is paramount, prophylactic removal of partially erupted MAIM3Ms has been shown to have positive effects on oral health-related quality of life, to relieve the pressure on secondary care services and to be economically feasible for the NHS.Conclusion While long-term prospective cohort studies are necessary to put an end to the ongoing controversy, patients' needs and wishes should be at the forefront of the provision of care.

Analysis of Factors Related to Distal Proximal Caries on the Distal Surface of the Mandibular Second Molar Induced by an Impacted Mandibular Third Molar

Objective

To analyze the factors related to distal proximal caries of the mandibular second molar (MSM) induced by an impacted mandibular third molar (MTM).

Methods

A total 500 panoramic radiographs of patients with impacted MTMs who were treated in the Department of Stomatology of the Affiliated Hospital of Yanbian University between October 2017 and October 2019 were selected. Descriptive and bivariate analyses were conducted, and the diagnosis of caries in the MSM and the position of the MTM were evaluated.

Results

The posterior margin space of the MSM was larger in males (13.5 mm) than females (11.1 mm, P < 0.001) and correlated with the MTM’s impacted depth and eruption degree (P < 0.001). The prevalence of distal proximal caries of the MSM was 37.6%, and a χ² test showed that age, impacted depth, impacted direction, impacted angle, degree of occurrence, and CEJ distance were correlated with caries in the distal adjacent surface of the MSM (P < 0.001). Logistic multivariate analysis showed that the impacted depth was at position A or B, the impacted direction was mesioangular, and the impacted angle was <80°. Distal adjacent caries of MSMs were prone to occur when entirely or partially emergent. CEJ distance was not an independent factor for caries. The severity of caries in an MSM’s distal adjacent surface had statistical significance on the impacted depth and impacted angle (P < 0.001).

Conclusion

The posterior margin space of the MSM influences the impacted condition of the MTM. Preventive extraction can be considered if the impacted angle is <80°, especially in the case of a fully or partially emergent MTM at position A or B and mesioangular impacted areas.

Third-Molar Status and Risk of Loss of Adjacent Second Molars

The prophylactic removal of asymptomatic third molars is a common but controversial procedure often rationalized as necessary to prevent future disease on adjacent teeth. Our objective in this retrospective cohort study of adult men was to examine whether second-molar loss differed by baseline status of the adjacent third molar, taking into account the individual's overall state of oral hygiene, caries, and periodontitis. We analyzed data from participants of the VA Dental Longitudinal Study who had at least 1 second molar present at baseline and 2 or more triennial dental examinations between 1969 and 2007. We classified second molars by third-molar status in the same quadrant: unerupted, erupted, or absent. Tooth loss and alveolar bone loss were confirmed radiographically. Caries and restorations, calculus, and probing depth were assessed on each tooth. We estimated the hazards of second-molar loss with proportional hazards regression models for correlated data, controlling for age, smoking, education, absence of the first molar, and whole-mouth indices of calculus, caries, and periodontitis. The analysis included 966 men and 3024 second molar/first molar pairs. Follow-up was 22 ± 11 y (median 24, range 3-38 y). At baseline, 163 third molars were unerupted, 990 were erupted, and 1871 were absent. The prevalence of periodontitis on the second molars did not differ by third-molar status. The prevalence of distal caries was highest on the second molars adjacent to the erupted third molars and lowest on the second molars adjacent to the unerupted third molars. Relative to the absent third molars, adjusted hazards of loss of second molars were not significantly increased for those adjacent to erupted (hazard ratio [HR] = 0.96, 95% confidence interval [CI] = 0.79-1.16) or unerupted (HR = 1.25, 95% CI = 0.91-1.73) third molars. We found similar results when using alveolar bone loss as the periodontitis indicator. Our findings suggest that retained third molars are not associated with an increased risk of second-molar loss in adult men.

Evaluation Distal Caries of the Second Molars in the Presence of Third Molars among Saudi Patients

Objectives:

To evaluate the prevalence of distal caries in second permanent molars in the presence of third molar among patients attending university dental clinics in Riyadh City, Kingdom of Saudi Arabia.

Materials and Methods:

Clinical and radiographic data (orthopantomographs and right and left bite wings) from 313 patients attending Riyadh Elm University dental clinics, department of oral diagnosis were collected and analyzed for the presence of third molars and caries on the distal surface of the second molar. Descriptive statistics of frequency distribution, mean and standard deviation, and binary logistic regression analysis were applied to assess the association between distal surface caries on second molars and impaction status of the teeth.

Results:

The mean decayed, missing, and filled teeth score of the study participants was found to be very high, that is, 23. The prevalence of caries affecting the distal aspect of the second molar was 48.6% (n = 609) in the population. The prevalence of distal caries was significantly high in patients with fully erupted wisdom teeth followed by vertical, horizontal, and mesial impacted third molars (P < 0.05). Wisdom teeth with mesioangular, vertical, and horizontal impactions showed significant association with distal caries of second molars below the contact point, whereas, fully erupted and vertically impacted wisdom teeth showed significant association with distal surface caries of second molars above contact point. Similarly, vertically impacted wisdom teeth were found to have significant association with caries of distal surface of second molars on noncontact areas (P < 0.05).

Conclusion:

This study showed that the distal surface of the second molars is at risk of caries in the presence of third molars. However, this risk depends on eruption status, type of angulation, and contact between third and second molars. All the preventive measures should be taken to avoid caries on distal surface of second molar.

Association between mandibular third molar position and the occurrence of pericoronitis: A systematic review and meta-analysis

OBJECTIVE

The aim of this study was to investigate the association between mandibular third molar position and occurrence of pericoronitis.

DESIGN

The systematic review was performed based on PRISMA criteria (Prospero: CRD42018102835). The electronic search was performed in Medline, Virtual Health Library and Web of Science (until August 2018), without language restriction. Two researchers independently selected studies, extracted data, and assessed methodologic quality. Twenty-one articles were included in the review, comprising 6895 patients, with 1913 third mandibular molars being affected by pericoronitis. Ten studies were incuded in meta-analysis.

RESULTS

The third molar in vertical position of Winter is the one with the greatest chance of presenting pericoronitis, compared to the other positions, while the horizontal position decreases this chance. There was no significant difference in the chance of pericoronitis between positions I and II of Pell & Gregory (OR: 0.29; IC: 0.07-1.23, I² = 88%). Third molars classified in position A had greater chance of pericoronitis when compared to those in position B (OR: 7.13; IC: 1.31-38.74, I² = 93%). The vertical position of the lower third molar is more associated with the occurrence of pericoronitis when compared to the other positions.

CONCLUSIONS

Vertical position of the lower third molar is more associated with the occurrence of pericoronitis when compared to the other Winter' positions. Considering Pell and Gregory positions, position A had a greater chance of pericoronitis compared to position B. The prophylactic removal of lower third semi-erupted vertical molar or in position A is indicated to prevent pericoronitis.

Association between impacted third molars and position of the mandibular canal: a morphological analysis using cone-beam computed tomography

Our aim was to assess the association between the angle of impaction of the third molar and the position of the mandibular canal on cone-beam computed tomography (CT). We designed a retrospective study of 100 cone-beam CT images of 173 mandibular third molars that were obtained between January 2012 and December 2015, and recorded the angle of impaction of the third molar, the position of the mandibular canal in relation to the impacted tooth, and the potential contact between the roots of the tooth and the mandibular canal. Most third molars tilted mesially (n=33), while the mandibular canal was positioned below the roots of the third molar in most cases (n=73). Contact between the two was most likely when the mandibular canal was between (RR=1.49; 95% CI 1.27 to 1.75, p<0.001), or to the lingual side (RR=1.49; 95% CI 1.27 to 1.75, p<0.001) of the roots of the tooth. These outcomes indicate a greater likelihood of contact between the canal and the roots when the canal is between, and to the lingual side, of the roots. We found no association between the angle of impaction and the position of the canal. These findings illustrate the importance of surgical planning using complementary imaging tests such as cone-beam CT.