Association between mandibular third molar impaction patterns, second molar caries, and pericoronitis: a cross-sectional study in a syrian population

Abstract

Purpose

The purpose of this study was to investigate the pattern of mandibular third molar impaction and its association with distal carious lesions of adjacent mandibular second molars (MSMs), as well as the occurrence of pericoronitis, in a Syrian population.

Methods

This cross-sectional study included 619 mandibular third molars (MTMs) from 365 Syrian patients. The pattern of impaction was assessed clinically and radiographically using Winter’s classification and Pell & Gregory’s classification. The presence of distal caries on adjacent mandibular second molars and the occurrence of pericoronitis were recorded. Information on patient age and gender was also collected. Associations between impaction patterns and the presence of distal caries and pericoronitis were statistically analyzed, with p < 0.05 considered significant.

Results

Among the 619 MTMs evaluated, 418 were in females and 201 in males. The most common age group was 21–25 years (40.8%). Mesioangular impaction was the most frequent type (55.3%), and Class A impaction was the most prevalent (64%). Pericoronitis occurred in 5.7% of cases and was significantly associated with age (p = 0.020), vertical impaction (p = 0.010), and Class A molars (p = 0.001). Distal caries was observed in 12.6% of cases, mainly in patients older than 26 years, with no significant gender difference (p = 0.791); the highest prevalence was found in Class A molars.

Conclusions

The anatomical position and angulation of impacted mandibular third molars significantly influence the risk of pericoronitis and distal caries. This finding suggests that prophylactic removal of these molars may help reduce associated complications.

Introduction

Permanent third molars, also known as wisdom teeth, are typically located in the posterior regions of the jaws and erupt into the mouth between 18 and 25 years of age. In some cases, these teeth may emerge only partially - referred to as being partially impacted - or may fail to erupt through the gums and bone entirely, a condition known as being fully impacted (Ahire et al. 2016; Saisha et al. 2023). Mandibular third molars (MTMs) are the most frequently impacted teeth, with reported incidence rates ranging from 30.3% to 68.6% (Srivastava et al. 2017). The primary causes of third molar impaction include abnormal developmental positioning and insufficient space between the ascending ramus and the second molar for proper eruption (Srivastava et al. 2017).

Several methodologies have been employed to assess the impact of impacted MTMs. Pell and Gregory developed a system to classify mandibular third-molar impaction using two criteria. The first criterion gauges the depth of impaction in relation to the occlusal plane of the neighboring second molar and is divided into three categories: A, B, and C. The second criterion assesses the position of the impacted tooth relative to the anterior border of the ramus and is classified as Class I, II, or III (Pell 1933). Another method for evaluating mandibular third molars is Winter’s classification, which is based on the angle formed by lines that intersect the long axes of the second and third molars (Winter 1926a).

Patients with partially impacted third molars may experience various symptoms, especially during episodes of pericoronitis. These symptoms can include fever, swollen lymph nodes, bad breath (halitosis), redness and swelling of the gums, and mild, low-grade pain that can escalate to severe or throbbing discomfort. These symptoms are often linked to innervation by the maxillary and mandibular branches of the trigeminal nerve, which can make it difficult for patients to accurately localize the source of pain (Benediktsdóttir et al. 2004).

Impaction of third molars is a recognized risk factor for oral conditions such as dental caries, pericoronitis and bone resorption (Yilmaz et al. 2016). Pericoronitis is a painful inflammatory condition that commonly affects individuals in their 20s and 30s. This condition can significantly impair a patient’s quality of life until the affected tooth is extracted. It is usually associated with impacted or partially erupted third molars, particularly in the lower jaw. Pericoronitis occurs due to inflammation of the pericoronal flap that covers these partially erupted teeth (Al-Anqudi et al. 2014; Shugars et al. 2006).

Caries is one of the most common pathological issues associated with impacted MTMs and the adjacent second molars. Caries on the distal surface of the mandibular second molars (MSMs) is often linked to an impacted MTM. This connection is primarily due to the MTM’s eruption pattern, which often leads to food impaction and makes it difficult to maintain proper oral hygiene in the area between the two molars (Alsaegh et al. 2022).

From a treatment perspective, performing restorative procedures, or root canal therapy, on the distal surface of the neighboring MSM can be significantly complicated by the presence of an impacted MTM. The close proximity of the MTM hinders access to the affected area, and this challenge is exacerbated by limited lighting and reduced visibility during treatment (Yadav et al. 2016).

Therefore, the study aimed to analyze the relationship between the position of the MTM and the occurrence of both pericoronitis and caries of the distal surface of the MSM, with the goal of identifying the patterns strongly associated with these conditions.

Materials and methods

Study design

This cross-sectional study was conducted from 2022 to 2024 and included 619 MTMs. These were examined in 365 patients at the Department of Oral Medicine, Faculty of Dental Medicine, Damascus University, Damascus, Syria, during routine dental examinations. Patients were included if they had at least one mandibular third molar. The study adhered to the STROBE guidelines for reporting observational studies (Von Elm et al. 2014), and complied with the ethical principles outlined in the Declaration of Helsinki (Goodyear et al. 2007). Ethical approval was obtained from the Damascus University Ethics Committee, and written informed consent was obtained from all participants prior to their inclusion in the study.

Sample size calculation

The required sample size was calculated using G*Power v3.1.9.2, following the methodology outlined by Alsaegh et al. (2022) To detect a statistically significant difference in proportions, a minimum of 600 MTMs was required, with a power of 85% and a significance level (α) of 0.05.

Patient population

A total of 365 patients were recruited from the Department of Oral Medicine, Faculty of Dental Medicine, Damascus University.

Inclusion criteria were Syrian nationality, age 18 or older, attendance at the Faculty of Dental Medicine, and providing consent to undergo a panoramic X-ray. Patients were included if at least one MTM was visible on the panoramic radiograph.

Exclusion criteria comprised incomplete patient records, non-Syrian nationality, poor-quality panoramic radiographs, patients under 18 years, and the absence of adjacent MSMs.

Radiographic examination

Digital panoramic radiographs were obtained with a MyRay Hyperion X9 at 5 mA and 76 kV, with an exposure time of 9.3 s. All radiographs were evaluated by a single trained examiner. The position of impacted molars was assessed using Winter’s Classification, based on the angulation of the impacted tooth relative to the long axis of the second molar. Impactions were categorized as mesioangular impaction (11° to 79°), horizontal impaction (80° to 100°), distoangular impaction (-11° to -79°), and vertical impaction (10° to -10°). Additionally, Pell and Gregory’s classification was partially applied to assess the depth of impaction only (Levels A–C) based on the position of the occlusal surface relative to the adjacent second molar, Level A indicates alignment with the occlusal plane, Level B indicates a position between the occlusal plane and the cementoenamel junction, and Level C indicates a position below the cementoenamel junction. The ramus relationship component (Class I–III) was not included in the present analysis.

Clinical examination

All participants underwent a clinical examination to assess for impacted MTMs and any associated symptoms such as swelling or pus discharge. Radiographic evaluation was also performed to determine the type of impaction, the presence of periodontal bone loss, and distal caries on adjacent mandibular second molars. The diagnosis of distal caries on adjacent MSMs was based on bitewing radiographs. Radiolucent lesions detected radiographically were confirmed clinically under direct vision using a dental mirror and caries explorer.

Data collection

Patient data were recorded according to the following variables: gender (male or female), age group (18–20 years, 21–25 years, and 26 years and older), and characteristics of mandibular third molar (MTM) impaction, including angulation according to Winter’s classification and depth according to the Pell and Gregory classification. Additionally, the presence of pericoronitis and dental caries was diagnosed based on clinical and radiographic examinations.

Data analysis

Data were analyzed using IBM SPSS Statistics version 24. Descriptive statistics were employed to summarize the demographic characteristics. The chi-square test was utilized to assess the associations between the variables and the characteristics of impacted mandibular third molars. A p-value of less than 0.05 was considered statistically significant.

Results

Descriptive analysis

A total of 619 MTMs were analyzed, including 418 from female participants and 201 from male participants. The most represented age group was 21–25 years, accounting for 40.8% of the sample, followed by individuals ≥ 26 years (33.2%), and those aged 18–20 years (26%). According to Winter’s classification, mesioangular impactions were the most prevalent and observed in 342 cases (55.3%). Based on Pell and Gregory’s classification, Class A impaction was identified in 396 MTMs (64%) (Table 1).

Table 1.

Distribution of MTM impaction according to gender, age, and classification

Variable	Category	Frequency(n)	Percentage (%)
Gender	Female	418	67.5%
	Male	201	32.5%
Age	18–20 Years	163	26%
	21–25 Years	265	40.8%
	More than 26 Years	188	33.2%
Winter’s classification	Mesioangular	342	55.3%
	Distoangular	8	1.8%
	Horizontal	67	32%
	Vertical	198	10.8%
	Buccally	4	0.6%
Pell and Gregory’s classification	Class A	396	64%
	Class B	95	15.3%
	Class C	128	20.7%

Pericoronitis

Pericoronitis was identified in 35 individuals. The highest prevalence was observed in the 21–25 age group, with a decline among individuals over the age of 26. Chi-square analysis demonstrated a statistically significant association between age and pericoronitis prevalence in MTMs (p = 0.020). Pericoronitis was observed more frequently in females than in males; however, this difference was not statistically significant (p = 0.543).

According to Winter’s classification, pericoronitis was found in 2.9% of mesioangular impactions, 10.1% of vertical impactions, and 7.4% of horizontal impactions, with no cases observed in distoangular impactions. There was a statistically significant association between impaction angulation and pericoronitis (p = 0.010). Vertical impaction showed a significantly higher risk of pericoronitis (OR = 2.83, 95% CI: 1.84–4.35, p = 0.010). Based on Pell and Gregory’s classification, pericoronitis was most frequently observed in Class A mandibular third molars, while Classes B and C showed similar prevalence rates. The differences among the three classes were statistically significant (p = 0.001). Class A impaction exhibited a strong association with pericoronitis (OR = 10.05, 95% CI: 2.39–42.5, p = 0.001) (Table 2).

Table 2.

Association of MTM impaction with pericoronitis according to gender, age, and classification

Variables	Category	Pericoronitis (yes) (n)(%)	Pericoronitis (No) (n)(%)	p-value
Gender	Female	22(62.9%)	396(67.8%)	0.543
	Male	13(37.1%)	188(32.2)
Age	18–20 Years	5(14.3%)	158(27.2%)	0.020*
	20–25 Years	23(65.7%)	224(41.7%)
	More than 26 Years	7(20%)	181(31.2%)
Winter’s classification	Mesioangular	10(28.6%)	332(56.8%)	0.010*
	Distoangular	0(0%)	8(1.4%)
	Vertical	20(57.1%)	178(30.5%)
	Horizontal	5(14.3%)	62(10.6%)
	Buccally	0(0%)	4(0.7%)
Pell and Gregory’s classification	Class A	33(94.3%)	363(62.2%)	0.001*
	Class B	1(2.9%) 9	4(16.1%)
	Class C	1(2.9%)	127(21.7%)

*p-value is significant at < 0.05

Distal caries on adjacent MSMs

Seventy-eight mandibular second molars adjacent to the examined MTMs presented with distal caries. A statistically significant relationship was found between age and caries prevalence (p = 0.000), with the highest incidence in patients over 26 years and a decreasing trend in younger groups.

The prevalence of caries was similar between males and females, with no statistically significant difference (p = 0.791). According to Winter’s classification, distal caries on MSMs were found in 12.2% of cases adjacent to mesioangular third molars, 14% adjacent to vertical impactions, and 16.4% adjacent to horizontal impactions. No cases of distal caries were observed adjacent to distoangular or buccal impactions. While mesioangular third molars had a slightly higher caries rate, differences between impaction types were not statistically significant (p = 0.618). Based on Pell and Gregory’s classification, the highest prevalence of distal caries was observed adjacent to Class A MTMs. Which showed a strong association with distal caries formation (OR = 12.6, 95% CI: 4.52–34.8, p < 0.001), whereas Classes B and C showed lower prevalence rates. (Table 3).

Table 3.

Association of MTM impaction with caries according to gender, age, and classification

Variables	Category	Caries Yes n(%)	Caries No n(%)	p-value
Gender	Female	47(60.3%)	371(68.6%)	0.142
	Male	31(39.7%)	170(31.4%)
Age	18–20 Years	7(9%)	56(29%)	0.000*
	21–25 Years	30(38.5%)	235(43.7%)
	More than 26 Years	41(52.6%)	147(27.3%)
Winter’s classification	Mesioangular	42(53.8%)	300(55.5%)	0.618
	Distoangular	0(0%)	8(1.4%)
	vertical	25(32.1%)	173(32%)
	Horizontal	11(14.1%)	56(10.4%)
	Buccally	0(0%)	4(0.7%)
Pell and Gregory’s classification	Class A	74(94.9%)	322(59.5%)	0.000*
	Class B	3(3.8%)	92(17%)
	Class C	1(1.3%)	127(23.5%)

*p-value is significant at < 0.05

Discussion

The removal of impacted teeth is among the most frequently performed procedures in oral and maxillofacial surgery for young adults. The patterns of third molar impaction can differ among various ethnic and racial groups (Zaman et al. 2021). Although the preventive extraction of MTMs remains a topic of active discussion due to potential complications, including nerve damage, views vary. Some research advises against the extraction of asymptomatic MTMs, while other studies advocate for conditional removal or early extraction (Ye et al. 2021).Comprehending the pattern of impaction and its associated pathological conditions can inform public health initiatives and influence decisions regarding the prophylactic removal of impacted MTMs (Zaman et al. 2021). To the best of our knowledge, this is the first study to investigate MTM impaction patterns, related carious lesions, and pericoronitis within the Syrian population. Recognizing impaction patterns is essential for planning anesthesia, estimating procedure duration and complexity, and anticipating potential surgical complications (Qadrie et al. 2025).

Regarding Pell and Gregory’s classification, Class A impaction was the most common type identified in this study, which aligns with several previous studies (Byahatti and Ingafou 2012; Jaroń and Trybek 2021; Kumar et al. 2017). The second most common MTM impact level found was level C, followed by level B. This indicates that the depth of impacted MTMs in our sample was generally shallower than that reported in Turkish (Yilmaz et al. 2016) and Malaysian populations (Mahdey et al. 2015), suggesting possible population-specific differences in eruption patterns.

It is important to note that age may have influenced this distribution, as younger patients (aged 14 to 18 years) may exhibit a higher proportion of deeper impactions that have not yet erupted. Determining the angulation of impacted MTMs relies on the angle formed between the impacted MTM and the neighboring MSM. The current study reveals that mesioangular impaction is the most prevalent type. According to Winter’s classification, mesioangular impaction occurs when the angle between the impacted MTM and the long axis of the adjacent MSM ranges from 11 to 79 degrees (Quek et al. 2003; Winter 1926b). During normal eruption, the MTM moves from a horizontal orientation to a mesioangular position and eventually becomes vertically aligned. Any disruption to this sequence may result in a mesioangular impaction. Additionally, research suggests that excessive mesial root growth may contribute to a distoangular impaction, whereas insufficient mesial root development may predispose the tooth to a mesioangular impaction (Quek et al. 2003). Numerous previous studies have also shown that mesioangular impaction is the most common type of impaction (Padhye et al. 2013; Jaroń and Trybek 2021; Prajapati et al. 2017). A higher proportion of impacted MTMs was observed in females (66.6%) than in males (33.4%) in this study. This finding was attributed to the earlier cessation of bone growth in females than in males, along with their smaller jaw and arch sizes (Idris et al. 2021). This finding contrasts with several previous studies reporting no significant gender-based differences (Padhye et al. 2013; Zaman et al. 2021). In this study, Winter’s classification shows that pericoronitis is significantly more common in vertically positioned third molars than in those angled toward the cheek. This is likely because the chewing surface of vertical molars presses against the overlying soft tissue, creating an area where food debris can accumulate and contribute to inflammation around the tooth crown (Nguyen et al. 2024). In this study, 57.1% of vertically impacted MTMs were linked to pericoronitis, emphasizing the significance of vertical impaction as a contributor to localized soft tissue inflammation.

Additionally, pericoronitis was identified in 5.7% of impaction cases. According to the Pell and Gregory classification, pericoronitis was most commonly associated with Class A molars, while the rates in Classes B and C are similar. Previous studies have also reported that most cases involve MTMs classified as Pell–Gregory Level A. These teeth positioned at or above the occlusal plane, making them more susceptible to irritation from opposing teeth and to the accumulation of food debris and plaque, which can lead to inflammation. The swelling and discomfort associated with pericoronitis are likely due to multiple factors, including an inflammatory response to bacterial biofilm and potential occlusal trauma from opposing teeth (Caymaz and Buhara 2021). In contrast, MTMs at class B are more deeply covered by bone and soft tissue, which reduces the likelihood of soft-tissue pocket formation and, consequently, the development of pericoronitis (Nguyen et al. 2024).

In the current study, distal caries was identified in 12.6% of impaction cases in MSMs. Previous research has reported similar rates of (12.2%) (Haddad et al. 2021) and (18.75%) (Kumar et al. 2017). Furthermore, the mesioangular impaction was linked to a higher occurrence of distal caries in the neighboring MSMs, followed by horizontal impaction, although not statistically significant. These results align with findings from earlier studies that reported similar outcomes (Kumar et al. 2017; Prajapati et al. 2017; Ozeç et al. 2009). Additionally, the caries was more common in class A impaction. These observations reaffirm previous findings (Prajapati et al. 2017). Factors such as limited cleaning space and inadequate oral hygiene may have contributed to these results. Moreover, this could be attributed to a poor contact point between the two teeth, which complicates daily oral hygiene. Given the relatively high rate of distal tooth decay in the adjacent MSM, it may be beneficial to prophylactically extract mesioangularly impacted MTMs, particularly if they are not fully embedded in the bone (Caymaz and Buhara 2021; Arandi and Jarrar 2025).

One limitation of this study is the inclusion of patients aged 18 and older. Since third molar eruption typically occurs between the ages of 18 and 25, the inclusion of younger individuals may not accurately reflect the true prevalence of distal caries and pericoronitis. Dental caries is a time-dependent process, and future studies should consider adopting a minimum age threshold of 25 years to provide a more accurate assessment. Moreover, this research is limited by its cross-sectional nature and the limited sample of Syrian patients who attended the Faculty of Dental Medicine at Damascus University. As a result, the majority of participants were already presenting with symptoms or dental conditions. To enhance the ability to generalize of the findings, future research should consider conducting community-based surveys with larger and more diverse populations or adopting a prospective study design.

Conclusion

Patterns of mandibular third molar impaction, especially vertical angulation and Class A depth, were significantly linked to an increased risk of pericoronitis and distal caries in neighboring second molars. In this research, mesioangular impaction, along with Class A depth, was the most common pattern, with a higher frequency among females. These results emphasize the clinical significance of impaction characteristics in anticipating potential clinical challenges and indicate that early detection and precautionary management of high-risk cases may contribute to a decrease in the occurrence of related pathologies.

Author contributions

[E.H]: Data Collection, Literature review, Writing – Original Draft. [S.K]: Methodology, Writing – Review & Editing. [M.H]: Supervision, Literature review.

Funding

Not applicable.

Data availability

The data that support the findings of this study are not openly available due to reasons of sensitivity and are available from the corresponding author upon reasonable request.

Declarations

Consent to publication

Informed consent to publication was obtained from participant.

Consent to participate

Informed consent to participate in this study was obtained from participant.

Competing interests

The authors declare no competing interests.