Prevalence of Pathologies Associated with Impacted Third Molars in Kosovar Population: an Orthopanthomography Study.

OBJECTIVE: The aim of this study was to evaluate the prevalence of pathologies associated with impacted third molars radiographically noticeable in a Kosovar population, as currently no data are available. METHODS AND MATERIALS: This was a retrospective study of 5515 panoramic images of patients who visited the University Dentistry Clinical Center of Kosovo. Of these 5515 patients, 2368 were males and 3147 were females. The age range was from 18 to 77 years. We reviewed panoramic images in order to determine the number of pathologies associated with impacted third molars. The following radiographic lesions were recorded: caries of impacted teeth and/or adjacent tooth, root resorption of adjacent tooth, periodontal bone loss of adjacent tooth of more than 5mm below the cemento-enamel junction and an increase in pericoronar gap over 4mm.
RESULTS: The prevalence of pathologies associated with impacted third molar in Kosovar population was 29.5%. Root resorption of adjacent tooth had the highest frequency of pathology 307 (23.7%). It was followed by periodontal bone loss of adjacent tooth of more than 5 mm 71 (5.5%) and caries 33 (2.5%). The lowest was an increase in pericoronar gap 15 (1.2%).
CONCLUSION: The most common pathology was root resorption, with the highest incidence of pathology localized in the maxilla 159 (32.3%). The prevalence of periodontal bone loss, caries and increase in pericoronar gap was significantly lower. The findings of our research could have an impact on development of prevention strategies that will proficiently deal with pathologies that result from impacted teeth.

Introduction

Third molars have the highest incidence of impaction in human dentition and their values have been on a rise (-).

As a result, the most frequent procedure in oral surgery worldwide is a removal of impacted third molars (, ). An impacted tooth, that is, the impacted third molar is a pathological condition in which tooth fails or is not excepted to erupt into the dental arch based on clinical and radiographic findings (). Failure of these teeth to erupt might be a consequence of late maturation of these teeth, an increased crown size, distal eruption of dentition lack of space, malposition or limited skeletal growth (, -).

An impacted maxillary and mandibular molar may take a variety of positions and levels of impaction, which can result with a range of pathologies associated with their impaction (, ). Most common pathologies associated with third molars are caries of impacted teeth or adjacent tooth, second molar tooth resorption, periodontal bone loss of adjacent tooth and odontogenic cysts (, ).

A great deal of discussion has been taking place worldwide about the suggestion for retaining or extraction of impacted third molar and it remains ongoing (, -). An extremely wide-ranged and balanced review of this topic has been published by Mercier and Precious (). In their article they emphasized that from 149 publications they have referred to, they concluded that for particular patient significant risks and benefits must be considered individually. Furthermore, oral surgeons are those who should act in the patient's best interests during the evaluation of the third molar extraction ().

In 1979, the National Institute for Dental Research, supported a conference dedicated to third molar, with main intention to reach an agreement about when should third molar extraction be advised and under what circumstances (). Since then guidelines for management of impacted third molars have been published (, ), the National Institute of Clinical Excellence () and the Scottish Intercollegiate Guidelines Network () have established the guidelines for removal of third molar, which were reviewed in 2005, and today they are foundations for ethical clinical practice. Considering the danger and cost (see Table 3) associated with third molar extractions, they concluded that there was no proper indication to support prophylactic removal of asymptomatic impacted third molars. On the other hand, the above mentioned guidelines did not consider recommendations by the American Association of Oral and Maxillofacial surgeons, supporting extraction of asymptomatic third molars considering that they are a potential cause of chronic inflammation, affecting patients to a range of periodontal and systemic problems in the future. The conclusions from the above mentioned studies were that extraction of third molars should only be carried out in the presence of pathology (-).

Table 3

Prevalence of pathologies associated with impacted third molars according to jaw

Table 3
Pathologies	Maxillan (%)	Mandibulan (%)	Totaln (%)
Caries of impacted and /or adjcaent teeth	32 (6.5)	1 (0.1)	33 (2.5) a
Periodontal bone lose of adjacent tooth of more than 5 mm	32 (6.5)	39 (4.9)	71 (5.5) b
Root resorbiton of adjcent tooth	159 (32.3)	148 (18.4)	307 (23.7) c
Inrease in pericoronar gap	15 (3.0)	0 (0.0)	15 (1.2) d
Total	493 (100)	804 (100)	1297 (100)
a Fisher's exact test, chi-square value = 47.42, df = 1, P < 0.001. 0 cells (0.0%) have expected count less than 5. The minimum expected count is 12.54.b Fisher's exact test is not significant.c Fisher's exact test, chi-square value = 31.66, df = 1, P < 0.001. 0 cells (0.0%) have expected count less than 5. The minimum expected count is 116.69.d Fisher's exact test, chi-square value = 22.16, df = 1, P < 0.001. 0 cells (0.0%) have expected count less than 5. The minimum expected count is 5.70.

Therefore, it is of utmost importance to be familiar with the prevalence of pathologies associated with impacted third molars ().

Despite the fact that until today there have been several studies concerning the potential development of pathologies associated with impacted third molars in populations from different countries (, -), the evidence is frequently inconsistent. Nitzan et al () report a prevalence of 8% of root resorption of second molar adjacent to impacted third molar. A long term study by Kahl B et al. (), where they evaluated tooth resorption on asymptomatic third molars in orthodontically treated patients, resulted with a prevalence of 8% resorption of upper second molar and 9.5% of lower second molar. However, Sewerin and von Wowern (), reported about the zero root resorption of adjacent second molar by impacted third molar.

Considering the fact that at present the frequency of pathologies associated with impacted third molars in Kosovar populations has not yet been evaluated, the aim of this study was to determine the prevalence of caries, periodontal bone loss of adjacent tooth and increase over 4mm in pericoronar space in Kosovar population visible on panoramic images.

Methods and Material

In this retrospective study, OPGs were obtained at the University Dentistry Clinical Center of Kosovo and analyzed for the pathologies associated with an impacted third molar. OPGs were taken as a standard procedure for all visiting patients. Consent forms of approval were signed by patients wherein they stated that their radiographs could only be used for educational and research purposes. The study protocol was approved by UDCCK and University of Zagreb School of Dental Medicine.

In this study, the inclusion criteria were as follows: OPGs of patients with minimum age of 18 years or older, males and females with all forms of impaction. OPGs with low quality were excluded from the study, including third molars with incomplete root formation. To collect patients’ data, their dates of birth and genders were used.

Panoramic radiographies were retrieved as digitalized images from the UCCK’s database. Images from the digital OPG machine were exported to JPEG format using the Sidexis Next generation imaging software, version 2.4®, integrated with the I-Max Touch Line:220-240V-7A 50/60Hz max exposure time: 15s, produced by Owandy (OWANDY 6, allée Kepler 77420 Champs-sur-Marne - FRANCE)®.

Third molar was defined as impacted with no functional occlusion, since it was not allowed to erupt on its eruption path by other tooth, soft tissue or bone and its roots were fully formed (). Primarily, impacted third maxillary and mandibular molars were identified in the OPG. Afterwards, the following radiographic lesions were recorded on OPG’s: caries in impacted teeth and adjacent tooth, periodontal bone loss on distal side of the second mandibular and maxillary molar, adjacent tooth root resorption and increased pericoronal space of dental follicle.

The norms for diagnosing pathologies associated with impacted third molar in maxilla or mandible were as follows: clear carious lesion noticed in OPG in the impacted third molar or in the adjacent second, The periodontal bone loss of the distal part of the second molar was measured from the cement-enamel junction to the marginal bone level over 5mm; Root resorption of adjacent tooth to impacted third molar on OPG, was a clear loss of substance in the root of second molar in maxilla and mandible due to direct contact between impacted third molar and adjacent tooth; Increase in the pericoronal space of the dental follicle over 4mm around third impacted molar.

For the measurement of the above mentioned dimensions we used ruler from the coral draw.

Statistical analysis

Data were analyzed using a Pearson chi-square test using the Statistical Package for the Social Sciences (version 18.0; SPSS, Inc, Chicago, IL). The age, gender, number of impacted third molars associated with pathologies was displayed by frequency and percentage. The relationships between the groups were analyzed using the Pearson chi-square test. The results were considered statistically significant if the p-value was less than 5% (p < 0.05).

All OPGs were assessed by a single examiner (ZS), a PhD candidate, to eliminate inter-examiner errors. The validity of the OPG readings was tested for 99 impacted third molars observed on 50 randomly selected OPGs using Kappa statistics ().

Two weeks after the first evaluation by the first author (ZS), the evaluation was repeated by the last author (FK). All OPGs were examined using a blind approach, without the possibility of evaluating age and gender. The average of the coefficients obtained for the relevant variables of this study was substantial (0.756).

Results

In our retrospective study, we screened the data of 5515 adult patients who were referred at the UCCK, of these 3147 (57.1%) were female and 2368 (42.9%) were male, with female participation in significantly higher percentage compared to men (p<0.001). From the included OPG’s, one or more impacted third molars were shown in 710 OPG-s: 414 (58.3%) in women and 296 (41.7%) in men; with gender ratio of 1:1.4 {Table 1}.

Table 1

Distribution of patients with impacted third molars according to age group

Table 1
Age groups	Malen (%)	Femalen (%)	Totaln (%)
18-20	73 (24.7)	122 (29.5)	195 (27.5)
21-30	106 (35.8)	194 (46.9)	300 (42.3)
31-40	43 (14.5)	48 (11.6)	91 (12.8)
41-50	33 (11.1)	23 (5.6)	56 (7.9)
51-60	23 (7.8)	21 (5.1)	44 (6.2)
61-77	18 (6.1)	6 (1.4)	24 (3.4)
Total	296 (100)	414 (100)	710 (100)
Pearson Chi-Square value = 27.42, df = 5, P < 0.001. 0 cells (0.0%) have expected count less than 5. The minimum expected count is 10.01.

The age range was from 18 to 77 years (mean age ± SD = 29.3 ± 12.8). Men were older than women: mean age ± SD = 32.1 ± 14.6 respectively 27.2 ± 10.9, p <0.001). Six working age groups were included in this research: 18-20, 21-30, 31-40, 41-50, 51-60 and greater than 60 {Table 1}. Pathologies associated with impacted teeth dominated in younger age groups, with their prevalence around 70% (preciously 27.5 + 42.3 = 69.8%) {Table 1}.

Table 2 presents a total number of 1297 impacted third molars that were found in both jaws.

Table 2

Prevalence of pathologies associated with impacted third molars according to age groups

Table 2
Pathologies	18-20n (%)	21-30n (%)	31-40n (%)	41-50n (%)	51-60n (%)	61-77n (%)	Total,n (%)
Caries of impacted and /or adjcaent teeth	6 (1.5)	25 (4.3)	0 (0.0)	2 (2.4)	0 (0.0)	0 (0.0)	33 (2.5)
Periodontal bone lose of adjacent tooth of more than 5 mm	43 (10.9)	24 (4.2)	2 (1.4)	1 (1.2)	1 (1.6)	0 (0.0)	71 (5.5)
Root resorbiton of adjcent tooth a	85 (21.5)	133 (23.0)	48 (33.8)	25 (30.1)	10 (16.4)	6 (16.2)	307 (23.7)
Inrease in pericoronar gap	6 (1.5)	4 (0.7)	1 (0.7)	1 (1.2)	3 (4.9)	0 (0.0)	15 (1.2)
Total	396 (100)	578 (100)	142 (100)	83 (100)	61 (100)	37 (100)	1297 (100)
a Pearson Chi-Square value = 14.11, df = 5, P = 0.015. 0 cells (0.0%) have expected count less than 5. The minimum expected count is 8.76.

Detectable radiographic lesions were seen in 383 impacted third molars. A significantly higher frequency of pathologies associated with those impactions were found significantly more in the maxilla compared to the mandible (26.2%, P<0.001). {Table3}. In maxilla 42.6% (36.9 + 5.7) of third impacted molar had one or two pathologies, whereas the prevalence of pathologies in third impacted molars was 21.5% (19.6 + 1.9){Table 4}.in mandible

Table 4

Prevalence of pathologies associated with impacted teeth according to jaw

Table 4
Pathologies	Maxillan (%)	Mndibulan (%)	Totaln (%)
0	283 (57.4)	631 (78.5)	914 (70.5)
1	182 (36.9)	158 (19.6)	340 (26.2)
2	28 (5.7)	15 (1.9)	43 (3.3)
Total	493 (100)	804 (100)	1297 (100)
Pearson Chi-Square value = 67.43, df = 2, P < 0.001. 0 cells (0.0%) have expected count less than 5. The minimum expected count is 16.34.

The prevalence of root resorption was the most frequent pathological condition with a prevalence of 23.7% in our studied teeth. It was followed by over 5mm periodontal bone loss of the distal part of the second molar 5.5% and caries appearing in 2.5% cases. An increase in pericoronal space of the dental follicle over 4mm around third impacted molar had the lowest prevalence of only 1.2% in an impacted third molar between the maxilla and mandible {Table 3}.

Table 5 shows there were no statistically significant differences in the prevalence of pathologies between male and female patients. The rates of pathological lesions observed in between left and right side had an equal prevalence of: 29.7% (26.4 + 3.3) right and 29.4% (26.1 + 3.3) left side {Table 6 and 7}.

Table 5

Prevalence of pathologies associated with impacted third molars according to sex

Table 5
Pathologies	Malen (%)	Femalen (%)	Totaln (%)
Caries of impacted and /or adjcaent teeth	8 (1.5)	25 (3.2)	33 (2.5) a
Periodontal bone lose of adjacent tooth of more than 5 mm	25 (4.8)	46 (5.9)	71 (5.5) b
Root resorbiton of adjcent tooth	121 (23.3)	186 (23.9)	307 (23.7) c
Inreas in pericoronar gap	6 (1.2)	9 (1.2)	15 (1.2) d
Total	520 (100)	777 (100)	1297 (100)
a, b, c, d Fisher's exact test is not significant.

Table 6

Prevalence of number of pathologies associated with impacted third molar according to side in OPG's

Table 6
Pathologies	Rightn (%)	Leftn (%)	Totaln (%)
0	421 (70.3)	493 (70.6)	914 (70.5)
1	158 (26.4)	182 (26.1)	340 (26.2)
2	20 (3.3)	23 (3.3)	43 (3.3)
Total	599 (100)	698 (100)	1297 (100)
Pearson Chi-Square value = 0.02, df = 2, P = 0.991. 0 cells (0.0%) have expected count less than 5. The minimum expected count is 19.86.

Table 7

Prevalence of pathologies associated with impacted third molars according to side of jaws

Table 7
Pathologies	Right siden (%)	Left siden (%)	Totaln (%)
Caries of impacted and /or adjcaent teeth	14 (2.3)	19 (2.7)	33 (2.5) a
Periodontal bone lose of adjacent tooth of more than 5 mm	31 (5.2)	40 (5.7)	71 (5.5) b
Root resorbiton of adjcent tooth	150 (25.0)	157 (22.5)	307 (23.7) c
Inreas in pericoronar gap	3 (0.5)	12 (1.7)	15 (1.2) d
Total	599 (100)	698 (100)	1297 (100)
a, b, c, d Fisher's exact test is not significant.

After evaluating the entire results, it could be noticed that in 1297 impacted teeth found in 710 OPG’s, 70.5% of those impacted third molars were not influenced by any of the four pathologies. On the other hand, 26.2% of the cases were influenced by at least one pathological lesion and 3.3% of cases by two pathological lesions.

Discussion

Currently dental practitioners and oral surgeons face challenges to determine a constant guiding principle regarding the extraction of asymptomatic third molar impaction (, , ).

However, according to a compromise conference held for removal of third molar impaction there is almost no controversy concerning the removal of impacted third molars when pathologies are associated with them (, ). They defined criteria for impacted third molar removal, indicating that surgery should be carried out as soon as possible once the diagnose is made for a non-restorable caries of adjacent or impacted teeth, resorption of adjacent teeth, bone destruction, follicle disease and infections (, ). Nevertheless, it is also significantly important to highlight the fact that the Scottish Intercollegiate Guideline Network has rejected a prophylactic extraction of asymptomatic impacted third molars (). This extraction rejection may be a result of deficient evidence supporting prophylactic extraction of these teeth ().

Bearing in mind the significant importance of having data on the incidence of pathologies associated with the impacted third molar, the main focus of our study was its epidemiology and prevalence in a Kosovar population.

To determine the prevalence of pathologies associated with an impacted third molar is challenging due to the difficulties that emerge due to the fact that a random sample from the general population is required. Obtaining such samples is admittedly complex because of the arguable ethical considerations and associated costs (, ). In order to avoid such a bias, our target was to evaluate the OPGs of the patients that have already been taken at the UDCCK.

The prevalence of pathologies in our study is shown in Table 3. From the literature, it has been reported that the impactions of the third molars have been causing root resorption of adjacent second molars (, ). Our evaluation of the tooth resorption between maxilla and mandible showed the prevalence of 23.7%. Our finding shows a much higher prevalence of root resorption compared to the findings of similar studies of a Honk Kong Chinese population by Chu et al () who reported a total figure of only 13 (0.4%) cases of resorption amongst over 3000 impacted third molars. Also, it is different from the findings by van Der Linden et all who reported a prevalence of only 0.9% in 2872 impacted third molars (). On the contrary, the finding by Ahlqwist et al (), in a study of 121 impacted third molars, reported only one case of second molar resorption, whereas Sewerin and von Wowern reported about a zero second molar impaction ().

The variation of tooth resorption prevalence can be explained by diverse definitions of root resorption in different studies. In this study, root resorption was defined as a clear loss of the tooth substance, while a group of researches () defined root resorption as an irregularity and discontinuity of the root surface. Furthermore, Stanley et al have emphasized that it is complicated to determine radiologically if coronal radiolucency of second molar adjacent to third molar is due to caries or root resorption ().

The periodontal bone loss of the distal part of the second molar more than 5mm below the cemento-enamel junction in our study group was (5.5%) and this was second largest pathology associated with impacted third molars. On the other hand, it was the highest score of pathology reported in data by Chu et al. They reported about the prevalence of approximately 9% of periodontal bone loss of more than 5 mm in second mandibular molar adjacent to impacted third molar in 3778 impacted third molars (). Wynand van der Linden et al (), obtained a similar finding to our study of periodontal bone loss of 4.9%, pathology which was mostly located in mandible. In our study, the maxilla had significantly higher prevalence of periodontal bone loss with 32.2%, compared to the mandible with only 18.4%. In their study, Mercurie and Presier stated that it is challenging to compare periodontal bone loss due to the use of dissimilar definitions about the same condition (). In our study, we have found that in 1238 impacted teeth, caries occurred only in 2.5% of the teeth studied. Caries not being dominating pathology in our study, is dissimilar to retrospective finding in a study of 1001 OPG’s of patients that visited dental school () The percentage of caries in impacted third molars or adjacent molars was 7.1% and 42.7%, respectively. In general, their finding was consistent with other studies (, ). Nevertheless, caries figures found in our study might be underrated because the diagnosis of caries was based only on OPG’s.

In previous radiographically based studies researching increased coronal radiolucency surrounding impacted third molar over 4 mm reported the frequency of no more than 1% (, ). In our study, we observed coronal radiolucency of (1.2%) with its higher percentage located in mandible. However, in studies when a space of >3mm for widened coronal radiolucency was used, the prevalence of the pathology for both jaws was up to 4.6% (). Assessing the coronal radiolucency changes, Stephens emphasized the importance of attentiveness in order to avoid confusing a follicular space enlargement with a developing dentigerous cyst (). He believed that inaccuracy appears when follicular space >2.5mm in radiographic examinations is classified as cyst.

On the other hand, follicular tissues of radiologically normal teeth when examined histologically showed that in 34% to 46.5% of cases (, , ) had histological findings pinpointing of dentigerous cyst formation. Therefore, radiographic appearance may not be an exceptionally dependable indicator of the absence of disease within the dental follicle.

Study Limitations: Study samples were taken only from the University Clinical Center of Kosovo. This clinical center is the main health, education, and research institution for dentistry in Kosovo. The sample size represents 0.44% of the population. However, the sample of the patients with impacted third molars featured a slight dominance of females over males, which may have been a consequence of female patients having higher awareness regarding their oral health.

Conclusion

Evaluating the prevalence of pathologies associated with impacted third molar in a certain population contributes to making a comparison pattern in different regions and populations worldwide.

Our data in Kosovar population show that the prevalence of pathologies is 29.5% with a distinct predilection of pathologies in impacted third maxillary molars. The most common pathology appeared to be root resorption of adjacent tooth, followed by periodontal bone loss, caries and increased pericoronal radiolucency.

An early detection and data about the prevalence of pathologies associated with impacted third molar is essential in order to accomplish an effective treatment. Despite the fact that the prevalence of associated pathologies is considerably low in our study, it is of utmost importance to carry out regular examinations in order to keep the asymptomatic impacted third molars in good oral health.

Further studies are highly recommended and needed in Kosovo and the region.