Depth and proximity of third molars to the inferior alveolar canal in panoramic radiographs of a Latin American population*

Profundidad y proximidad de terceros molares al canal alveolar inferior en radiografías panorámicas de una población latinoamericana

María Claudia Garcés-Elías[1][*]

Roberto A. León-Manco[2]

Jorge A. Beltrán[3]

[1] Master of Business Administration (MBA). Academic Department of Social Dentistry, Facultad de Estomatología, Universidad Peruana Cayetano Heredia, Lima, Perú. https://orcid.org/0000-0003-4873-7661

[2] MPH, Professor, Academic Department of Social Dentistry, Facultad de Estomatología, Universidad Peruana Cayetano Heredia, Lima, Perú. https://orcid.org/0000-0001-9641-1047

[3] PhD. Estomatology. Academic Department of Medicine and Bucomaxillofacial surgery, Facultad de Estomatología, Universidad Peruana Cayetano Heredia, Lima, Perú. https://orcid.org/0000-0001-9910-0930

Author notes:

Correspondence to: [*] Corresponding autor: María Claudia Garcés-Elías, maria.garces@upch.pe

Conflicts of interest:

Conflicts of interest: The authors state that they have no conflict of interest.

Date received: 03/1/2023

Date accepted: 29/8/2023

ABSTRACT

Introduction:

extraction of lower third molars involve the possible occurrence of complications such as injury of the content of the Inferior Alveolar Canal.

Methods:

a cross-sectional study was conducted with a sample of 6488 lower molar records of digital panoramic radiographs of patients from 6 Latin American countries from 2010-2015. The variables studied were the depth of lower third molar according to the Pell and Gregory classification, and the proximity of a third molar to the Inferior Alveolar Canal that was evaluated according to the proposed classification, based on a modification of the Langlais et al classification.20 Descriptive and bivariate statistical analyses were performed.

Results:

in terms of the proximity, the highest frequency was Intact with 27.45%(n=1781). Regarding the depth of the lower third molar, the most frequent were the Position B with 46.90%(n=3043) and Position A with 46.75%(n=3033). The proximity and depth of the lower third molar had statistical difference according to age(p<0.01) and sex (p<0.001). The overall proximity of the lower third molar to the Inferior alveolar canal, according to depth was 37.52%(n=1766) in Position A, in Position B it was 54.51%(n=2566) and Position C was 7.97%(n=375) and had association between variables(p<0.001).

Conclusions:

taking into consideration the modified classification of Langlais et al.20, lower third molars are close to the Inferior Alveolar Canal, and according to the Pell and Gregory classification for the depth, the most frequent positions are A and B. In addition, proximity and depth were associated with each other, and with the co-variables country, age, and sex.

Keywords:

radiography panoramic, molar third, mandible, adult

Resumen

Introducción:

la extracción de terceros molars inferiores implica la posible aparición de complicaciones, como la lesión del contenido del Canal Alveolar Inferior.

Métodos:

se realizó un estudio transversal con una muestra de 6488 registros de terceros molares inferiores de radiografías panorámicas digitales en pacientes de 6 países latinoamericanos, entre 2010-2015. Las variables fueron profundidad del tercer molar inferior según la clasificación de Pell y Gregory, y proximidad del tercer molar al Canal Alveolar Inferior, evaluada según una clasificación propuesta, basada en la clasificación modificada de Langlais et al.20 Se realizaron análisis estadísticos descriptivos y bivariados.

Resultados:

en la proximidad, la mayor frecuencia se presentó en Intacto con 27,45%(n=1781); en cuanto a la profundidad del tercer molar inferior, las más frecuentes fueron la Posición B con 46,90%(n=3043) y la Posición A con 46,75%(n=3033). La proximidad y profundidad del tercer molar inferior presentaron diferencias estadísticas de acuerdo con la edad (p<0,01) y sexo (p<0,001). La proximidad total del tercer molar inferior al canal alveolar inferior, según la profundidad fue de 37,52%(n=1766) en Posición A, en Posición B de 54,51%(n=2566) y Posición C de 7,97%(n=375). Además, se presentó asociación entre las variables (p<0,001).

Conclusiones:

considerando la clasificación modificada de Langlais et al.20, la mayoría de los terceros molares inferiores están próximos al canal alveolar inferior; y según la profundidad de Pell y Gregory, las posiciones más frecuentes son A y B. Además, la proximidad y la profundidad se asociaron entre sí, y con las co-variables país, edad y sexo.

Palabras clave:

radiografía panorámica, tercer molar, mandíbula, adulto

INTRODUCTION

Third molars, with an average appearance of around 20 years of age1,2, usually face obstacles for an adequate eruption, representing 98% of the impactions, located mostly at the mandibular level3,4. There are also preponderant factors in the eruption pattern such as limited skeletal growth, distal eruption, verticalization in the growth of the condyle, the increase in the size of the dental crowns, and the delayed maturation of the third molars5. However, the eruption and possible impaction of these teeth is mostly linked to the space availability at the posterior ends of the dental arch6. Additionally, they can be linked to certain pathological conditions such as dental caries, periodontitis, pericoronaritis, external root resorption of the adjacent tooth, and the possible development of infections or cysts, among others7,8.

On the other hand, the extraction of third molars is considered one of the most frequent surgical procedures in oral surgery, even though it involves the possible occurrence of intra and post-operative complications9. One of them is the injury to the vascular-nerve bundle contained in the Inferior Alveolar Canal (IAC), caused by direct or indirect trauma10,11, with a prevalence of 0.4 to 8.4%12,13 that can have a significant impact on the quality of life of patients due to the damage caused to speech, chewing, etc14,15. However, these scenarios can be avoided with an accurate diagnostic imaging prior to the procedure, highlighting the importance of the panoramic radiography as a useful tool to evaluate the potential risk caused by the IAC, based on its proximity to the third molars due to the wide visualization it provides of the mandibular structures, condyles and possible nearby pathologies16. Despite the above, one of the disadvantages of the panoramic radiography is that it provides information only in two dimensions, so the absence of the cortical bone of the mandibular canal may not be evident with two-dimensional methods, and it would be complex to determine whether its direction is buccal or lingual to the roots. Consequently, it brings the attention to the presence of more accurate alternatives such as the Cone Beam Computed Tomography (CBCT), which is accepted for its high sensitivity in predicting exposure of the neurovascular bundle. CBCT is an effective method to locate the canal and its relationship with the roots of the lower third molars since it can generate images through the mandibular body in different planes. However, it should be mentioned that due to its high cost and limited availability, CBCT is not usually the radiographic technique of first choice for a pre-surgical evaluation of lower third molars in contrast to the panoramic radiography17. Additionally, thanks to digitalization, panoramic radiographs are an alternative that takes less time, reduces the radiation dose, and offers the possibility of improving the image by means of the computer18.

It is important to mention that there are several? classifications to evaluate the anatomical location of the third molars. The Pell and Gregory classification is based on the relationship between the level of this dental piece and the occlusal plane of the contiguous second molar. Therefore, it allows determining its relative depth as well as the relation it has with the ascending branch and the distal surface of the second molar19.On the other hand, the classification of Langlais et al. uses the IAC and its proximity to the roots of third molars as a reference point and it defines the presence of three types of images based on this relationship: dark band phenomenon, constriction of the diameter of the IAC, and discontinuity of the IAC20. However, due to the great variability observed in function to the IAC, it allowed the researchers of the academic section of Buccomaxillofacial Imaging of the Faculty of Stomatology at Universidad Peruana Cayetano Heredia, to postulate a modification of the mentioned classification, where besides appreciating the already known variants independently, two more signs were added: intact and change of direction of the IAC. It is important to mention that the latter is highly frequent in radiographic findings21.

The evidence refers to multiple investigations related to third molars and their complications; however, there are few studies about their location, especially in Latin America15,22. Therefore, the objective of this research was to determine the depth and proximity to IAC of third molars in panoramic radiographs of Latin American population.

METHODS

The present investigation was a cross-sectional study, with a sample, selected by convenience, and composed of a database of 6488 records of lower molars from digital panoramic radiographs, from patients between 18 and 65 years of age and of both sexes. This database belongs to the records of thesis research, carried out by 11 students of the second Professional Specialty international program in Oral and Maxillofacial Radiology of the Universidad Peruana Cayetano Heredia, from Bolivia (La Paz), Colombia (Bogotá and Nariño), Costa Rica (Guanacaste), Ecuador (Cuenca, Loja, Macas and Tungurahua), Mexico (State of Mexico) and Peru (Ayacucho and Lima), within the period 2010 to 2015.

The students of the specialization program collected the information after an inter-examiner calibration process, having as a gold standard a professor specialized in oral and maxillofacial radiology with more than 20 years of experience, obtaining as a result a Kappa Index greater than 0.80 in all cases. The variables of the study were the depth of the lower third molar according to the classification of Pell and Gregory19 (figure 1), whose categories consisted of Position A when the highest point of the lower third molar is at or above the occlusal surface of the second molar, Position B when the highest point of the lower third molar is below the occlusal line but above the cervical line of the second molar, and Position C when the highest point of the lower third molar is at or below the cervical line of the second molar.

Figure 1

Aranda L.32 A. The highest point of the included tooth is at or above, the occlusal surface of the second molar. B. The highest point of the tooth is below the occlusal line, but above the cervical line of the second molar. C. The highest point of the tooth is, at or below, the cervical line of the second molar.

0121-246X-rfoua-35-02-52-gf1.png

Fuente: por los autores

The proximity of the third molar to IAC was evaluated according to the proposed classification in this study that is based on a modification of Langlais et al’s classification20 (Figure 2). This establishes the following categories: Intact, when the roots of the third molar show no signs of proximity to the IAC; dark band phenomenon, when a radiolucent band is observed crossing the roots of the third molars; change of direction of the IAC, when it describes a marked curve close to the apical zone of the roots of the third molars; discontinuity of the IAC, when it is interrupted or non-existent when it crosses the roots of the third molars; constriction of the diameter of the IAC, when there is a decrease in its diameter that crosses the roots of the third molars; additionally, it is contemplated to include their different combinations. Furthermore, the variable was dichotomized into Intact and Proximal (in the latter, all other categories were grouped). Likewise, factors such as country, age, sex, and molar were considered as descriptive co-variables. With the database cleaned, the descriptive and bivariate analyses were performed; the tests used were Chi-square and Chi-square of linear trend for the associations of qualitative variables. For the mean differences, the Mann Whitney U and Kruskal Wallis tests were used, due to the absence of normality presented by the age variable, the Kolmogorov-Smirnov test was used. The analysis was developed in the STATA 17.0 program. Lastly, a confidence level of 95% and a p<0.05 was used.

Figure 2

Aranda L.32 A. Intact: The roots of the third molar do not show signs of proximity to the IAC. B. Dark band phenomenom: we observe a radiolucent band that crosses the roots of the third molars. C. Constriction of the diameter of the IAC. There is a decrease in the diameter of the IAC that crosses the roots of the third molar. D. IAC discontinuity: the IAC is interrupted or non-existent when it crosses the roots of the third molar. E. Change of direction of the IAC: the IAC describes a marked curve close to the apical zone to the roots of the third molars.

0121-246X-rfoua-35-02-52-gf2.png

Fuente: por los autores

All the information collected, since it originated from research thesis, was approved by the Institutional Ethics Committee of the Universidad Peruana Cayetano Heredia with SIDISI registration No. 63901.

RESULTS

Regarding the proximity of the lower third molar to the IAC, according to the modified Langlais et al. classification, the highest frequency was Intact with 27.45% (n=1781), followed by Dark Band Phenomenon with 14.90% (n=967) and Dark Band Phenomenon + IAC Discontinuity with 12.87% (n=835). Regarding the depth of the third lower molar and according to Pell and Gregory, the most frequent were Position B with 46.90% (n=3043) and Position A with 46.75% (n=3033) and the least frequent was Position C with 6.35% (n=412). According to country, in the intact category, Peru had the highest frequency with 28.92% (n=515) and Costa Rica had the lowest frequency with 5.50% (n=124). Additionally, the variable country was associated with all variables (p<0.001) (Table 1). Likewise, the proximity and depth of the lower third molar were statistically different according to age (p<0.01) and sex (p<0.001) (Table 2). The overall proximity of the lower third molar to the IAC according to depth was 37.52% (n=1766) in Position A, in Position B it was 54.51% (n=2566) and Position C was 7.97% (n=375) and had an association between the variables (p<0.001) (Table 3).

Table 1

Frequency of the location of lower third molars according to countries in panoramic radiographs of Latin American population

Variables n % Country
Bolivia Colombia Costa Rica Ecuador México Perú p
n % n % n % n % n % n %
Proximity of the lower third molar to the IAC (Modified Langlais et al.20 classification)
Intact 1781 27.45 339 19.03 225 12.63 98 5.50 474 26.61 130 7.30 515 28.92 <0.001**
Proximal 4707 72.55 395 8.39 800 17.00 210 4.46 1168 24.81 1036 22.01 1098 23.33
Intact 1781 27.45 339 19.03 225 12.63 98 5.50 474 26.61 130 7.30 515 28.92 <0.001*
Dark band phenomenom 967 14.90 2 0.21 148 15.31 39 4.03 255 26.37 191 19.75 332 34.33
Change of IAC address 35 0.54 4 11.43 10 28.57 2 5.71 11 31.43 1 2.86 7 20.00
Discontinuity of IAC 877 13.52 28 3.19 152 17.33 39 4.45 203 23.15 2 0.23 453 51.65
Constriction of the IAC diameter 237 3.65 10 4.22 32 13.50 14 5.91 166 70.04 1 0.42 14 5.91
Dark band phenomenom + Change of IAC address 89 1.37 2 2.25 16 17.98 1 1.12 33 37.08 2 2.25 35 39.33
Dark band phenomenom + Discontinuity of IAC 835 12.87 133 15.93 144 17.25 41 4.91 132 15.81 261 31.26 124 14.85
Dark band phenomenom + Constriction of the IAC diameter 147 2.27 16 10.88 25 17.01 5 3.40 44 29.93 46 31.29 11 7.48
Change of IAC address + Discontinuity of IAC 89 1.37 19 21.35 17 19.10 3 3.37 14 15.73 0 0.00 36 40.45
Change of IAC address + Constriction of the IAC diameter 99 1.53 34 34.34 18 18.18 1 1.01 40 40.40 0 0.00 6 6.06
Discontinuity of IAC + Constriction of the IAC diameter 302 4.65 64 21.19 49 16.23 31 10.26 135 44.70 6 1.99 17 5.63
Dark band phenomenom + Change of IAC address + Discontinuity of IAC 106 1.63 22 20.75 38 35.85 5 4.72 11 10.38 12 11.32 18 16.98
Dark band phenomenom + Change of IAC address + Constriction of the IAC diameter 48 0.74 8 16.67 15 31.25 1 2.08 7 14.58 10 20.83 7 14.58
Dark band phenomenom + Discontinuity of IAC + Constriction of the IAC diameter 535 8.25 37 6.92 71 13.27 14 2.62 49 9.16 355 66.36 9 1.68
Change of IAC address + Discontinuity of IAC + Constriction of the IAC diameter 117 1.80 13 11.11 28 23.93 8 6.84 43 36.75 3 2.56 22 18.80
Dark band phenomenom + Change of IAC address + Discontinuity of IAC + Constriction of the IAC diameter 224 3.45 3 1.34 37 16.52 6 2.68 25 11.16 146 65.18 7 3.13
Depth of lower third molar (Pell and Gregory(19))
Position A 3033 46.75 412 13.58 397 13.09 172 5.67 737 24.30 490 16.16 825 27.20 <0.001**
Position B 3043 46.90 258 8.48 514 16.89 124 4.07 744 24.45 657 21.59 746 24.52
Position C 412 6.35 64 15.53 114 27.67 12 2.91 161 39.08 19 4.61 42 10.19
Total 6488 100.00 734 11.31 1025 15.80 308 4.75 1642 25.31 1166 17.97 1613 24.86

[i]*Chi-square linear trend test

[ii]**Chi-square test

[iii]Source: by the authors

Table 2

Frequency of location of lower third molars according to age, sex and molar in panoramic radiographs of Latin American population

Location n % Age Sex Molar
X SD p Male Female p Left Right p
n % n % n % n %
Proximity of the lower third molar to the IAC (Modified Langlais et al.20)
Intact 1781 27.45 29.56 9.29 <0.001** 889 49.92 892 50.08 <0.001*** 909 51.04 872 48.96 0.177***
Proximal 4707 72.55 26.53 7.02 1878 39.90 2829 60.10 2314 49.16 2393 50.84
Intact 1781 27.45 29.56 9.29 <0.001* 889 49.92 892 50.08 <0.001*** 909 51.04 872 48.96 0.052***
Dark band phenomenom 967 14.90 27.58 7.46 366 37.85 601 62.15 491 50.78 476 49.22
Change of IAC address 35 0.54 26.51 5.27 17 48.57 18 51.43 20 57.14 15 42.86
Discontinuity of IAC 877 13.52 27.12 7.21 407 46.41 470 53.59 414 47.21 463 52.79
Constriction of the IAC diameter 237 3.65 26.59 6.62 91 38.40 146 61.60 111 46.84 126 53.16
Dark band phenomenom + Change of IAC address 89 1.37 27.24 7.76 26 29.21 63 70.79 47 52.81 42 47.19
Dark band phenomenom + Discontinuity of IAC 835 12.87 26.05 7.36 349 41.80 486 58.20 428 51.26 407 48.74
Dark band phenomenom + Constriction of the IAC diameter 147 2.27 26.25 6.52 66 44.90 81 55.10 70 47.62 77 52.38
Change of IAC address + Discontinuity of IAC 89 1.37 25.63 5.75 25 28.09 64 71.91 55 61.80 34 38.20
Change of IAC address + Constriction of the IAC diameter 99 1.53 25.29 5.72 36 36.36 63 63.64 44 44.44 55 55.56
Discontinuity of IAC + Constriction of the IAC diameter 302 4.65 25.83 6.16 134 44.37 168 55.63 143 47.35 159 52.65
Dark band phenomenom + Change of IAC address + Discontinuity of IAC 106 1.63 24.84 5.49 40 37.74 66 62.26 44 41.51 62 58.49
Dark band phenomenom + Change of IAC address + Constriction of the IAC diameter 48 0.74 27.94 7.36 8 16.67 40 83.33 19 39.58 29 60.42
Dark band phenomenom + Discontinuity of IAC + Constriction of the IAC diameter 535 8.25 25.36 6.56 202 37.76 333 62.24 278 51.96 257 48.04
Change of IAC address + Discontinuity of IAC + Constriction of the IAC diameter 117 1.80 26.91 6.59 38 32.48 79 67.52 48 41.03 69 58.97
Dark band phenomenom + Change of IAC address + Discontinuity of IAC + Constriction of the IAC diameter 224 3.45 26.34 6.79 73 32.59 151 67.41 102 45.54 122 54.46
Depth of lower third molar (Pell and Gregory19)
Position A 3033 46.75 28.59 8.67 <0.001* 1334 43.98 1699 56.02 0.008*** 1538 50.71 1495 49.29 0.172***
Position B 3043 46.90 26.06 6.66 1240 40.75 1803 59.25 1494 49.10 1549 50.90
Position C 412 6.35 27.92 7.74 193 46.84 219 53.16 191 46.36 221 53.64
Total 6488 100.00 27.36 7.83   2767 42.65 3721 57.35   3265 50.32 3223 49.68  

[i]*Kruskal Wallis Test

[ii]**Mann Whitney U Test

[iii]*** Chi-square test

[iv]Source: by the authors

Table 3

Proximity of the location of the lower third molars according to depth in panoramic radiographs of the Latin American population

Location n % Depth of lower third molar (Pell and Gregory19
Position A Position B Position C p
n % n % n %
Proximity of the lower third molar to the IAC (modified Langlais et al.20)
Intact 1781 27.45 1267 71.14 477 26.78 37 2.08 <0.001**
Proximal 4707 72.55 1766 37.52 2566 54.51 375 7.97
Intact 1781 27.45 1267 71.14 477 26.78 37 2.08 <0.001*
Dark band phenomenom 967 14.90 427 44.16 469 48.50 71 7.34
Change of IAC address 35 0.54 7 20.00 24 68.57 4 11.43
Discontinuity of IAC 877 13.52 395 45.04 450 51.31 32 3.65
Constriction of the IAC diameter 237 3.65 98 41.35 120 50.63 19 8.02
Dark band phenomenom + Change of IAC address 89 1.37 15 16.85 58 65.17 16 17.98
Dark band phenomenom + Discontinuity of IAC 835 12.87 344 41.20 435 52.10 56 6.71
Dark band phenomenom + Constriction of the IAC diameter 147 2.27 46 31.29 88 59.86 13 8.84
Change of IAC address + Discontinuity of IAC 89 1.37 30 33.71 53 59.55 6 6.74
Change of IAC address + Constriction of the IAC diameter 99 1.53 36 36.36 46 46.46 17 17.17
Discontinuity of IAC + Constriction of the IAC diameter 302 4.65 105 34.77 156 51.66 41 13.58
Dark band phenomenom + Change of IAC address + Discontinuity of IADC 106 1.63 26 24.53 69 65.09 11 10.38
Dark band phenomenom + Change of IAC address + Constriction of the IAC diameter 48 0.74 8 16.67 28 58.33 12 25.00
Dark band phenomenom + Discontinuity of IAC + Constriction of the IAC diameter 535 8.25 165 30.84 347 64.86 23 4.30
Change of IAC address + Discontinuity of IAC + Constriction of the IAC diameter 117 1.80 26 22.22 68 58.12 23 19.66
Dark band phenomenom + Change of IAC address + Discontinuity of IAC + Constriction of the IAC diameter 224 3.45 38 16.96 155 69.20 31 13.84
Total 6488 100.00 3033 46.75 3043 46.90 412 6.35  

[i]*Chi-square linear trend test

[ii]**Chi-square test

[iii]Source: by the authors

DISCUSSION

Exodontia of mandibular third molars is a routine procedure in dental practice that, in case of complications, could lead to multiple scenarios. One of them is the injury to the lower dental nerve. In this sense, it is necessary to use diagnostic imaging methods such as the panoramic radiography, which provides with greater precision, a complete view of the number, location, and proximity of the roots to other adjacent structures that may be compromised such as the IAC16,23. However, due to its limitation of only providing two-dimensional information, CBCT is still the most accurate imaging alternative17.

As part of the findings of this investigation, in terms of the proximity of the mandibular third molars, we found that more than three-quarters of the third molars were found close to the IAC. These results coincide with those previously published by Huang et al., who determined that more than 80% of the mandibular third molars contacted or were superimposed on the IAC by using panoramic radiographs of 120 patients from a hospital in Taiwan24. However, there is limited scientific evidence using a standardized classification to identify the proximity of lower third molars to the IAC such as that presented by Langlais et al. and its modification, which is proposed in this paper.

On the other hand, according to Pell and Gregory's classification, the most frequent depth levels in this sample were A and B, together representing almost all the data. Regarding the type A depth level, Jaron et al. evaluated the depth of impaction of third molars with an indication for surgical extraction in the panoramic radiographs of 1585 patients from countries located east of the Baltic Sea, reporting that more than half of the cases showed this Depth25. This result is essential for our research because it coincides with the present study findings. Contrary to our study, an analysis carried out on Turkish people showed that, in the lower jaw, the C classification was the most common according to impaction depth. These findings differ from our study's; this could be related to certain factors like the objective population ethnicity, which is relevant when considering the type of treatment for the patients. Additionally, the auxiliary examinations for the Turkish study belonged to individuals with the indication for exodontia and acute symptomatology such as pain, pericoronaritis, lymphadenopathy, and trismus26.

However, due to the lack of evidence, it has not been possible to identify articles that associate proximity and depth using the same classifications used in this study. Regarding depth, Deshpande et al. demonstrated that digital orthopantomographies are a reliable tool to evaluate depth in third molars impacted with IAC. In addition, they observed that impactions with closer distances to the IAC presented radiographic signs indicating risk and compromising that structure; radiographic findings associated with the proximity between the tooth and the IAC, known as "interruption of the white line," are mentioned27. Similarly, the radiographic analysis allows classifying and determining that those mandibular third molars that maintain close contact with the IAC are linked to a high risk of nerve tissue injury as postoperative sequelae due to their proximity28.

It is important to mention that in this study the proximity to IAC and depth of the lower third molar presented significant differences in their distribution according to age and sex. Similarly, some authors previously state that women present third molars closer and more superimposed to the IAC in comparison to men. In addition, they express specific factors such as age and sex and they present a greater risk of injury to the IAC, according to the location of the structures involved29,30.

Among the limitations observed in this study, we highlight its cross-sectional design, which only allows us to describe the behavior of the variables, but not to infer causal relationships between them. Likewise, the lack of randomization to select the sample, in addition to the presence of non- homogeneous values for each country that allowed us to expose that these findings lack the power to be extrapolated, being only applicable to the sample of this research. In contrast, thanks to technological advances, the use of CBCT is recommended because the location of the mandibular lower third molar can be determined with greater precision.

In this regard, it is important to highlight the contribution that this research makes to the correct pre- surgical diagnosis, due to the high frequency of lower third molars that have close contact with the IAC, which could lead to postoperative complications that, if not considered, are detrimental to the patient. Although panoramic radiographs are widely used in specific contexts, such as countries under evaluation, it is essential to mention that when there is a proximity finding, it would be advisable to complement the diagnosis with a CBCT scan for greater certainty in the localization31. In addition, the findings of this study can be taken as the basis for the generation of further research using panoramic radiographs and the same parameters stablished in this study, including the modified Langlais et al. and Pell and Gregory classifications. Moreover, this is the first published research that modifies the Langlais classification to propose its own classification based on the theory applied to radiographic evidence.

CONCLUSION

According to the modified classification of Langlais et al, the majority of lower third molars in the Latin American population are close to the inferior alveolar canal; and according to the depth classification of Pell and Gregory, the most frequent depths are Positions A and B. In addition, proximity to IAC and depth were associated with each other and with the co-variables country, age, and sex.

ACKNOWLEDGMENTS

The authors would like to thank the students of the second year of the specialty program in Oral and Maxillofacial Radiology of Facultad de Estomatología de la Universidad Peruana Cayetano Heredia since the data presented in their theses facilitated the development of this work.

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[11]To cite as: Garcés-Elías MC, León-Manco RA, Beltrán JA. Proximity to the inferior alveolar canal and depth of third molars in panoramic radiographs of Latin American population. Rev Fac Odontol Univ Antioq. 2023; 35(2): 52-63. DOI: http://dx.doi.org/10.17533/udea.rfo.v35n2a5