Position Of Third Molars Research Articles

Prevalence of third molar impaction in patient with mandibular anterior teeth crowding

Introduction: Third molar impaction has been a controversial topic among clinician when it comes to mandibular anterior teeth crowding. The aim is to know the prevalence of third molar impaction in patient with mandibular anterior teeth crowding in Orthodontic Department, RSGM UNPAD, Indonesia. Methods: This was a descriptive research, with non-probability sampling obtained from a population with full arch 32 teeth. Totaling 54 samples from year 2011 to 2014 were obtained. The age of sample range from 15 to 25 years old. Also all panoramic radiographs taken from the year 2011 to 2014 were examined using a computer. The position of third molars were determined by Winter’s classification using angle formed between the intersected longitudinal axes of the second and third molars and anterior teeth status by using Little’s irregularities index. Results: This study obtained data that as much as 68.52% mesioangular third molar, 19.44% distoangular, 4.63% horizontal, 1.85% buccolingual and 0% others. In mesioangular impaction condition there was crowding 83.78%, in distoangular condition there was 100% crowding, in horizontal position crowding found 100%, while at buccolingual crowding found 100%.Conclusion: In all positions the third molar impaction was accompanied by crowding of the mandible anterior teeth, with the largest percentage of impaction was the mesioangular position

Correlation of Third Molar Status with Incidence of Condylar and Angle Fractures.

The mandibular angle and condylar regions are most prone to fractures and this has been attributed to the presence/absence or the position of the third molars. This retrospective study was undertaken to analyze the correlation between the third molars and incidence of condylar and angle fractures in 104 patients treated for these fractures during the period from June 2009 to December 2013. Clinical and radiographic records of these patients were studied to look for the presence and position of third molars and their relation to incidence of condylar or angle fractures. There was a definite positive relation to impacted third molars and increased incidence of angle fractures. The condylar fractures were more commonly seen when the third molars were fully erupted or missing. Third molar impactions predispose to angle fractures and missing or fully erupted third molars predispose to condylar fractures.

A multi-centre retrospective study of mandibular fractures: do occlusal support and the mandibular third molar affect mandibular angle and condylar fractures?

This retrospective study was performed to investigate the influence of occlusal support and the presence, state, and position of mandibular third molars on the incidence of mandibular angle and condylar fractures. The following variables were investigated: age, sex, cause of fracture, presence and state (impaction, angulation, and the number of roots) of the mandibular third molars, site of the mandibular fracture, presence of occlusal support, duration of intermaxillary fixation, and postoperative complications. Various risk factors for mandibular angle and condylar fractures were investigated by univariate analysis. The risk of mandibular angle fracture was significantly higher in patients with occlusal support and mandibular third molars. The risk of condylar fracture was significantly higher in patients without occlusal support or mandibular third molars. The position and angulation of the mandibular third molars were not significant risk factors in mandibular angle and condylar fractures. This study demonstrated the influence of occlusal support and the presence of mandibular third molars on the incidence of mandibular angle and condylar fractures. The presence of occlusal support may be a more important factor affecting mandibular angle or condylar fractures than the position of the mandibular third molars.

Saving the 2(nd) Molar from the 3(rd) Is it Really the Guilt of the Tilt?

Clinicians often relate the distal caries in second molars to angulated third molars, which if left undetected can lead to gross decay that may further require removal of the tooth. Due to this fact, many third molars are advised for prophylactic removal to prevent decay in the second molar. But this approach would only be justified when the incidence of decay/loss of second molar due to third molar are reasonably high. We sought to determine incidence of caries experience and also sequel extraction in second molars associated with the third molars. The study was conducted to answer the basic question that whether the incidence of caries and subsequent extraction of second molar due to angulated third molars is high enough to justify the prophylactic removal of third molar or not. This study was conducted on radiographic records of 1187 patients. The effect of tilted third molar on the second molar was measured in relation with three parameters namely level & position of third molar with respect to second molar and the distribution among arches. The results indicated that out of total number of teeth examined only 5.4% of maxillary and 9.6% of mandibular second molars were affected by tilted third molars. Further, only 2.2% of mandibular and 2.9% of maxillary second molars were indicated for extraction. The data was statistically insignificant. It was concluded that distal caries in second molars is not very common. It may be present in some cases of third molar impactions and prophylactic removal of these impacted teeth may not be considered appropriate.

Evaluation of the maxillary third molar position and its relationship with the maxillary sinus: a CBCT study

The present study investigated the position and relationship of the maxillary third molars to the maxillary sinus. These molars were detected to have a close relationship with the maxillary sinus based on panoramic images, using cone-beam computed tomography (CBCT). This retrospective study evaluated 162 impacted third molars from 100 patients that showed a superimposed relationship between the maxillary sinus and third molars on panoramic images obtained from CBCT. CBCT images were used to assess the horizontal (buccopalatal) and vertical positions of the maxillary sinus relative to the maxillary third molars, proximity of the roots to the sinus, and angulation and depth of the third molars. The associations among the angulation, depth of third molars, and horizontal and vertical positions of the maxillary sinus relative to the third molar findings were examined using Chi square tests. Based on the winter classification, the most frequent tooth position was vertical (59.9 %), followed by mesioangular (14.2 %), distoangular (9.9 %), and others. Most impacted teeth were at the level between the occlusal and cervical levels of the adjacent second molar. Regarding the relationships of the maxillary third molars with the maxillary sinus examined on CBCT, vertical type III (buccal root related with maxillary sinus) (34 %) and horizontal type 2 (maxillary sinus located between roots) (64.8 %) were seen most frequently. The relationship between the maxillary sinus and third molar roots should be considered during extraction. When a risk of sinus perforation is predicted in an extraction, a presurgical CBCT examination could be valuable.

Recurrent pain and swelling associated with impacted maxillary third molar

A 57-year-old woman reporting intermittent severe pain and swelling for 5 years in the left maxillary jaw was evaluated at the oral and maxillofacial surgery clinic at the University of Detroit Mercy School of Dentistry. The pain intensity had increased markedly in the past 2 to 3months. She had difficulty swallowing and opening her mouth, and a bad odor associated with a bloody mucous discharge. Her medical and surgical history included chronic neck pain, arthritis, degenerative disk disease, choroid cyst, headaches associated with Arnold-Chiari malformation, sinus surgery due to recurrent sinusitis, and an eye surgery for strabismus. Her dental history included periodic pain and soreness associated with impacted tooth no. 16. Her health history included a 40 pack-year smoking history, and at the time of her examination she was smoking 1 pack per day. She denied alcohol or illicit drug use. Extraoral examination identified a nonerythematous, firm swelling on the left side of her face without evidence of lymphadenopathy. On the basis of the long-standing pain and swelling, the difficulty in opening, and the history of surgery in the left maxillary sinus, the decision was made to examine the patient with cone-beam computed tomography (CT). This technique permits a view of the anatomy in 3 planes of space. It also provides a larger field of view than panoramic radiographs, which was especially beneficial due to the unknown position of the left third molar. The cone-beam CT scan revealed diffuse opacification of the left maxillary sinus with destruction of the alveolar process and resorption of the walls of the maxillary sinus. The pathologic alterations extended beyond the field of view, and considering the likely involvement of extra-antral soft tissues it was decided that CT was necessary for complete radiographic visualization of the condition. A bone window axial view of the CT scan revealed the lesion in the left maxillary sinus associated with destruction of the anterior, posterior-lateral, and medial walls of the left maxillary sinus, with extension into the pterygopalatine fossa as well as the buccal and masticator spaces (Figure 1). Soft-tissue sections depicted infiltration of the lesion into the medial and lateral pterygoid muscles, and extension into the nasal fossa (Figure 2) and greater palatine foramen (Figure 3). Destruction of the palate and left maxillary alveolar ridge was also observed (Figure 4). Microscopic examination after an incisional biopsy revealed a proliferation of squamous epithelium. Cells exhibiting increased nuclear-cytoplasmic ratios, pleomorphism, individual cell keratinization, and increased mitotic activity were noted (Figure 5).

Impact of the lower third molar presence and position on the fragility of mandibular angle and condyle: A Three-dimensional finite element study

The aim of the present study was to investigate the influences of the presence and position of a lower third molar (M3) on the fragility of mandibular angle and condyle, using finite element analysis. From computed tomographic scans of a human mandible with normally erupted M3, two additional virtual models were generated: a mandibular model with partially impacted M3 and a model without M3. Two cases of impact were considered: a frontal and a lateral blow. The results are based on the chromatic analysis of the distributed von Mises and principal stresses, and calculation of their failure indices. In the frontal blow, the angle region showed the highest stress in the case with partially impacted M3, and the condylar region in the case without M3. Compressive stresses were dominant but caused no failure. Tensile stresses were recorded in the retromolar areas, but caused failure only in the case with partially impacted M3.In the lateral blow, the stress concentrated at the point of impact, in the ipsilateral and contralateral angle and condylar regions. The highest stresses were recorded in the case with partially impacted M3. Tensile stresses caused the failure on the ipsilateral side, whereas compressive stresses on the contralateral side.

Radiographic Assessment for Predicting the Mandibular Third Molar Eruption after Orthodontic Treatment in First Premolar Extraction Group and Non-Extraction Group: A-retrospective Study

Introduction: The third molars are the most congenitally missing teeth. If present, they might follow ectopic eruption path and become impacted. Because it is the last tooth erupt in the arch, and usually there is no space in the arch. Effects of orthodontic treatment may also affect the position of third molar after treatment and may changes the eruption pattern of third molar. Materials and Methods: 30 patient’s pre-treatment and post-treatment lateral cephalogram and orthopantomogram (OPG) were taken out of which 15 patients were treated with first pre-molar extraction, and 15 patients were treated with non-extraction approach. Cephalomatric and OPG tracing were done at T1 (pre-treatment) and T2 (post-treatment). Distance from Xi-point to distal surface of second molar, distance from anterior border of ramus to the distal surface of second molar, angulation of third molar in relation with second molar and mesio-distal width of third molar were checked. Descriptive analysis was perform for both the groups and paired t-test and un-paired t-test were performed for first pre-molar extraction and nonextraction group with two different methods such as panoramic radio graph (OPG) and lateral cephalograms at significant level P < 0.05. Results: In extraction group, there were more possibility of the eruption, more mesial movement and more angulation changes noted compare to non-extraction group. Conclusion: Panoramic radiographs were more accurate when compared to lateral cephalogram while checking minor changes.

The relationship of the inferior alveolar nerve canal with the roots of impacted mandibular third molars in a group of the South Indian population

Aim/Objective: The aim of this study was to evaluate the topographic relationship between the inferior alveolar nerve canal (IANC) and the roots of impacted mandibular third molars. Materials and Methods: The study conducted at the Department of Oral Medicine and Radiology, Maratha Mandals NG Halgekar College of Dental Sciences and Research Center, Belgaum, Karnataka, India. A total of 100 patients (54 female and 46 male) visiting the outpatient department between the age group of 18 and 50 years, with a mean age of 24 years, were selected. Before starting the study, ethical clearance was taken from the ethical committee and informed consent was taken from each patient who underwent radiographic examination. The study included only those patients who had a full set of dentition in their mouth visible clinically. No cases with history of extraction or invisible (agenesis) cases were included in our study. Pre-operative orthopantomograms (OPGs) were examined and the proximity of the IANC to the roots of impacted mandibular third molars was categorized into the following groups: Superimposition, adjacent, perforation, grooving, notching or none. The categories notching, grooving and perforation were regrouped together and called the true relationship between the IANC and the root apices. The type of impaction, age and sex of the patient were also noted. Results: The greater number of impacted third molars was of mesioangular position and accounted for 98 (49%) of the total sample. Only six (3%) third molars were classified under the classification as aberrant. The prevalence of the impacted third molar was more common in the 18-30-year-old age group, with the mesioangular (98 [49%]) type of impaction being the most common type. The position of the IANC showed that 50 (25%) teeth were of superimposition, 41 (20.5%) teeth were of adjacent, 49 (24.5%) teeth were of grooving, 17 (8.5%) teeth were of notching and 30 (15%) teeth were of perforating categories in relation to the IANC. The remaining 13 (6.5%) teeth could not be placed under any of these categories and, therefore, were placed in the category none. The relationship between the IANC and the angular position of the mandibular third molars was found to be more common in mesioangular impactions (49%) than in any other type of impaction. Six impacted molars were in aberrant impaction (3%), and these fell into the superimposition category. Conclusion: The position of the IANC in relation to the roots of the impacted third molars varied according to the patient's age.

Difficulty index in extraction of impacted mandibular third molars and their post-operative complications

Background: Although the removal of impacted mandibular third molars is a common minor oral surgical procedure, the extraction of these teeth can present with certain post–operative complications. Koerner KR proposed a Difficulty Index Scale for removal of these teeth on the basis of local anatomy and radiographs, which were helpful in predicting the difficulty that would be encountered intra-operatively, as well as the post-operative complications. Objective: To study the different post-operative complications in the removal of impacted mandibular third molars calculating their difficulty index value. Method: A total of 119 patients, 79 females and 40 males who underwent extraction of their impacted third molars were selected over a one year period. Data were collected prospectively, according to the angulation, depth and position of the impacted mandibular third molars and their difficulty index calculated. This was further correlated with the postoperative complications encountered. Results: Mesio-angular impaction (43.7%), with level A (66.4%) and Class I (70.6%) impaction were the major type of impaction seen. The difficulty index showed that majority were in the moderately difficult category (51.2%), with swelling and trismus seen to increase as the difficulty index value increased. Females were affected more than males, with swelling (Odds ratio 2.206) and trismus (Odds ratio 2.570) seen to be significantly more. Conclusion: Surgical removal of impacted mandibular third molars causes post-operative complications and special care is required in their removal, especially in females. The Difficulty Index, as described by Koerner KR can be used as a tool for predicting the frequency of the post-operative complications, especially swelling and trismus. DOI: http://dx.doi.org/10.3126/jkmc.v3i1.10918 Journal of Kathmandu Medical College Vol. 3, No. 1, Issue 7, Jan.-Mar., 2014, Page: 14-20

The Effect Of Class III Orthopedic Treatment On Position And Development Of Impacted Mandibular Third Molar: A Longitudinal Study

The third molars, and particularly those in the lower jaw, are the most frequently impacted teeth. The reason for third molar impaction, particularly of the lower molars is not absolutely clear. Several factors such as morphology, mesiodistal width of teeth, alveolar arch space behind the second molars, unfavorable path of eruption, and unsatisfactory uprighting during eruption have been associated with third molar impaction. While different methods have been developed to predict whether a molar will erupt or become impacted, no model has been able to reliably predict whether a molar will erupt or become retained. Yet, the risk of third molar impaction was reduced by an increase in retromolar space due to mandibular first premolar extraction1 and mesial molar movement2 during orthodontic treatments. However, we are aware of no studies evaluating the effect of Class III orthopedic treatment on the position and development of mandibular third molars, and retromolar space. The purpose of this study is to evaluate and to compare the position, inclintion of mandibular right and left third molars after Class III orthopedic treatment and long term follow-up.

Incidence of impacted third molars: A radiographic study in People's Hospital, Bhopal, India

ObjectivesThe aim of this study is to evaluate the position of impacted third molars based on the classifications of Pell & Gregory and Winter in a sample of Bhopal patients. Study designIn this retrospective study, up to 1100 orthopantomograms (OPG) of the patients who were reported to the MaxilloFacial Department of PDA and Chowdhary hospital from January 2011 to December 2012 were evaluated. ResultsAmong 1100 patients, 730 were male and 370 were female patients. Of the 1100 OPGs studied, 3,910 third molars were noticed either impacted or erupted and 490 third molars were missing. The most common angulation of impaction in the mandible was in vertical position (41.4%) followed by mesioangular impaction (33.3%) and the most common angulation of impaction in the maxilla was the vertical (67.4%) which was followed by 15.2% in distoangular impaction.The level of eruption of impacted third molar was found to be 43.9% at level A, 34.8% at level B and 21.3% at level C. There was no significant difference between the right and left sides in both the jaws. ConclusionThe pattern of third molar impaction in the region of Bhopal is characterized by a high prevalence of impaction, especially in the mandible. The most common angulation was the vertical in the mandible as well as in the maxilla. The most common level of impaction in mandible was level A and in maxilla is level C and there was no any significant difference between the right and left sides in both jaws.

Does the Presence or Position of Lower Third Molars Alter the Risk of Mandibular Angle or Condylar Fractures?

The purpose of this study was to determine whether a relation exists between the presence of mandibular third molars (M3s) and mandibular angle and condylar fractures and whether the risk of these fractures varies with M3 position. A retrospective cohort study was conducted in patients with mandibular fractures presenting to the oral and maxillofacial surgery service from April 2007 to March 2012. Data sources were patients' hospital charts and panoramic radiographs. Predictor variables were the presence and position of M3s. M3 position was based on the Pell and Gregory classification and angulation was determined by measuring the angle between the long axis of the M3 and the mandibular occlusal plane. Outcome variables were the presence of angle and condylar fractures. Other study variables included age, gender, and fracture etiology. Data were analyzed using the χ(2) test and Student t test. The study sample consisted of 446 patients with 731 mandibular fractures. Results showed that the risk of mandibular angle fracture was significantly higher in patients and mandible sides with impacted M3s (P < .001), whereas the risk of condylar fracture was significantly higher in patients and mandible sides lacking impacted M3s (P < .001). A relation between the position of M3s to angle or condylar fractures could not be found (P > .05). The presence of impacted M3s increased the risk of angle fracture and simultaneously decreased the risk of condylar fracture. However, no relation appeared to exist between M3 position and fracture pattern.

Impacted mandibular third molars and their influence on mandibular angle and condyle fractures – A retrospective study

BackgroundPrevious retrospective analyses prove that impacted mandibular third molars (M3s) increase the risk of angle fractures and decrease the risk of concomitant fractures to the condyle. Study designA retrospective cohort was designed for patients reported to the Department of Oral and Maxillofacial Surgery from January 2011 till June 2013. The study variables are presence or absence of third molar, if it is present, their position, classified using the Pell and Gregory system; angulation, classified using Shiller's method. The outcome variables were angle and condyle fractures. Materials and methodsHospital records and panoramic radiographs were used to determine and classify these variables.The study sample comprised of 118 mandibular angle and condyle fractures in 110 patients.Database was constructed and analysed using SPSS version 10.0. ConclusionThis present retrospective study concluded that the presence of impacted third molar predisposes the angle to fracture and reduces the risk of a concomitant condylar fracture. However absence of impacted third molar increases the risk of condylar fracture. The highest incidence of angle fracture was observed in position A impacted mandibular third molars. And there is no significant relationship, concerning ramus position and angulation of impacted mandibular third molars with the angle fracture.

Position of impacted mandibular third molar in different skeletal facial types: First radiographic evaluation in a group of Iranian patients

PurposeThis study was performed to evaluate the position of impacted mandibular third molars in different skeletal facial types among a group of Iranian patients.Materials and MethodsA total of 400 mandibular third molars in 200 subjects with different types of facial growth were radiographically investigated for their positions according to their types of facial growth on the basis of the β angle. The subjects were divided into three groups (class I, II, and III) according to ANB angle, representing the anteroposterior relationship of the maxilla to the mandible. Meanwhile, the subjects were also divided into three groups (long, normal, and short face) according to the angle between the stella-nasion and mandibular plane (SNGoGn angle). ANOVA was used for statistical analysis.ResultsThe mean β angle showed no significant difference among class I, II, and III malocclusions (df=2, F=0.669, p=0.513). The same results were also found in short, normal, and long faces (df=1.842, F=2, p=0.160). The mesioangular position was the most frequent one in almost all of the facial growth patterns. Distoangular and horizontal positions of impaction were not found in the subjects with class III and normal faces. In the long facial growth pattern, the frequency of vertical and distoangular positions were not different.ConclusionIn almost all of the skeletal facial types, the mesioangular impaction of the mandibular third molar was the most prevalent position, followed by the horizontal position. In addition, β angle showed no significant difference in different types of facial growth.

Correlation of Mandibular Second Molar Impaction with Third Molar Size, Angulation, Developmental Stage, and Bud Position

Objective: The present study assessed the association of size, axial angulation, developmental stage and bud position of the mandibular third molar with the second molar impaction in patients with mandibular second molar impaction. Methods: In this descriptive-analytical study (Case-Control Design), dental records of 5,420 patients in the age range of 12-15 years who underwent orthodontic treatment were assessed out of which 20 patients (14 females and 6 males) with lower second molar impaction were studied. Twenty control patients with erupted second molars were selected from the same centers and matched with the case group. Total sample size was 40 (Case and Control) and had normal distribution for the determined measurements. Third molar axial angulation towards the second molar, first molar and mandibular base, mesiodistal width of 3 rd molar /2nd molar ratio, Nolla developmental stage and third molar bud position were measured and calculated in patients with impacted and erupted second molars and analyzed using student t and chi-square tests. Results: The mean degree of third molar angulation towards the second molar, first molar and mandibular base was 30.20, 53.6, and 51.3 degrees in cases and 21.4, 34.65 and 45.15 degrees in controls, respectively. Significant differences were found between the two groups in terms of third molar angulation towards the second molar (30.2 Vs 21.4 degrees p<0.047), and first molar (53.6 Vs 34.65 degrees p<0.0001); while no differences were found between the two groups in terms of third molar angulation towards the mandibular base (51.3 Vs 45.15 degrees). The mean mesiodistal width of third molar/ second molar ratio was 0.99 in cases and 0.95 in controls with no significant difference. Nolla developmental stage and position of the marginal ridge of the third molar bud towards the second molar showed no definite relation with second molar impaction. Conclusion: It seems that angulation of third molar to the second and first molars is a major contributing factor to increase the risk of second molar impaction. Third molars size, developmental stages, and bud positions, do not show a significant relation to the second molar impaction.

Prevalence and type of pathological conditions associated with unerupted and retained third molars in the Western Indian population

Aim: The aim of this retrospective study was to assess the position of impacted third molars and to determine the prevalence and type of pathological conditions associated with these unerupted and retained teeth in the Western Indian population. Materials and Methods: A total of 5486 impacted third molars of 4133 patients were studied through the panoramic radiographs and clinical records to determine the position of the impacted third molars and for the presence of associated pathology. The ages of the patients ranged from 17 years to 67 years, with a mean of 33.7 years. The ratio of male to female patients was 1.8:1. The ratio of maxillary to mandibular molars was 1:1.6. Results: Pericoronitis was the most common associated pathology with the third molars (38.9%), followed by dental caries seen in 13.2% of the impacted teeth. Cystic and neoplastic changes were seen around 3.6% impacted teeth and 5.3% adjacent second molars had caries. Other pathologies were less frequent. Conclusion: The prevalence of pathological conditions associated with the third molar in the Western Indian population was 69.73%. Pericoronitis and caries were commonly seen in relation to the impacted third molars, whereas cystic pathology and root resorption were rarely observed. The fact that a considerable number of patients were asymptomatic indicating pathology is certainly worth considering.

Study of position and eruption of lower third molars in adolescents

Introduction: The occurrence of retained lower third molars (3M) is common. A careful analysis is necessary for proper clinical management and the radiographic examination is fundamental. The use of panoramic radiographs is extremely important for the analysis and classification of 3M position, allowing the diagnosis and the establishment of the treatment planning for the removal of these teeth. Objective: The aim of this study was to evaluate the changes in position and eruption state of lower 3M during a period of 3.6 years, as well as to identify factors that may be related with early diagnosis of dental retention of these teeth in adolescent patients. Material and methods: One hundred and one initial (T1) and final (T2) panoramic radiographs from patients treating at the university’s orthodontic clinics were analyzed. The distribution of 195 lower 3Ms was evaluated taking into account personal data, collected from clinical records. The data obtained in relation to the positioning of the teeth were based on the ratings of Winter and Pell &amp; Gregory. Results: The results showed that vertical position was the most prevalent and the C level and class II positions were predominant. The changes occurring in 3M position during the study interval were not statistically significant. Conclusion: After the final evaluation (T2) it was concluded that unpredictable changes in lower 3Ms position and eruption may occur. The variables race (P = 0.03) and anterior border of the mandibular ramus (P = 0.007) seem to have influence on the level of eruption, also suggesting influence on this tooth retention within dental arches over the years.

Incidence of impacted mandibular and maxillary third molars-a radiographic study in a Southeast Iran population

Objectives: The aim of this study is to evaluate the position of impacted third molars based on the classifications of Pell & Gregory and Winter in a sample of Iranian patients. Study design: In this retrospective study, up to 1020 orthopantomograms (OPG) of the patients who were referred to the radiology clinics from October 2007 to January 2011 were evaluated. Data including the age, gender, the angulation type, width and depth of impaction were evaluated by statistical tests. Results: Among 1020 patients, 380(27.3%) were male and 640(62.7%) were female with the sex ratio was 1:1.7. Of the 1020 OPGs, 585 cases showed at least one impacted third molar, with significant difference between males (205; 35.1%) and females (380; 64.9%) (P = 0.0311). Data analysis showed that impacted third molars were 1.9 times more likely to occur in the mandible than in the maxilla (P =0.000). The most common angulation of impaction in the mandible was mesioangular impaction (48.3%) and the most common angulation of impaction in the maxilla was the vertical (45.3%). Impaction in the level IIA was the most common in both maxilla and mandible. There was no significant diffe-rence between the right and left sides in both the maxilla and the mandible. Conclusion: The pattern of third molar impaction in the southeast region of Iran is characterized by a high prevalence of impaction, especially in the mandible. Female more than male have teeth impaction. The most common angulation was the mesioangular in the mandible, and the vertical angulation in the maxilla. The most common level of impaction was the A and there was no any significant difference between the right and left sides in both jaws. Key words:Third molar, impaction, incidence, Iran.

Changes in the Position of Mandibular Third Molars Following Extraction and Non-Extraction Orthodontic Treatments

Introduction: Impaction of third molars can be associated with a number of sequelae, each requiring a different type of treatment. The purpose of this study was to assess the changes in the position of lower third molars following extraction and non-extraction orthodontic treatments. Methods: Pre- and post-treatment panoramic radiographs of 26 class I malocclusion patients (4 male and 22 female) who were treated on a non-extraction basis were compared with those of 30 class I malocclusion patients (5 male and 25 female) who received orthodontic treatment following the extraction of all first premolars. In each group, the lower third molar angulations and their distance from the lower border of the mandible were assessed. Results: Paired t-tests and independent t-tests detected significant changes in the position of the lower third molars in the extraction group. Both the left and right molars became more upright and their distance from the lower border of the mandible increased. Similar changes were only seen in the position of the right mandibular third molars in the non-extraction group. Conclusion: Tooth extractions can bring about favorable changes in the position of mandibular third molars and possibly reduce their incidence of impaction