Is Panoramic Imaging Equivalent to Cone-Beam Computed Tomography for Classifying Impacted Lower Third Molars?

Assessment of the relationship between the three-dimensional precise location of the mandibular third molar and the volume ratio of the impacted mandibular third molar to the mandibular angle, and the patterns of mandibular angle fracture: A retrospective study

This study aimed to evaluate the relationship between the precise three-dimensional location of the third molar (M3) and mandibular angle fracture (MAF) patterns and to assess the effect of the volume ratio occupied by M3 in the mandibular angle on fracture patterns. The location of M3 was assessed in 218 patients with MAF using computed tomography reconstruction. The bone volume of the mandibular angle and the bone volume occupied by M3 were measured to calculate the volume ratio of M3 to the mandibular angle (M3/MA). MAF patterns were categorized into simple fracture (Type I), displaced fracture (Type II), and comminuted fracture (Type III) based on fracture severity. The results showed that the location of M3 significantly influenced MAF patterns (vertical position: P = .001; horizontal position: P = .002; angulation: P = .027, respectively) and the volume ratio of M3/MA was significantly higher for Type III fracture than Types I and II (P < .001). Regression analysis showed that the horizontal position and angulation of M3 and the volume ratio of M3/MA were the main predictors for comminuted MAF. A larger volume ratio (odds ratio [OR], 1.201; 95% confidence interval [CI], 1.037-1.391; P < .014), Class III position (OR, 7.978; 95% CI, 1.275-49.910; P < .026), and horizontal angulation (OR, 7.212; 95% CI, 1.028-50.581; P < .047) of the M3 were more prone to comminuted MAF than simple fracture. Our findings indicate that the location of M3 significantly affects MAF patterns, and that M3 may weaken the mandibular angle by occupying more bone space, thereby increasing the risk of a comminuted fracture.

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

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

Assessment of relationships between condylar fracture pattern and mandibular third molar position by panoramic radiography and computed tomography: A retrospective comparative study

BACKGROUND/AIM

Although previous studies have revealed the influence of the mandibular third molar (M3) on mandibular condylar fracture risk and that the presence of M3 could result in different incidences of condylar and angle fractures, there have been no analyses of the influence of M3 on fracture patterns. Moreover, evaluations of M3 position using panoramic radiography have shown insufficient accuracy. This study investigated the relationship between condylar fracture patterns and M3 position using panoramic radiography and computed tomography.

MATERIALS AND METHODS

This retrospective study included 280 patients with unilateral mandibular condylar fractures and ipsilateral M3 admitted to West China Hospital of Stomatology between January 2016 and June 2022. Patient medical records, panoramic radiographs, and computed tomography images were collected. The vertical and horizontal positions of M3 were classified using the Pell and Gregory system. M3 angulation was defined as the angle between the long axis of M3 and the mandibular occlusal plane. Condylar fracture patterns were classified as intracapsular (Types A-C) or extracapsular (neck and base). Data were analyzed using McNemar-Bowker test, Pearson chi-squared test, and Fisher's exact test.

RESULTS

Classification of M3 position differed significantly between panoramic radiography and computed tomography images (p < .05). There was a significant association between the mandibular condylar fracture pattern and M3 horizontal position on computed tomography (p < .05). Class I M3 position on computed tomography was associated with a higher incidence of intracapsular than extracapsular fractures, along with a higher incidence of Type B than base fractures; the opposite relationships were observed for Class II. No such association was identified on panoramic radiography.

CONCLUSIONS

Mandibular condylar fracture patterns were presumably influenced by M3 horizontal position on computed tomography. The imaging modality affected the classification of M3 position and subsequent analyses. Computed tomography is recommended for future studies to improve accuracy and reliability.

Reliability of two difficulty indexes in predicting the surgical extraction difficulty of impacted mandibular third molars

Introduction: The aim of this study was to compare the reliability and the agreement of the Pederson and Pernambuco difficulty indexes in predicting the surgical extraction difficulty of the impacted mandibular third molars. Materials and methods: A prospective observational cohort study was conducted on 83 patients who had undergone surgical removal of impacted mandibular third molar. The difficulty of extraction was determined preoperatively according to the total scores obtained from the Pederson and Pernambuco difficulty indexes, the operative difficulty was determined by the surgical technique and the duration of extraction. The accuracy of prediction of the surgical difficulty and the degree of agreement of the two indexes were calculated. Results: The accuracy of Pederson and Pernambuco indexes in predicting the operative difficulty measured by duration of surgery was 36.1% and 55.4% respectively, and with operative difficulty measured by the technique was 21.7% and 37.3% respectively with statistically significant differences. The agreement between the 2 indexes was poor. Conclusion: Both indexes were limited in predicting the surgical difficulty of impacted mandibular third molars although the Pernambuco index was better than the Pederson index and the agreement between the two indexes was poor.

Assessment of lower third molar space: A comparative radiographic study

Objective:

The aim of this study was to assess lower third molar space using four different radiographic reconstructed Cone Beam Computed Tomography (CBCT) images: orthopantomogram, lateral cephalogram, multiplanar CBCT and a newly introduced three-dimensional (3D) simulation technique.

Methods:

The CBCT scans of 32 individuals (20.97 ± 2.152 years) with a total of 50 lower third molars were collected and analyzed. The ratio between the necessary space and available space for lower third molars was calculated on each radiographic reconstructed image. Repeated-measure analysis of variance followed by multiple comparison tests were used.

Results:

The mean ratio was significantly smaller with cephalograms (0.611 ± 0.263), followed respectively by orthopantomograms (0.756 ± 0.221), multiplanar CBCT (0.789 ± 0.191) and 3D simulation technique (0.807 ± 0.193) (p < 0.001). The lowest mean difference was recorded between multiplanar CBCT and 3D simulation technique (0.017). Intra class correlation coefficient was strong (>0.90) for all techniques except cephalograms.

Conclusions:

The assessment of the lower third molar space differs according to the adopted imaging technique. 3D simulation technique is a useful novel technology that allows an exploration of the crown in many different dimensions and orientations, giving more predictable results than the conventional methods.

Radiological risk indicators for persistent postoperative morbidity after third molar removal

OBJECTIVES

Although panoramic radiographs are extensively studied for diagnosis and preoperative planning in third molar surgery, research on the predictive value of this radiographic information regarding the postoperative recovery of patients remains underexploited. This prospective cohort study aimed to assess the potential relationship between radiologic risk indicators and persistent postoperative morbidity, in 1009 patients undergoing 2825 third molar extractions in context of the M3BE study.

METHODS

Two observers evaluated ten radiographic parameters: vertical and horizontal eruption status, third molar orientation, surgical difficulty, nerve relation, maxillary sinus relation, presence of periapical and pericoronal radiolucencies, caries, and third or second molar resorption. Patients' postoperative recovery was recorded 3 and 10 days after surgery. Univariate logistic regression was performed to assess potential associations between radiographic risk indicators and persistent postoperative morbidity.

RESULTS

Deep impactions were significantly associated with the persistence of postoperative pain, trismus and swelling until 10 days after surgery, prolonged need for pain medication, and the inability to resume daily activities and work/studies. Pericoronal radiolucencies and resorption were significantly associated with persistent morbidity and a longer recovery time, whereas caries and periapical lesions were linked to a shorter recovery time.

CONCLUSION

Based on the results of this study, clinicians may better inform patients at risk for persistent postoperative discomfort according to what was preoperatively diagnosed on the panoramic radiograph.

CLINICAL RELEVANCE

Preoperative panoramic radiographs contain information about patients at risk of prolonged recovery after third molar removal. Several risk indicators for persistent postoperative morbidity were identified.

Can diagnostic changes caused by cone beam computed tomography alter the clinical decision in impacted lower third molar treatment plan?

OBJECTIVES

This study observed whether changes in diagnosis caused by analysis of three-dimensional images can lead to alterations in the treatment plans of impacted lower third molars (ILTMs).

METHODS

Sets of panoramic (PAN) - cone beam computed tomography (CBCT) of 218 patients were assessed for ILTM classification, contact with mandibular canal, contact and resorption of the lower second molar (LSM), intraoperative planning and post-operative expectations.

RESULTS

Percentage agreement and McNemar test compared PAN vs CBCT assessments. Logistic regression analyzed the dependency of change in surgical planning considering the changes in diagnostic features; descriptive statistics was used to observe the expectation of post-operative complications and paresthesia. Differences were found between PAN vs CBCT for classification of impaction and positioning, LSM relationship, choice for crown and root sectioning and expectation of post-operative complications (all with p < 0.001). Logistic regression indicated that the change in diagnosis caused by CBCT examination did not change the clinical decision to extract ILTM but altered the planning of intraoperative steps such as osteotomy, crown sectioning and relaxing incision. The expectation of post-operative complications decreased when professionals planned the ILTM removal using tri-dimensional images.

CONCLUSIONS

We concluded that changes in the diagnosis after CBCT examination can lead to alterations in the treatment plan of impacted lower third molar.

Marginal bone loss in the second molar related to impacted mandibular third molars: comparison between panoramic images and cone beam computed tomography

BACKGROUND

Deciding whether or not to extract third molars remains a controversial situation in dental practice. Image exams support this decision by enabling a close view of the third molar, its adjacent bone and its relationship with the second molar. This study aimed to assess and compare second molar bone loss adjacent to impacted mandibular third molar in panoramic radiographs (PAN) and cone beam computed tomography (CBCT) scans.

MATERIAL AND METHODS

A sample of 70 patients was selected (n=124 teeth). Each patient had a set of a panoramic radiograph and CBCT scans consecutively taken for dental treatment purposes. In PAN and CBCT, mandibular third molars were classified based on their position and bone loss of the adjacent second molar. Agreement between PAN and CBCT scans was assessed and quantified.

RESULTS

Outcomes of bone loss assessment were different between PAN and CBCT scans (p<0.05). Bone loss was found in 62.9% of the PAN, while in CBCT scans it was found in 80%. In particular, nearly 29% (n=27) of the teeth that were classified without bone loss in PAN were classified with bone loss in CBCT scans. Mesioangular and horizontal third molars had a statistically significant association with bone loss of the adjacent second molars (p<0.05). In general, PAN underestimated the severity of bone loss compared to CBCT scans (p<0.05).

CONCLUSIONS

Diagnosing second molar bone loss due to impaction of adjacent third molar in PAN may be challenging because of false negatives. Impacted third molars justify preoperative CBCT scans if second molar bone loss needs to be precisely assessed for a more detailed and reliable treatment plan.

Identification of Specific Panoramic High-Risk Signs in Impacted Third Molar Cases in Which Cone Beam Computed Tomography Changes the Treatment Decision

PURPOSE

The aim of this study was to investigate the treatment decisions of oral-maxillofacial surgeons in the management of impacted lower third molars (M3s) according to panoramic radiography (PR) and cone beam computed tomography (CBCT) risk analysis.

PATIENTS AND METHODS

Ten surgeons analyzed 40 deliberately selected M3 cases showing 1 or more panoramic high-risk signs: 1) darkening of the root, 2) interruption of the white line, 3) diversion of the inferior alveolar canal (IAC), 4) narrowing of the IAC, and 5) 2 or more signs occurring simultaneously (including darkening and/or interruption of the IAC). After evaluating the PR images, the observers analyzed the patients' CBCT images. The treatment decision (extraction vs coronectomy) and surgical technique (number of planned tooth sections) were recorded.

RESULTS

On the CBCT coronal slices, direct contact between the M3 and IAC, together with narrowing and/or fenestration of the IAC, was observed most frequently when 2 or more panoramic signs were seen simultaneously on the PR images (odds ratio [OR], 7.2; P = .021). CBCT findings led to a significant decrease in the number of coronectomy decisions (23% vs 14.5%, P = .002), which was most prominent in the groups showing panoramic signs of darkening (approximately 50%, P = .007) and narrowing (approximately 66%, P = .044). A significant number of extraction decisions were modified to coronectomy when 2 or more panoramic signs occurred together (OR, 7.9; P < .001). However, there were no significant differences regarding the number of planned hypothetical tooth sections.

CONCLUSIONS

The results showed that the surgeons' confidence in the treatment decision increased after CBCT imaging, resulting in fewer coronectomy decisions. CBCT information that changed a previous coronectomy decision to extraction was most frequently observed in cases showing darkening and narrowing PR signs. The chance of changing an extraction decision to a coronectomy decision after evaluating the patient's CBCT images was the highest when 2 or more PR signs were observed simultaneously.