Does cone beam CT change the treatment decision for maxillary second and third molars? A prospective study.

OBJECTIVES: To evaluate whether information from CBCT changes the treatment plan for maxillary second and third molars and to examine clinical and radiographic parameters with an impact on treatment decision. METHODS: This prospective study included 260 maxillary third molars with superimposition onto the second molar in panoramic images (170 patients; mean age 28 years, range 16-63). An initial treatment plan was based on clinical findings and panoramic images. After CBCT, a final treatment plan was decided. Treatment was undertaken based on the final treatment plan. Through logistic regression analyses, impact of clinical and radiographic parameters on change in treatment plan, removal of the third molar vs no treatment, and removal of the second vs third molar were evaluated. RESULTS: The treatment plan changed in 82 cases (32%). Sixteen cases (6%) changed from removal of the third molar to removal of the second molar. Regression analyses showed that severe resorption in the second molar was significantly related to a change in treatment plan. Removal of a third molar was decided in 180 cases and regression analyses identified that mesioangulation of the third molar, marginal bone loss, superficial resorption, and age were significantly related to removal of the third molar vs no treatment. Thirty second molars were removed, and regression analyses showed that severe resorption was significantly related to removal of the second molar instead of the third molar. CONCLUSIONS: Parameters such as resorption evaluated in CBCT can modify the treatment decision, resulting in removal of the second and/or the third molar.

Risk factors observed in 2-dimensional radiographs for permanent injury of the inferior alveolar nerve after removal of mandibular third molars: a case-control study.

OBJECTIVE: To assess whether differences exist in signs observed in 2D radiographs of mandibular third molars between a case group of patients with and a control group without permanent sensory disturbance of the inferior alveolar nerve (IAN) after removal. STUDY DESIGN: Three observers blinded to patient status assessed radiographs from the case group (n=162) and the control group (n=172). Two new signs, craniocaudal relation of the roots and the mandibular canal and position of the canal over the roots; and 4 "classic" signs, interruption of the white borders of the canal, darkening of the roots, narrowing of the canal lumen, and diversion of the canal over the roots were registered. Chi-square tests assessed differences in distribution of radiographic signs between the groups. Odds ratios expressed the association between radiographic signs and permanent sensory disturbance. Inter- and intraobserver reliability values were calculated. RESULTS: We found significantly more teeth with roots positioned inferiorly to the canal borders (P<0.001; OR 4.1-5.3) and with the canal superimposed over the upper or middle third of the roots (P<0.001; OR 2.6-3.9) in the case group than in the control group. Inter- and intraobserver reproducibility was excellent for roots inferior to the canal borders and fair to good for canal superimposition. CONCLUSIONS: Two radiographic signs are valid predictors of permanent sensory disturbance of the IAN in 2D radiographs.

Reliability of radiographic findings in large FOV CBCTs of mandibular third molars as basis for pre-operative patient information.

OBJECTIVE: The aim of this study was to assess the relation between radiographic findings in large field of view (FOV) cone beam computed tomography (CBCT) exams and clinical findings of mandibular third molars in relation to the pre-operative patient information. MATERIAL AND METHODS: Two hundred and nine mandibular third molars in 134 orthognathic patients examined with CBCT were removed. Three observers assessed tooth- and mandibular canal-related variables in CBCT images, and the findings were correlated to clinical findings during surgery for all observers: tooth angulation, number and morphology of roots and close relationship between the tooth and the mandibular canal. Moreover, positive (PPV) and negative (NPV) predictive values and positive (LR+) and negative (LR-) likelihood ratios were calculated for the canal-related variables. Inter- and intra-observer reproducibility was expressed as percentage accordance and kappa-statistics. RESULTS: Generally, there was high correlation between radiographic and clinical tooth-related variables. The opposite was true for the canal-related variables, since the PPV and LR + were low. The highest PPV and LR + were found when the mandibular canal was positioned between the roots of the third molar. CONCLUSIONS: Tooth-related findings in CBCT are reliable, whereas mandibular canal-related findings should not affect the information provided to the patient pre-operatively.

Head motion and perception of discomfort by young children during simulated CBCT examinations.

OBJECTIVES: To assess the frequency and characteristics (number, complexity, and distance) of head movements, and the perception of discomfort during simulated CBCT examinations in children, considering units with different patient positioning method and head immobilization device combinations. METHODS: Forty children (20 boys/20 girls, age range 10-14 years) were video-recorded during simulated CBCT examinations. Children were randomly allocated to a sequence of five CBCT units: Newtom-5G, Orthophos-SL, Cranex-3Dx (patient standing/sitting), and X1. The child scored his/her discomfort perception (visual scale) and the preferred/ill-favored unit. Three observers scored the videos (20% in duplicate): child movement (yes/no), number (<3/≥3/continuous), complexity (uniplanar/multiplanar) and distance (<3 mm/≥3 mm). κ statistics provided intra-/interobserver reproducibility. Severe/extreme motion was defined based on movement characteristics. Chi-square tests assessed the frequency differences of severe/extreme motion among the units, age and operator. Logistic regression analyses with severe/extreme motion as outcome were performed. RESULTS: The range of intra- and inter-observer reproducibility for movement observation was 0.78-0.89 and 0.61-0.64, respectively. Between 60% (Newtom-5G) and 100% (X1) of children moved during the examination. Severe/extreme motion was significantly related to unit and age. There was significantly less severe/extreme motion, when the child was in the supine position with a foam headrest as head support. The younger the child, the higher the risk for severe/extreme motion. The majority of the children preferred the unit with the supine position and a foam headrest. CONCLUSIONS: The prevalence of severe and extreme motion was associated with the unit's patient positioning method and head immobilization devices combined, and child age.

Impact of CBCT on treatment decision related to surgical removal of impacted maxillary third molars: does CBCT change the surgical approach?

OBJECTIVES: To assess factors influencing treatment decision for maxillary third molars referred for cone beam CT (CBCT). Parameters influencing the decision to treat and to remove either the maxillary second molar or third molar were pursued. METHODS: 111 impacted maxillary third molars, clinically examined including a panoramic image, in 86 patients (mean age 26 years, range 15-55) were referred for CBCT on suspicion of pathology/root resorption in the second molar, based on information in the panoramic image. The following parameters were assessed from the patient's file, including the radiographic images: (1) third molar angulation; (2) initial treatment plan based on clinical examination and the panoramic image; (3) diagnoses based on information from CBCT; (4) treatment decision after additional CBCT information was available; (5) pre-/post-operative complications; (6) treatment of the maxillary second molar. RESULTS: 70 cases (63.1%) underwent treatment, while 41 (36.9%) received no treatment. Change in treatment plan was registered in 65 cases (58.6%) after CBCT. In 12 cases (10.8%), treatment changed from removal of the third to removal of the second molar, while 25 (22.5%) were scheduled for removal in the initial treatment plan; but after CBCT, the decision was not to treat. If external root resorption involved the pulp of the second molar, there was an almost 17 times higher risk that this tooth was removed instead of the third molar (logistic regression analysis: odds ratio 16.8; p < 0.001). CONCLUSIONS: Findings in CBCT often changed the treatment plan. Severe external root resorption observed in CBCT was the main decisive factor for removing the second instead of the third molar.

Migration of the root complex after coronectomy occurs within the first year after surgery: a 5-year radiographic analysis and protocol suggestion.

OBJECTIVES: Currently, there are no studies evaluating the radiographic follow-up protocol after coronectomy. This study aims to assess root migration after coronectomy of mandibular third molars in panoramic images taken 1, 3 and 5 years after surgery. STUDY DESIGN: This was a prospective cohort study of patients undergoing coronectomy of a mandibular third molar. The patients followed a 5-year follow-up regimen with panoramic examinations at 1, 3 and 5 years after the surgical intervention. Three observers assessed the panoramic images in a blinded randomized order to evaluate bone coverage; superimposition of the roots and the mandibular canal; and migratory changes of the roots. Descriptive statistics were used to describe changes. Furthermore, reproducibility among the observers was calculated. RESULTS: Sixty-two patients were included. Ingrowth of bone superior to the root complex during the first year was registered by all observers (observer 1: 100%; observer 2: 77.4%; and observer 3: 85.5%). Superimposition of the mandibular canal and the root complex in the panoramic images taken in the immediate postoperative period and after 1 year showed that 53.2% to 62.9% went from superimposition to no superimposition. Interobserver reproducibility was high. CONCLUSIONS: Migration of the root complex occurs primarily within the first year after coronectomy. Therefore, a routine radiographic follow-up after 1 year only is recommended.

Marginal bone loss and resorption of second molars related to maxillary third molars in panoramic images compared with CBCT.

OBJECTIVES: Compare findings among observers in panoramic images (PAN) and cone beam CT (CBCT); and assess findings in PAN as indicators for marginal bone loss and resorption observed in CBCT. METHODS: 120 impacted maxillary third molars with PAN and CBCT were included. Four observers assessed morphological features: (1) tooth angulation; (2) number of roots; (3) bony impaction (yes/no) and pathology; (4) marginal bone level at the second molar (normal/>3 mm = bone loss); (5) resorption in the second molar (no/superficial/< half way through the dentin/≥ half way through the dentin/involving the pulp); (6) size of follicular space (normal/> 4 mm(cyst)). Percentage accordance and κ statistics described observer variation in PAN and CBCT. Logistic regression analyses tested findings in PAN as indicators for marginal bone loss or resorption observed in CBCT. RESULTS: κ values were fair and interobserver accordance was marginally higher in CBCT than PAN. Agreement between PAN and CBCT was 81-88% for marginal bone loss and 68-81% for resorption. Severe resorption was more often observed in CBCT. Mesio-angulated third molars and marginal bone loss interpreted in PAN significantly indicated marginal bone loss observed in CBCT (odds ration 17-34; p < 0.012; 8.8-52.8; p < 0.02). In contrast, findings in PAN were not significant indicators for resorption observed in CBCT (p > 0.05). CONCLUSION: In general, there was a fair agreement for marginal bone loss between PAN and CBCT, and PAN could significantly predict bone loss observed in CBCT. However, presence of resorption observed in CBCT could not be determined from PAN, and more severe resorption was observed in CBCT. CBCT is indicated if resorption in the second molar needs to be assessed.