Anne Caroline Costa Oenning

External Root Resorption of the Second Molar Associated With Third Molar Impaction: Comparison of Panoramic Radiography and Cone Beam Computed Tomography

PURPOSE The aim of the present study was to compare panoramic radiography and cone beam computed tomography (CBCT) for the assessment of external root resorption (ERR) of second molars associated with impacted third molars. In addition, the prevalence of ERR in second molars and the inclinations of the third molars more associated with ERR were investigated in both imaging methods. MATERIALS AND METHODS The sample consisted of 66 individuals with maxillary and mandibular impacted third molars (n = 188) seen on panoramic radiographs and CBCT images. The presence of ERR on the adjacent second molar was investigated, and the position of the third molar was determined using Winters classification (vertical, horizontal, mesioangular, distoangular, and transverse). Statistical analysis was performed using the χ(2) test, Fisher exact test, and 2-proportion Z test (the significance level was set at 5%). RESULTS A significantly greater number of cases of ERR (P < .0001) was diagnosed from CBCT images (n = 43, 22.88%) than panoramic radiographs (n = 10, 5.31%). The agreement between the panoramic radiographs and CBCT scans for diagnosing ERR was 4.3%. Mandibular third molars in mesioangular and horizontal inclinations were more likely to cause resorption of the adjacent teeth. CONCLUSIONS CBCT should be indicated for the diagnosis of ERR in second molars when direct contact between the mandibular second and third molars has been observed on panoramic radiographs, especially in mesioangular or horizontal impactions. Furthermore, considering the propensity of these teeth to cause ERR in second molars, third molar prophylactic extraction could be suggested.

Mesial Inclination of Impacted Third Molars and Its Propensity to Stimulate External Root Resorption in Second Molars—A Cone-Beam Computed Tomographic Evaluation

PURPOSE To investigate the presence of external root resorption (ERR) in second molars adjacent to horizontally and mesioangular impacted mandibular third molars by cone-beam computed tomography. In addition, patient characteristics (age and gender) and third molar depth were correlated with the presence of ERR. MATERIALS AND METHODS The sample consisted of 116 scans (58 acquired on the i-CAT Classic and 58 on the Picasso-Trio) of 70 women and 46 men (mean age, 23.7 yr). Two observers recorded the presence of ERR in the second molars, inclination and depth of third molars in relation to bone and soft tissues, third molars classification according to Pell and Gregory, and location and severity of ERR. Data were analyzed by analysis of variance, Mann-Whitney test, and χ(2) test. The κ test was used to analyze intraobserver agreement. RESULTS The overall prevalence of ERR was 49.43%. There were no statistically significant differences in the detection of ERR by gender, images from the 2 devices, or third molar inclination (P > .05). The κ test showed excellent reproducibility values (κ = 0.7778). There was a smaller proportion of affected patients 14 to 24 years old and ERR in teeth adjacent to Class C third molars. CONCLUSION Mesially inclined third molars (mesioangular and horizontal) have a greater potential of being associated with ERR in second molars, which was shown by the high prevalence of the condition in the overall sample. Class A and B third molars in patients older than 24 years were more associated with the presence of ERR in adjacent teeth.

Usefulness of cone‐beam CT in the evaluation of a spontaneously healed root fracture case

Horizontal root fractures (HRF) usually affect anterior teeth of male patients as a result of trauma. The consequences can be complex because of combined damage to different tissues, but it has been reported that root fractures undergo healing in majority cases. Diagnosis of HRF must be based on clinical findings, sensibility tests, and radiographic examination. The cone-beam computed tomography (CBCT) has already been proven to be superior among other radiographic modalities for diagnostic imaging of root fractures. However, CBCT in these cases needs to be used in a careful manner, and only when the radiation exposure should be justified by the potential diagnostic benefits and improvement of the treatment results. This case report describes a case of spontaneously healed horizontal root fracture with displacement of the fragments and discusses the usefulness of CBCT in the follow-up of root fractures cases.

Comparison of panoramic radiography and cone beam CT in the assessment of juxta-apical radiolucency

OBJECTIVES To compare the performance of panoramic radiography (PAN) and cone beam CT (CBCT) in the detection of juxta-apical radiolucency (JAR), as well as to investigate, in CBCT images, if there are factors associated with the detection of JAR on PAN. METHODS Two oral radiologists assessed the presence of JAR in PAN and CBCT images of 175 individuals (308 mandibular third molars). The cortical plates involvement and the JAR size and location were assessed on CBCT to evaluate if these factors were related to JAR detection on PAN. McNemars test and multiple logistic regression were performed. RESULTS PAN and CBCT differed significantly in the detection of JAR (p = 0.001). On PAN, JAR was identified on 24% of the patients while on CBCT its detection increased to 32.6%. JAR was detected only on CBCT and only on PAN in 26 and 7 cases, respectively. Distal/mesial surfaces of dental roots were where JAR was mostly located (84.5%), cortical thinning was found in 59.2% of cases and the mean (SD) of JAR size was 5.03 (±1.8) mm. However, these factors were not associated with JAR detection on PAN (p > 0.05). On the other hand, the location of the cortical involvement (if buccal or lingual) was associated with JAR detection on PAN, which was more detectable when the thinning was on buccal cortical. CONCLUSIONS Juxta-apical radiolucency is more often detected on CBCT than on PAN. JAR detection on PAN was improved when it was related to the buccal cortical plate of the mandible.

DIMITRA pediatric skull phantoms: development of age-specific pediatric models for dentomaxillofacial radiology research

OBJECTIVES This report aims to describe the development of age-specific phantoms for use in paediatric dentomaxillofacial radiology research. These phantoms are denoted DIMITRA paediatric skull phantoms as these have been primarily developed and validated for the DIMITRA European research project (Dentomaxillofacial paediatric imaging: an investigation towards low-dose radiation induced risks). METHODS To create the DIMITRA paediatric phantoms, six human paediatric skulls with estimated ages ranging between 4 and 10 years- old were selected, protected with non-radiopaque tape and immersed in melted Mix-D soft tissue equivalent material, by means of a careful procedure (layer-by-layer). Mandibles were immersed separately and a Mix-D tongue model was also created. For validation purposes, the resulting paediatric phantoms were scanned using a cone-beam CT unit with different exposure parameter settings. RESULTS Preliminary images deriving from all scans were evaluated by two dentomaxillofacial radiologists, to check for air bubbles, artefacts and inhomogeneities of the Mix-D and a potential effect on the visualization of the jaw bone. Only skulls presenting perfect alignment of Mix-D surrounding the bone surfaces with adequate and realistic soft tissue thickness density were accepted. CONCLUSIONS The DIMITRA anthropomorphic phantoms can yield clinically equivalent images for optimization studies in dentomaxillofacial research. In addition, the layer-by-layer technique proved to be practical and reproducible, as long as recommendations are carefully followed.

Juxta-apical radiolucency: Prevalence, characterization and association with the third molar status

PURPOSE This study aimed to investigate the prevalence of juxta-apical radiolucency (JAR), assessing its association with third molar status and describing its radiologic features through panoramic radiography. MATERIALS AND METHODS We evaluated 1,050 radiographs (1,830 third molars) for the presence of JAR. The JAR and control groups were classified according to the third molars angulation, impaction, and root development. The presence of radiographic signs of proximity between the mandibular canal and third molar and the imaging features of JAR also were recorded. RESULTS JAR was identified in 116 patients (11%) and 130 third molars (7.1%), being significantly associated with female patients and with the second and third decades of life. There also was an association with teeth with a vertical angulation and complete root formation. Radiographic signs of proximity to the mandibular canal were absent in 66.2% of JAR cases. In most cases, there was lamina dura in the juxta-apical area that appeared to overlap the mandibular canal and to have a cortical outline. CONCLUSIONS JAR is not a rare imaging finding. Given its possible relationship with nerve injuries and its differential diagnostic possibilities, knowing the characteristics of JAR is important to assist professionals in treatment planning and making the correct diagnosis.

Temporomandibular joint disk adhesion: evidence from magnetic resonance images

This case report has the aim to present an adhesion of the temporomadibular disc to the articular eminence, diagnosed on magnetic resonance imaging images. A 37-year-old female patient with TMJ (temporomandibular joint) disk adhesion on the left side and complaining of bilateral otalgia over the last 2 years is reported in the present article. The patient did not complain of articular pain or clicking, or any other noises of any nature. Clinical observation showed that the patient had restricted jaw opening, with mandibular deviation the left side without correction during mandibular movement. Our diagnostic impression was of partial anterior disk displacement with reduction of the right side disc; and partial anterior disk displacement with reduction and disc disk adhesion with hypo-mobility of the condyle, on the left temporomandibular joint. The peculiarity of this reported case is the fact that besides the bilateral partial anterior disc displacement, there was also found an adhesion of the disc on the left side. In conclusion, the magnetic resonance imaging exam of the temporomandibular joint can be considered an exam of choice for the evaluation of disc positioning and its morphological alterations.

Irradiation provided by dental radiological procedures in a pediatric population

BACKGROUND Children are more sensitive to ionizing radiation effects due to their high radiosensitivity. PURPOSE To estimate doses and risks for dental radiological examinations in children. MATERIAL AND METHODS A pediatric population consisting of 7150 children and young adults which underwent 12252 dental radiological examinations (4220 intraoral, 1324 cephalometric, 5284 panoramic radiographs and 1424 CBCTs) within two years were included. Two groups were studied: CBCT group (exposed to CBCT ± conventional radiographs) and 2D group (exposed only to 2D radiological examinations). The effective doses were corrected according to age at exposure and settings parameters (mA;FOV) by using logarithmic fit equations for dose interpolation. The individual cumulative dose, per-caput collective dose and radiation risk were calculated for each group. RESULTS The median effective and cumulative doses for conventional radiographs were lower than 20 μSv and did not vary with age. Children exposed to CBCT had a higher median effective dose (127.2 μSv) and cumulative dose (156.5 μSv) with a significant increased cumulative dose between 11 and 14 years. The CBCT contributed with 70% to the collective dose and per caput collective dose was 184 μSv for CBCT exposures. The Life Attributable Risk (LAR) and Relative Radiation Level (RRL) were significantly higher for children exposed to CBCT under the age of 18. The highest radiation dose for CBCT was equivalent with 34.1 days of natural background radiation and it was found for ages between 11 and 15. CONCLUSION The CBCT doses and radiation risk vary but remain in the lower levels of the relative risk of medical exposures.

Resorptive potential of impacted mandibular third molars: 3D simulation by finite element analysis

ObjectivesPrevious studies have suggested a relationship between resorption in second molars and pressure from the eruptive force of the third molar. The aim of this study was to simulate functional forces in a mandible model by means of finite element analysis and then assess the biomechanical response produced by impacted third molars on the roots of the second molar.Materials and methodsA cone beam computed tomography scan presenting an impacted mandibular third molar was segmented (Mimics V17 software). The modeling process was performed using the reverse engineering technique provided by the Rhinoceros 3D 5.0 software. The third molar position was changed in order to produce different inclinations of the impacted tooth. Bite forces were simulated to evaluate total deformation, the equivalent von Mises stress, minimum principal stress on hard tissue, and equivalent elastic strain on soft tissue.ResultsAreas of high energy dissipation and compression stress were detected in the second molar root, independently of the inclination of the impacted third molar. In general, the horizontal position was the situation in which major stress and the amount of deformation occurred in the second and third molar regions.ConclusionImpacted third molars in close proximity with the adjacent tooth can generate areas of compression concentrated at the site of contact, which suggests an involvement of mechanical factors in the triggering of resorption lesions.Clinical relevanceThe results of these computational experiments contribute to the understanding of the triggering and progression of resorptive lesions in the adjacent second molar.