Efficacy of CBCT for assessment of impacted mandibular third molars: a review - based on a hierarchical model of evidence

Investigation of the relationship between the mandibular third molar teeth and the inferior alveolar nerve using posteroanterior radiographs: a pilot study

BACKGROUND

The most severe complication that can occur after mandibular third molar (MM3) surgery is inferior alveolar nerve (IAN) damage. It is crucial to have a comprehensive radiographic evaluation to reduce the possibility of nerve damage. The objective of this study is to assess the diagnostic accuracy of panoramic radiographs (PR) and posteroanterior (PA) radiographs in identifying the association between impacted MM3 roots and IAN.

METHODS

This study included individuals who had PR, PA radiographs, and cone beam computed tomography (CBCT) and who had at least one impacted MM3. A total of 141 impacted MM3s were evaluated on CBCT images, and the findings were considered gold standard. The relationship between impacted MM3 roots and IAN was also evaluated on PR and PA radiographies. The data was analyzed using the McNemar and Chi-squared tests. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy of PR and PA radiographies were determined.

RESULTS

Considering CBCT the gold standard, the relationship between MM3 roots and IAN was found to be statistically significant between PR and CBCT (p = 0.00). However, there was no statistically significant relationship between PA radiography and CBCT (0.227). The study revealed that the most prevalent limitation of the PR in assessing the relationship between MM3 roots and IAN was the identification of false-positive relationship.

CONCLUSIONS

PA radiography may be a good alternative in developing countries to find out if there is a contact between MM3 roots and IAN because it is easier to get to, cheaper, and uses less radiation.

Distribution and impaction patterns of third molars in a sample of German population: Retrospective analysis in a high turnover maxillofacial department

BACKGROUND

The surgical removal of impacted third molars is considered a routine procedure for oral and maxillofacial surgeons. However, the distribution of impacted molars varies among different populations. A study into impaction patterns in the German population is currently not described. The aim of this retrospective study is to determine patterns of impacted third molars in a sample of German population, to identify gender and age specific differences as well as further risk factors for impacted molar extraction and to compare these results with other studies.

MATERIALS AND METHODS

The clinical findings and digital panoramic radiographs of 84 patients with a total of 243 impacted third molars that had been subjected for tooth extraction, from January to September 2023, were collected and analyzed. All third molars were analyzed according to Winter´s angulation, Pell and Gregory Score of depth and relationship to ramus. Furthermore, inferior alveolar nerve and maxillary sinus proximity were identified through a newly developed risk score and an analysis of patient´s gender and age regarding impaction patterns was performed.

RESULTS

No significant gender specific differences were found regarding the impaction patterns. Third molar angulations significantly differed regarding patient´s age (cut-off 26 years). In comparison, third molar depth, bone coverage, nerve approximity and angulation patterns differed from the results of other populations.

CONCLUSION

The results of this study can serve as a baseline for further studies of third molar impactions in the German population to minimize perioperative complications in impacted third molar surgery.

Dental-dedicated MRI, a novel approach for dentomaxillofacial diagnostic imaging: technical specifications and feasibility

MRI is a noninvasive, ionizing radiation-free imaging modality that has become an indispensable medical diagnostic method. The literature suggests MRI as a potential diagnostic modality in dentomaxillofacial radiology. However, current MRI equipment is designed for medical imaging (eg, brain and body imaging), with general-purpose use in radiology. Hence, it appears expensive for dentists to purchase and maintain, besides being complex to operate. In recent years, MRI has entered some areas of dentistry and has reached a point in which it can be provided following a tailored approach. This technical report introduces a dental-dedicated MRI (ddMRI) system, describing how MRI can be adapted to fit dentomaxillofacial radiology through the appropriate choice of field strength, dental radiofrequency surface coil, and pulse sequences. Also, this technical report illustrates the possible application and feasibility of the suggested ddMRI system in some relevant diagnostic tasks in dentistry. Based on the presented cases, it is fair to consider the suggested ddMRI system as a feasible approach to introducing MRI to dentists and dentomaxillofacial radiology specialists. Further studies are needed to clarify the diagnostic accuracy of ddMRI considering the various diagnostic tasks relevant to the practice of dentistry.

Relationship between Impacted Mandibular Third Molars and the Mandibular Canal on CBCT Scans

This study aimed to assess the relationship of impacted mandibular third molars with the mandibular canal on cone beam computed tomography (CBCT) scans. This cross-sectional study was conducted on CBCT scans of 137 patients with 204 impacted mandibular third molars. The relation of age, gender, class of impaction, anatomical position of canal relative to tooth (buccal, lingual, inferior, inter-radicular), tooth angulation (mesioangular, vertical, distoangular, horizontal), relationship of tooth with the mandibular canal (no contact, in contact, relation), relationship of tooth with the mandibular cortex, anatomical site of contact of tooth with the mandibular cortex (buccal, lingual, inferior), and the impression of canal (grooving, no effect) on impacted teeth were evaluated. Data were analyzed using one-way ANOVA, Chi-square test and Fisher's exact test. Class B of impaction (78.9%), inferior position of canal relative to the impacted tooth (53.9%) and mesioangular angulation (53.4%) had the highest frequency, respectively. The relationship of tooth with the mandibular canal was "relation" in most cases (53.4%) followed by no contact (26.9%) and in contact (19.6%). Significant associations were noted between depth of impaction (P < 0.001), tooth angulation (P = 0.024), anatomical position of canal relative to tooth (P < 0.001), relationship of tooth with the mandibular cortex (P = 0.032) and anatomical site of contact of tooth with the mandibular cortex (P = 0.013) with the impacted tooth-mandibular canal relationship. CBCT provides accurate information about the relationship of impacted third molars with the mandibular canal and can decrease the risk of traumatization of inferior alveolar nerve (IAN) during their surgical extraction.

Pathologic conditions associated with impacted third molars: A retrospective study of panoramic radiographs in a Southern Brazilian population

Purpose

This study investigated the prevalence of developmental and acquired pathologic conditions associated with impacted third molars (3Ms) in a Southern Brazilian population and evaluated whether demographic and tooth characteristics were correlated with the presence of bone or tooth lesions.

Materials and Methods

Panoramic radiographs were assessed for developmental (bone-related) or acquired (tooth-related) pathoses associated with impacted upper or lower 3Ms. Data on tooth positioning, tooth development, and patient demographics were collected. A trained, calibrated postgraduate student evaluated all images. Binary and multivariate logistic regression models were used to assess associations between outcomes and the demographic and radiographic variables. The threshold for statistical significance was set at 5% (P<0.05).

Results

The sample comprised panoramic radiographs from 2054 patients, predominantly female (59.2%), with a mean age of 27.2 ± 11.5 years. Overall, 4066 impacted 3Ms were evaluated, revealing 471 (11.6%) developmental and 710 (17.5%) acquired pathoses. Among the developmental pathoses, 460 (95.2%) were indicative of dentigerous cysts. Male sex, lower 3M location, vertical or distoangular positioning, and incomplete root formation were associated with an elevated likelihood of developmental pathology. Lower tooth position, complete root formation, and partial eruption were linked to an increased probability of an acquired pathology in the third or second molar.

Conclusion

The prevalence of pathologic conditions associated with impacted 3Ms was low. Male sex, lower 3M placement, horizontal or distoangular positioning, and incomplete root formation were associated with developmental pathoses, while lower tooth position, complete root formation, and partial eruption were related to acquired pathoses.

Radiographic evaluation of mandibular third molars: an ex vivo comparative study between multilayer and conventional panoramic radiography

OBJECTIVES

To compare the multilayer panoramic radiography (MPAN) and conventional panoramic radiography (CPAN) in the evaluation of mandibular third molars using cone-beam computed tomography (CBCT) as a reference.

METHODS

CPAN, MPAN, and CBCT scans from 33 dry human mandibles were acquired using the OP300 Maxio unit, totalizing 56 mandibular third molars to be evaluated. Three examiners evaluated each third molar according to their position, depth of impaction in the mandibular ramus, proximity between the dental root apexes and the mandibular canal, and the presence of radiographic signs of proximity to the mandibular canal. In addition, when there was a distance between the root apexes and the mandibular canal, it was measured. As a reference, these same parameters were assessed in the CBCT scans by a fourth examiner. For the statistical analysis, the weighted Kappa, Bland Altman, and Wilcoxon tests were performed (α = 0.05).

RESULTS

The agreement between the assessments performed in the panoramic modalities with the CBCT ranged from 66.1% to 100.0% for the categorical variables. Overall, the agreement values of CPAN and MPAN with CBCT were similar. The distances between the dental root apex and the mandibular canal for both CPAN and MPAN were significantly underestimated compared to CBCT (p < 0.05). The intra- and interexaminer agreements of the examiners ranged from poor to almost perfect; in general, the agreements were higher in the evaluation performed in the MPAN than in the CPAN.

CONCLUSIONS

The MPAN performs similarly to CPAN for evaluating mandibular third molars and their proximity relationship to the mandibular canal.

CLINICAL RELEVANCE

Preoperative evaluation of lower mandibular third molars is usually performed using CPAN. Recently, a new tool, MPAN, was developed, which has not yet been tested for the evaluation of mandibular third molars and showed similar performance to CPAN in the present study. Future studies using MPAN are encouraged to evaluate other diagnostic tasks.

Automatic classification of 3D positional relationship between mandibular third molar and inferior alveolar canal using a distance-aware network

The purpose of this study was to automatically classify the three-dimensional (3D) positional relationship between an impacted mandibular third molar (M3) and the inferior alveolar canal (MC) using a distance-aware network in cone-beam CT (CBCT) images. We developed a network consisting of cascaded stages of segmentation and classification for the buccal-lingual relationship between the M3 and the MC. The M3 and the MC were simultaneously segmented using Dense121 U-Net in the segmentation stage, and their buccal-lingual relationship was automatically classified using a 3D distance-aware network with the multichannel inputs of the original CBCT image and the signed distance map (SDM) generated from the segmentation in the classification stage. The Dense121 U-Net achieved the highest average precision of 0.87, 0.96, and 0.94 in the segmentation of the M3, the MC, and both together, respectively. The 3D distance-aware classification network of the Dense121 U-Net with the input of both the CBCT image and the SDM showed the highest performance of accuracy, sensitivity, specificity, and area under the receiver operating characteristic curve, each of which had a value of 1.00. The SDM generated from the segmentation mask significantly contributed to increasing the accuracy of the classification network. The proposed distance-aware network demonstrated high accuracy in the automatic classification of the 3D positional relationship between the M3 and the MC by learning anatomical and geometrical information from the CBCT images.

Cone-beam computed tomography-based radiographic considerations in impacted lower third molars: Think outside the box

Purpose

This study aimed to evaluate the anatomic circle around the impacted lower third molar to show, document, and correlate essential findings that should be included in the routine radiographic assessment protocol as clinically meaningful factors in overall case evaluation and treatment planning.

Materials and Methods

Cone-beam computed tomographic images of impacted lower third molars were selected according to specific inclusion criteria. Impacted teeth were classified according to their position before assessment. The adjacent second molars were assessed for distal caries, distal bone loss, and root resorption. The fourth finding was the presence of a retromolar canal distal to the impaction. Communication with the dentist responsible for each case was done to determine whether these findings were detected or undetected by them before communication.

Results

Statistically significant correlations were found between impaction position, distal bone loss, and detected distal caries associated with the adjacent second molar. The greatest percentage of undetected findings was found in the evaluation of distal bone status, followed by missed detection of the retromolar canal.

Conclusion

The radiographic assessment protocol for impacted third molars should consider a step-by-step evaluation for second molars, and clinicians should be aware of the high prevalence of second molar affection in horizontal and mesioangular impactions. They also should search for the retromolar canal due to its associated clinical considerations.

Orthodontic treatment of substituting third molars for missing permanent molars

INTRODUCTION

This study aimed to evaluate the orthodontic effect and efficiency of substituting third molars for missing first or second permanent molars systematically.

METHODS

Forty-six patients (69 third molars total) with missing permanent molars replaced by third molars were selected. The angulation, crown-to-root ratio, and periodontal condition of the third molars before and after treatment were compared. The American Board of Orthodontics Objective Grading System was used to evaluate the alignment and occlusion of third molars after treatment. The duration of orthodontic treatment and third molar replacement therapy were also recorded.

RESULTS

The average orthodontic treatment time was 33.9 ± 5.6 months, and the average angulation change of third molars during treatment was 49.8 ± 29.8°. The average height of mesial alveolar bone increased by 4.8 ± 0.5 mm in patients whose third molars were mesially inclined or horizontally impacted. The root length of adult patients decreased by 0.72 ± 0.02 mm on average, and the average gingival recession was 0.10 mm, both of which were not statistically significant. The average score for each third molar evaluated by the American Board of Orthodontics Objective Grading System was 1.8 ± 0.5 points.

CONCLUSIONS

If the indications and timing of treatment were well-controlled, third molars would be excellent substitutes for missing first or second permanent molars through the orthodontic method.

Assessment of Bone Height Changes Based on the Cone-Beam Computed Tomography Following Intentional Replantation for Periodontally Compromised Teeth

Background and Objectives; This study aimed to evaluate the clinical outcomes and bone changes before and after intentional replantation (IR) for periodontally compromised teeth by using cone-beam computed tomography (CBCT). Materials and Methods; Fourteen periodontally involved teeth were selected for IR. A preoperative orthodontic procedure was performed to apply luxation, and the tooth was then gently extracted. Retrograde filling of the root-end canal was performed. Once the tooth was repositioned in the socket, it was splinted with the adjacent tooth. After three months, prosthetic restoration was performed. Results; Clinical parameters and CBCT images were obtained before and after the IR procedure. The height of the alveolar bone was measured on the CBCT images by using software. Most preoperative symptoms, including pain, mobility, probing depth (PD) and bleeding on probing (BOP), significantly decreased after IR (pain: 4.71 to 1.00; mobility: 1.36 to 0.29; PD: 5.60 to 2.85; BOP: 3.50 to 0.79). CBCT analysis indicated an increase in bone height after IR (the amount of change: maxilla, 4.00; mandible, 1.95). Conclusions; A previous study reported that IR for periodontally involved teeth is quite limited. However, in this study, IR of periodontally compromised teeth showed favorable results in clinical and radiographic evaluations, suggesting that IR may be an alternative to extraction of teeth with periodontal disease.

Can lower third molar position indicate the need for preoperative cone beam computed tomography exploration of retromolar canal?

OBJECTIVES

This study aims to reveal whether and which position of lower third molar (M3), assessed on a 2D image, indicates or potentially exclude the need for the CBCT exploration of the retromolar canal (RMC). We hypothesized that some positions of M3 are associated with overall higher incidence of the RMC, and particularly clinically relevant ones, thus justifying additional CBCT diagnostics.

METHODS

CBCT exam of 186 hemi-mandibles with present M3 were selected for the study. Explorations were made during the 2-year period from January 1th 2018 to December 31th 2019 with Scanora 3Dx Sorodex (Tussula, Finland). The following variables were assessed: the presence and width of the RMC, eruption status, and angulation of the M3. The RMC presence in relation to the M3 eruption status and angulation was analyzed using appropriate statistical tests.

RESULTS

RMC was present in 89 (47.8%) out of 186 hemi-mandibles. Mean canal width was 1.51 mm. 22.5% of detected canals had the diameter exceeding 2 mm. Third molar's eruption status showed no statistical correlation with the occurrence of RMC. We observed significantly higher occurrence of RMC in the hemi-mandibles containing distally angulated M3 in comparison to other orientations (p = 0.025).

CONCLUSION

Based upon our findings, we recommend preoperative CBCT in cases where distal angulation of M3 is observed on 2D images, for the purpose of RMC exploration. Lower resolution CBCT mode and limited field of view (XS or S) are sufficient for the visualization of potentially clinically relevant RMCs, with as much reducing the patient dose.

Diagnostic value of routine dental radiographs for predicting the mandibular canal localization validated by cone-beam computed tomogram measurements

OBJECTIVES

To test the hypothesis that routine dental radiographs can be used to draw conclusions regarding the mandibular canal (MC) localization. MATERIAL AND METHODS: A total of 108 radiographs (36 orthopantomograms [OPTs], 36 lateral cephalograms [LCs], and 36 cone-beam computed tomograms [CBCTs]) of 36 patients were analyzed. Statistical analysis included all cephalometric parameters obtained by OPTs, LCs, and CBCTs. Potential influencing parameters were calculated using linear and logistic regression with a backward removal algorithm. For predictability of MC localization, parameters were correlated using Pearson's correlation.

RESULTS

The MC ran along the lingual half (n = 24) twice as often as in the buccal half (n = 12) in the population studied. The position was always symmetrical contralaterally. No sex-specific influence was observed (p = .34). Lingual and buccal MC courses were statistically significantly correlated to increased and decreased jaw angles (LC/OPT), respectively (p = .003; r = -.48/p = .010; r = -.42). An increased jaw angle was significantly correlated with a more cranial MC position (p = .013; r = -.41); a deep and distal bite position was significantly correlated with a caudal and buccal MC position (p = .004; r = -.47/p = .001; r = .57). Moreover, an increase of 1 point in the Hasund score predicted an increased probability of a buccal MC position by 18.6%. The jaw angle analyzed in OPT and LC images were positively correlated (r = .89, p < .001).

CONCLUSIONS

Routine dental radiographs provide informative guidance on the location of the MC in the vertical and transverse levels. This finding could be used in the initial consultation and treatment planning to consider more invasive diagnostic methods further down the line.

Cone-Beam Computed Tomography and the Related Scientific Evidence

Cone-beam computed tomography (CBCT) is the most common three-dimensional (3D) imaging technique used in dentistry [...]

Can CBCT change the level of confidence of oral maxillofacial surgeons in mandibular third molar management?

This study analyzed the impact of CBCT on the level of confidence in diagnostic and treatment thinking in mandibular lower molar (M3M) clinical management. Thirty cases for which panoramic radiographs and CBTC images were available were selected and classified according to radiologic signs indicating the proximity of the M3M to the mandibular canal (interruption of the radiopaque borders of the canal of the mandibular canal wall, darkening of the roots, and diversion or narrowing of the canal, n = 10 for each classification). Twelve oral and maxillofacial surgeons (OMS) contributed to this study by answering two questionnaires. The first questionnaire contained a clinical description of the case and a panoramic radiograph. After 30 days, a second questionnaire with the same clinical illustrations and tomographic multiplanar reconstruction images was administered. Both questionnaires asked specialists to rate diagnostic confidence, the surgical complexity, chosen treatment, and surgical confidence. In approximately 40% of answers, CBCT images had a positive impact on ratings of diagnostic confidence and treatment thinking confidence, and in 24.4%, they increased the surgical complexity score. There was no change in the treatment plan following the use of CBCT, but the CBCT examination was a determining factor for diagnosis and treatment planning in 72.8% of the answers CBCT improved the confidence level in diagnostic and treatment thinking of the M3M management while also increasing the perceived level of surgical complexity. The findings of this study support the need to consider using CBCT in diagnosis and treatment planning for M3Ms with radiographic signs such as darkening of the roots, interruption of the radiopaque borders of the mandibular canal, or deviation of the mandibular canal and narrowing of the roots.

Correlation of Pericoronal Radiolucency Around Impacted Mandibular Third Molars Using CBCT with Histopathological Diagnosis: A Prospective Study

Purpose:

This study aimed to correlate the pericoronal width surrounding impacted mandibular third molars with their histopathological findings.

Materials and Methods:

The present study included patients who were advised for extraction of impacted mandibular third molars with the pericoronal radiolucency radiographically. The CBCT scans were compared with histopathologic findings of the follicles.

Results:

Out of 70 patients evaluated histopathologically, 24 patients showed mild inflammatory changes, whereas 34 patients revealed cystic changes suggestive of a dentigerous cyst, followed by 12 patients showing evidence of calcifications in the pericoronal follicles. The dentigerous cyst was more likely to occur if the bucco-lingual width of the pericoronal radiolucency was 14.00-16.00mm, and calcifications were found to be most likely present if the buccolingual width was 12.00-14.00mm, both of which were statistically significant.

Conclusion:

CBCT can be a reliable tool in the evaluation of pericoronal follicular space, and the values in different dimensions can be an accurate predictor radiologically for the diagnosis of pathologies when compared to 2D imaging.

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.

Comparison of CBCT and panoramic radiography for the assessment of bone loss and root resorption on the second molar associated with third molar impaction: a systematic review

OBJECTIVE

To investigate whether the use of cone beam CT (CBCT) changes the diagnosis of external root resorption (ERR) or marginal bone loss (MBL) involving a second molar adjacent to an impacted third molar.

METHODS

A systematic search was applied in PubMed, EMBASE, Scopus, Web of Science, LILACS, Google Scholar, OpenGrey, and ProQuest. Studies assessing the detection of ERR or MBL in a second molar adjacent to an impacted third molar through CBCT and panoramic radiography (PAN) were included. Prevalence and agreement between PAN and CBCT on the detection of ERR and MBL were collected. The risk of bias was assessed using the MAStARI.

RESULTS

A total of 593 papers were identified, and after a 2-phase selection, 5 studies were included in the narrative synthesis. Regarding ERR, its prevalence in PAN was reported from 5.31 to 19.5% and from 22.8 to 62.0% in CBCT. The percentage of agreement varied from 28.5 to 74.0%. The prevalence of MBL varied from 21.9 to 62.9% in PAN, while those values varied from 21.6 to 80% in CBCT images. The percentage of agreement between PAN and CBCT for the detection of MBL ranged from 66.0 to 85.0%. Four studies presented low risk of bias and one had moderate risk.

CONCLUSIONS

More ERR and MBL are assessed in CBCT compared to PAN. There is a considerable agreement between PAN and CBCT assessment of ERR and MBL, however, mostly related to the absence of the pathology rather its presence.

Compression of the Inferior Alveolar Canal by Mandibular Third Molar among Images Taken from Patients Visiting Dental Imaging Centres of Kathmandu: A Descriptive Cross-sectional Study

INTRODUCTION

Third molars are common teeth to be impacted. The position of mandibular third molar is such that it is in close contact with inferior alveolar canal which may lead to nerve damage during its removal. So, this study was conducted to find out the prevalence of compression of inferior alveolar canal by mandibular third molars.

METHODS

This descriptive cross-sectional study was conducted on images collected from Dental Imaging Centers of Nepal from 25th June 2020 to 15th February 2021 after obtaining ethical clearance from Nepal Health Research Council (Reference number: 2100). A convenience sampling method was used to collect 433 cone-beam computed tomography images showing the relation between the third molars and inferior alveolar canal. Data were analyzed using the Statistical Package for the Social Sciences version 16. Point estimate at 95% confidence interval was calculated along with frequency and proportion for the binary data.

RESULTS

Out of 433 images, 135 (31.17%) (26.80-35.53 at 95% Confidence Interval) images showed compression of inferior alveolar nerve by mandibular third molar. The study result indicated that 16 (11.85%) buccally placed, 50 (37.03%) lingually placed and 69 (51.11%) inferiorly placed inferior alveolar canal were compressed by apices of mandibular third molars.

CONCLUSIONS

The prevalence of compression of inferior alveolar canal by mandibular third molar was found to be similar to other studies done in similar settings. Compression of the canal was more evident when inferior alveolar canal is situated lingually.

Prediction of neurosensory disorders after impacted third molar extraction based on cone beam CT Maglione's classification: A pilot study

Background

Surgical difficulty assessment in the extraction of impacted mandibular third molars is a constant challenge for oral surgeons.

Aim

The first aim was to apply Maglione's new classification on patients that needed surgical extraction of impacted mandibular third molars, and the second aim was to study the correlation of the classification classes with the occurrence of postoperative neurosensory disorders.

Materials & methods

The present prospective clinical trial pilot study was conducted on patients attending oral and maxillofacial surgery clinics from February 2017 until January 2018 for the surgical extraction of impacted lower third molars.

Results

Fifty-one out of sixty-nine patients made the surgical removal of one impacted mandibular third molar. The most common subclass was 1B (24.6%), followed by subclass 3B (23.2%). Subclass 3A and 4B showed an equal distribution of (11.6%) each, and then subclass 2B (10%). The most significant subclass was 4B with (5.9%) neurosensory disturbance. None of the patients had a permanent disturbance.

Conclusion

Maglione's classification offers unique detailed description of the buccolingual relationship of MTM with IAC that could be used as a future reliable radiographic guide to reduce the risk of post-operative neurosensory disturbances after MTM surgical removal.

Radiographic imaging in relation to the mandibular third molar: a survey among oral surgeons in Sweden

Objectives

To query the experience of oral surgeons concerning referral routines and preferences for radiographic imaging modality before surgical removal of mandibular third molars and investigate factors that influence imaging modality preferences.

Materials and methods

Members of the Swedish Association of Oral and Maxillofacial Surgeons (n = 280) were invited to participate in a web-based digital survey concerning their experiences and use of three imaging modalities in pre-surgical assessment of mandibular third molar removal. The survey comprised multiple-choice questions and four cases depicted in images; respondents reported whether they would supplement the cases with other images and, if so, from which modality.

Results

The response rate was 64%. Panoramic radiographs were most commonly used in pre-surgical planning (response options: always or often), significant difference between professions (p = 0.039), and considered to facilitate treatment planning (87%), as was CBCT (82%); for 51%, CBCT reduced post-operative complications. Preferred modality for localizing the mandibular canal was fairly evenly distributed and for non-complex case, significant difference between subgroups of OMFS surgeons was found (p = 0.003) as to preference for intraoral radiographs.

Conclusions

A majority of respondents received a report within 2 weeks of their referral for CBCT and would read the report and view the images before surgery. Image modality preference differed depending on case complexity, with a greater perceived need for CBCT. Profession and practical experience affected choice.

Clinical relevance

Choice of imaging modality in mandibular third molar assessment is also important from dose delivery and social economy standpoints.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-021-04189-9.

Correlation of Panoramic Radiography, Cone-Beam Computed Tomography, and Three-Dimensional Printing in the Assessment of the Spatial Location of Impacted Mandibular Third Molars

The development of radiology, rapid prototyping techniques, and the increasingly common use of 3D printing in dentistry inspires the use of these techniques to improve diagnostic and therapeutic processes. This study aimed to conduct a retrospective comparative analysis of dental panoramic radiographs, cone-beam computed tomography, and 3D printing in preoperative assessment of the procedure’s difficulty. Thirty clinical cases with a high degree of difficulty were selected, and based on evaluation with CBCT, a virtual 3D model of the region of surgical procedure was created, which was then printed using a 3D printer. The comparative analysis included the linear measurements performed in dental panoramic radiographs, cone-beam computed tomography, and 3D models in a preoperative assessment of the degree of retention and difficulty of impacted mandibular third molars in the mandible. Linear measurements performed on dental panoramic radiographs were significantly lower than in cone-beam computed tomography and 3D models. No statistically significant differences were obtained in linear measurements between 3D models and cone-beam computed tomography images except for the measurement of the lingual lamina thickness; however, due to the insignificant differences in measurements, with a mean of only 80 µm, the elective procedure of removal of the impacted third molar in the mandible may be safe.

Does a preoperative cone beam CT reduce complication rates in the surgical removal of complex lower third molars? A retrospective study including 486 cases

BACKROUND

This study was designed to analyse the value of preoperative Cone Beam CTs (CBCT) prior to the surgical removal of complex lower third molars. Furthermore, the aim was to assess injuries to the inferior alveolar nerve (IAN) bundle and postoperative neurological disorders depending on the position of the lower third molar and the inferior alveolar nerve bundle.

METHODS

In this retrospective examination preoperative Cone Beam CTs and Orthopantomographs (OPT) of 324 patients were analysed concerning the location of the lower third molars in relation to the mandible and the inferior alveolar nerve bundle. Surgery protocols of all patients who underwent the surgical removal of at least one complex lower third molar were analysed concerning patient data, length of surgery, intraoperative haemorrhage, intraoperative exposure of the inferior alveolar nerve bundle, postoperative swelling and postoperative neurological disorders. The data was then compared to data from international studies.

RESULTS

In all 324 patients a permanent neurological damage was not found. Temporary neurological damage was recorded in 13 cases (2.6%). A caudal nerve position with no measurable distance to the root of the lower third molar was associated with the highest risk of a temporal neurological damage. A vestibular touching nerve route also correlated with postoperative sensitivity impairment. If a mesioangulation (Winter) or a Pell and Gregory Type IIIC appears in the OPT, risk of neurological damage is at its highest.

CONCLUSIONS

Three-dimensional radiographic imaging, in our patient group, does not significantly affect the risk for complications during the surgical removal of complex lower third molars. Therefore, it should only be utilized for risk assessment, especially in cases of symptom-free lower third molars. A preoperative orthopantomogram still can be accepted as standard for radiographic imaging. An intraoperative exposure of the IAN bundle does not necessarily predict simultaneous neurological damage. Exposure of the IAN bundle is no indication for a discontinuation of the surgery.

Current thinking in lower third molar surgery

The removal of lower third molar teeth is one of the most common surgical procedures performed worldwide, but many concepts in this surgery have been unclear and have engendered different opinions. This paper aims to review current thinking in certain pertinent aspects of this surgery to update the reader on the most current research and synthesise it to make clinical recommendations. Topics covered include preoperative imaging, timing of removal, flap design, lingual retraction, coronectomy, lingual split, closure techniques, and use of antibiotics, steroids, and drains.

The Pattern of Mandibular Third Molar Impaction and Assessment of Surgery Difficulty: A Retrospective Study of Radiographs in East Baltic Population

Classifications of impacted teeth allow defining the type and degree of retention, as well as assessing the degree of difficulty of the procedure. The aim of this study was to conduct retrospective analysis of the degree of retention and difficulty in the surgical removal of impacted mandibular third molars in the clinical material of the Department of Oral Surgery in 2013–2018. This study included 1585 dental panoramic radiographs of patients of the Department of Oral Surgery, who reported in 2013–2018, in order to perform surgical removal of the impacted mandibular third molar. Based on dental panoramic radiographs, the degree of retention was determined based on classifications according to Winter, according to Pell and Gregory, according to Tetsch and Wagner, and according to Asanami and Kasazaki. The difficulty of the procedure was also assessed based on the Pederson index. The most common types of lower wisdom tooth impaction are as follows: in Winter’s classification, mesial-angular impaction; in Tetsch and Wagner’s classification, oblique medial-angular impaction; in Pell and Gregory’s classification, impaction grade 2A; and in Asanami and Kasazaki’s classification, 3A and anterior inclination. In most cases of surgical removal of an impacted tooth, the anticipated difficulty of the procedure was rated as very difficult.

CBCT Radiological Features as Predictors of Nerve Injuries in Third Molar Extractions: Multicenter Prospective Study on a Northeastern Italian Population

Background: Neurological alterations are one of the main complications occurring after the third molar extractions. The aim of this prospective multicenter cohort study was to find out Cone Beam Computed Tomography (CBCT) features and distribution of neurological complications in patients undergoing lower third molar surgery and to determine the radiological and patient-related factors that could be correlated to the occurrence of inferior alveolar and lingual nerves injury. Material and Methods: 378 patients who underwent lower third molar extraction from March 2018 to March 2019 were included. Clinical and radiological data were collected. CBCT features were recorded following Maglione et al. classification. Symptoms and characteristics of patients who experienced neurological alterations were evaluated. Results: 193 patients needed a second-level radiological exam (CBCT). In these patients, the most common feature was Maglione class 3: a higher frequency of apical or buccal mandibular canals in direct contact with the tooth was observed. 3.17% of the patients developed a neurological complication. Maglione class 4, increased age, and operative time were all positively correlated with neurological alterations. Conclusions: while the buccal or apical position of the mandibular canal was the more common findings, the lingual position was found to have a higher correlation with a negative outcome. Age and operative time were also found to be risk factors for developing nerve injury in the considered population.

Reliability of Orthopantamogram in Lower Third Molar Surgery: Inter- and Intra-observer Agreement

Context:

The evaluation of relationship between the roots of impacted lower third molar (IL3M) and inferior alveolar nerve injury (IAN) with orthopantamogram (OPG) is mandatory before performing de-impaction surgery. An investigation is considered reliable if it can be reproduced by various examiners. Assessment of OPG is subjective and varies among examiners. OPG is reliable to clinicians if the interpretation is not a product of guess work.

Aim:

The aim of this study was to evaluate the magnitude of agreement among oral surgeons and oral radiologist in observing intimate relationship between IL3M and mandibular canal.

Materials and Methods:

OPGs were evaluated by two oral surgeons and one oral radiologist for nerve root relationship. All the three were from different institutions with 10–15 years of experience. The three observers were blinded from each other’s findings. A total of 127 OPGs were evaluated for inter-observer agreement. Fifty OPGs were evaluated after 60 days for intra-observer agreement.

The agreement was evaluated based on Cohen’s κ statistics.

Results:

Our results denote that the interpretation of OPG among specialists is not in good agreement. We suggest development of methods to standardize evaluation of OPG and the exposure technique to improve inter-observer agreement among the dental specialists.

Evaluation of Mandibular Third Molar Region in a Turkish Population Using Cone-Beam Computed Tomography

OBJECTIVES

To evaluate impacted mandibular third molar tooth region and obtain linear measurements using CBCT images and to assess the relationship between the impacted third molar and the mandibular canal.

METHODS

CBCT scans of 351 patients (208 females, 143 males) were assessed. Age, gender, and impaction site were recorded for each patient. The relationship of third molars with the vertical axis of second molars, 2nd molar resorption and the relationship between third molar apices and the mandibular canal were assessed. In addition, the distance between ramus and second molar, mesiodistal width of the third molar, the angle between third molar and second molar, and width of the third molar capsule were measured. Binary Logistic Regression, Chi-Square Test, and General Linear Model were used for statistical analysis.

RESULTS

The highest percentage of impaction was found for mesioangular followed by transversal and vertical. The transversal impacted third molars revealed a significant association with adjacent second molar root resorption (p<0.001). There was a statistical significance between the second molar resorption and distance between ramus and second molar (p<0.001). The mesioangular impacted third molars revealed significant relation with the mandibular canal (p<0.05). The most frequent variation found was the dental canal followed by the retromolar canal. In general, higher measurement values were obtained for men when compared to women (p<0.05).

CONCLUSION

CBCT assessment of the third molar region provided useful information regarding impacted mandibular third molar surgery operations.

Cross-Sectional Imaging of Third Molar-Related Abnormalities

Third molars may be associated with a wide range of pathologic conditions, including mechanical, inflammatory, infectious, cystic, neoplastic, and iatrogenic. Diagnosis of third molar-related conditions can be challenging for radiologists who lack experience in dental imaging. Appropriate imaging evaluation can help practicing radiologists arrive at correct diagnoses, thus improving patient care. This review discusses the imaging findings of various conditions related to third molars, highlighting relevant anatomy and cross-sectional imaging techniques. In addition, key imaging findings of complications of third molar extraction are presented.

Principles of Exodontia

Exodontia services comprise the largest portion of clinical practice for most oral and maxillofacial surgeons in the United States. This article is an overview of the principles of exodontia including the physics principles underlying the appropriate use of dental elevators and forceps. Failure to understand the instrumentation and the physics principles being used can cause prolonged operative time, iatrogenic injury to the patient, and unnecessary fatigue and/or injury to the provider. Advances in materials, technology, and innovative design have produced interesting new instruments for exodontia. New instruments including periotomes, piezosurgery, physics forceps, and vertical extraction systems are introduced and reviewed.

An investigation into dose optimisation for imaging root canal anatomy using cone beam CT

OBJECTIVES

To identify a dose as low as diagnostically acceptable and a threshold level of image quality for cone beam CT (CBCT) imaging root canals, using maxillary first molar (M1M) second mesiobuccal (MB2) canals of varying complexity for two CBCT scanners.

METHODS

Dose-area product (DAP) and contrast-to-noise ratio (CNR) were measured for two scanners at a range of exposure parameters. Subjective-image-quality assessment at the same exposures was performed for three M1Ms of varying MB2 complexity, positioned in an anthropomorphic phantom. Nine raters (three endodontists, three dental radiologists and three junior staff) assessed canal visibility, using a 5-point confidence scale rating.

RESULTS

Identification of simple-moderate MB2 canal complexity was achieved at a range of protocols, with DAP values of ≥209.3 and ≥203.2 mGy cm² and CNRs of 3 and 7.6 for Promax^®3D and Accuitomo-F170^® respectively. For complex canal anatomy, target subjective image quality was not achieved, even at the highest DAP values for both scanners. Junior staff classified significantly more images as undiagnostic compared with senior staff (p = 0.043).

CONCLUSIONS

In this first study to address optimisation of CBCT imaging of root canal anatomy, a similar threshold dose for both scanners was identified for M1Ms with simple-moderate MB2 canal complexity. Increasing dose to enhance visualisation of more complex canal anatomy was ineffective. Selection of standard protocols (while avoiding lower kV/mA protocols) instead of high-resolution scans was a practical means of reducing patient dose. CNR is not a transferable measure of image quality.

Bucco alveolar bone thickness of mandibular impacted third molars with different inclinations: a CBCT study

PURPOSE

To compare the buccal alveolar bone thickness of mesioangulated mandibular impacted third molars (MITM) with buccal versus lingual inclination using cone-beam computed tomography (CBCT).

METHODS

This retrospective cross-sectional study evaluated 69 individuals (39 women and 30 men) who presented a total of 101 mesioangulated MITM according to the Winter classification and in B position according to the Pell and Gregory classification. The average age was 22.99 ± 3.94 years. The superior, medial and inferior alveolar thickness regarding buccal (n = 44) or lingual (n = 57) mandibular third molar inclination were measured. T test or Mann-Whitney U test and finally, a multiple linear regression were applied (p < 0.05).

RESULTS

The buccal alveolar bone thickness of mesioangulated mandibular impacted third molars was significantly greater in the group with lingual inclination compared to the group with buccal inclination, in the superior region (6.21 ± 3.27 vs. 4.85 ± 3.06; p = 0.036). The lingual inclination significantly influenced the buccal alveolar bone thickness in the middle region (p = 0.011).

CONCLUSIONS

The mesioangulated MITM in B position with lingual inclination have a greater thickness of the superior and medial buccal alveolar bone than the MITM with buccal inclination. These results should be considered during MITM diagnosis and surgical planning.

CBCT does not reduce neurosensory disturbances after third molar removal compared to panoramic radiography: a systematic review and meta-analysis

OBJECTIVES

The current dentistry scenario is showing an increase in the availability of cone-beam computed tomography (CBCT) in dental offices. Oral surgeons are using three-dimensional information as an additional tool to assess preoperative data for lower third molar (LTM) removal in moderate and high-risk cases of inferior alveolar nerve (IAN) injury diagnosed through the panoramic radiography (PR). The aim of this study is to identify whether CBCT examination reduces neurosensoric disturbances (ND) following the removal of the LTM when compared to PR.

MATERIALS AND METHODS

PubMed, Embase, Web of Science, Science Direct, and Scopus electronic databases were searched for studies published up to February 2019. The gray literature was also searched including papers that eventually met the eligibility criteria. Meta-analysis was performed using the comprehensive meta-analysis software, p < 0.05 considered significant.

RESULTS

Among the search, 6 studies met all eligibility criteria. There was no statistically significant difference between the two groups (PR and CBCT) in all six studies regarding reducing ND (95%. Confidence interval, 0,788-1734; heterogeneity: Q = 10,361; I² = 22.788%).

CONCLUSIONS

CBCT was not superior to PR in avoiding ND. However, further studies are necessary with standardized parameters for a better comparability between variables in the studies.

CLINICAL RELEVANCE

To better understand the CBCT clinical applicability in LTM removal to avoid unnecessary extra radiation when compared to PR to the patient and to improve patient's prognosis.

Can Cone-beam Computed Tomography Change Endodontists' Level of Confidence in Diagnosis and Treatment Planning? A Before and After Study

INTRODUCTION

This study evaluated the influence of cone-beam computed tomography (CBCT) on endodondists' level of confidence in their diagnosis of endodontic cases and their treatment plans.

METHODS

Twenty clinical cases with periapical radiographs and small-volume CBCT scans were classified according to the American Association of Endodontists guidelines. Information was provided on patient clinical history, and both extraoral and intraoral examinations were simulated. Fifteen endodontists filled out 2 questionnaires. In the first (Q1), the clinical description and a periapical radiograph were presented, followed by the questions. Thirty days later, they answered a second questionnaire (Q2) containing the same clinical description and CBCT. Their confidence in diagnosis and treatment planning was analyzed before and after receiving the tomographic images. Responses were recorded on a 5-point Likert scale, and the Wilcoxon test was used to investigate before and after levels of confidence in diagnosis and treatment planning.

RESULTS

The CBCT images influenced confidence in diagnosis and treatment planning of endodontic cases classified as complex (Wilcoxon test; P ≤ .05). There was a substantial change in the treatment planned in both moderate and complex cases after CBCT. Case complexity did not affect the participants' decision to request complementary information through CBCT.

CONCLUSIONS

In complex cases, CBCT increased endodontists' confidence to diagnose and plan treatment, when compared with periapical radiographs. Endodontists tended to recommend intervention when periapical images were supplemented with CBCT. CBCT proved to be an imaging method that influences endodontists' preoperative evaluation and treatment choice.

Risk factors for external root resorption of maxillary second molars due to impacted third molars as evaluated using cone beam computed tomography

The purpose of this retrospective study was to evaluate risk factors for external root resorption (ERR) on maxillary second molars (MxM2) in association with impacted third molars (MxM3) using cone beam computed tomography (CBCT) scans. The angles between the axes of MxM2/MxM3 (inclination) were measured. Further, ERR on MxM2 was classified as absent, slight, moderate, or severe. Contact location between MxM3 and MxM2, the size of the dental follicle, type of impaction, root formation, and patient demographic characteristics were also assessed. Half of the 84 MxM2 showed ERR (slight 36.9%, moderate 6.0%, severe 7.1%). Patient age was a significant factor for the presence of ERR (P = 0.03). The inclination was also a relevant factor, with transverse MxM3 exhibiting the highest risk of ERR (P = 0.02). The cervical third (28.6%) showed a significantly lower risk percentage of ERR compared to the apical (73.7%) and middle thirds (60.6%) of the root (P = 0.004). Based on these findings, clinicians assessing the need for surgical removal should be able to selectively identify impacted MxM3 at risk of causing ERR on MxM2 early on, especially when the MxM3 is located in close contact with the apical and middle thirds of the MxM2 roots and has a transverse inclination.

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.

Cone Beam Computed Tomography in Oral and Maxillofacial Surgery: An Evidence-Based Review

Cone Beam Computed Tomography (CBCT) is a valuable imaging technique in oral and maxillofacial surgery (OMS) that can help direct a surgeon’s approach to a variety of conditions. A 3-dimensional analysis of head and neck anatomy allows practitioners to plan appropriately, operate with confidence, and assess results post-operatively. CBCT imaging has clear indications and limitations. CBCT offers the clinician 3-dimensional and multi-planar views for a more accurate diagnosis and treatment without the financial burden and radiation exposure of conventional computed tomography (CT) scans. Furthermore, CBCT overcomes certain limitations of 2-dimensional imaging, such as distortion, magnification, and superimposition. However, CBCT lacks the detailed depiction of soft tissue conditions for evaluation of pathologic conditions, head and neck infections, and temporomandibular joint (TMJ) disc evaluation. This review evaluates the evidence-based research supporting the application of CBCT in the various fields of oral and maxillofacial surgery, including dentoalveolar surgery, dental implants, TMJ, orthognathic surgery, trauma, and pathology, and will assess the value of CBCT in pre-operative assessment, surgical planning, and post-operative analysis when applicable. Additionally, the significant limitations of CBCT and potential areas for future research will be discussed.

Cone beam CT imaging of the mandibular third molar: a position paper prepared by the European Academy of DentoMaxilloFacial Radiology (EADMFR)

OBJECTIVES

Lack of evidence on the use of CBCT for management of mandibular third molars in Radiation Protection guideline no. 172 of the European Commission made the European Academy of DentoMaxilloFacial Radiology (EADMFR) decide to update the recommendations of the guideline.

METHODS AND MATERIALS

A literature search was performed addressing the following questions: (1) does CBCT change the treatment of the patient?; (2) does CBCT reduce the number of post-operative sensory disturbances of the inferior alveolar nerve?; and (3) can CBCT predict the risk for a post-operative sensory disturbance of the inferior alveolar nerve?

RESULTS: 

Since the European Commission published the guideline in 2012 several high-evidence studies on the use of CBCT before removal of mandibular third molars have been conducted including five randomized controlled clinical trials and one meta-analysis. Present literature allows to propose recommendations with highest level of evidence.

CONCLUSION

New and up-to-date evidence-based recommendations advocate that CBCT imaging of the mandibular third molar should not be applied as a routine method before removal of mandibular third molars and therefore, CBCT imaging should only be applied when the surgeon has a very specific clinical question in an individual patient case that cannot be answered by conventional (panoramic and/or intraoral) imaging.

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.

Performance of different imaging techniques in the diagnosis of head and neck cancer mandibular invasion: A systematic review and meta-analysis

BACKGROUND

To assess diagnostic efficacy of imaging techniques for mandibular invasion by head and neck cancer.

METHODS

Thirteen databases were searched. Study inclusion, data-extraction and quality assessment were performed independently. STATA 14.0 were mainly used for meta-analysis.

RESULTS

Forty-nine studies were included. For mandibular invasion (cortex and marrow), CBCT, SPECT, CT, MRI, orthopantomography, PET-CT and bone-scintigraphy showed pooled sensitivities of 90%, 97%, 73%, 88%, 75%, 90%, 92%, specificities of 85%, 69% 91%, 90%, 83%, 89%, 79%, AUC of 0.9461, 0.9434, 0.8995, 0.9296, 0.8761, 0.9290, 0.9207, respectively. The combined SROC curves indicated CBCT and SPECT were superior to other techniques. For mandibular medullary invasion (marrow), CT and MRI showed pooled sensitivities of 85% and 93%, specificities of 86% and 84%.

CONCLUSIONS

CBCT was top-priority choice for bone invasion diagnosis. SPECT was recommended for exclusion, CT and MRI were suitable for conformation. Further investigations are needed for mandibular medullary involvement.

Assessment of impacted and partially impacted lower third molars with panoramic radiography compared to MRI-a proof of principle study

OBJECTIVES

Third molars often require surgical removal. Since three-dimensional radiological assessment is often indicated in difficult cases to avoid surgical complications, the radiation burden has to be considered. Here, MRI may offer a dose-free alternative to conventional X-ray techniques. The aim of this retrospective analysis was to evaluate the assessment quality of MRI compared to panoramic radiography in impacted and partially impacted lower third molars.

METHODS

Panoramic radiographs and MRI scans of 28 Caucasian patients were assessed twice by four investigators. Wisdom teeth were classified according to Juodzbalys and Daugela 2013.

RESULTS

When radiological lower third molar assessments with panoramic radiography and MRI were compared, staging concurred in 73% in the first round of assessments and 77% in the second.

CONCLUSIONS

The presented study demonstrates that MRI not only provides much the same information that panoramic radiography usually does, but also has the advantages of a dose-free three-dimensional view. This may facilitate and shorten third molar surgery. Image interpretation, however, can differ depending on training and experience.

Prediction of detectability of the mandibular canal by quantitative image quality evaluation using cone beam CT

OBJECTIVES

To compare the results of a new quantitative image quality evaluation method that requires no observers with the results of receiver operating characteristic (ROC) analysis in detecting the mandibular canal (MC) in cone beam CT (CBCT) images.

METHODS

A Teflon (polytetrafluoroethylene) plate phantom with holes of different depths was scanned with two CBCT systems. One CBCT system was equipped with an image intensifier (Experiment 1), and the other was equipped with a flat panel detector (Experiment 2). Holes that were above the threshold gray value (ΔG), calculated using just-noticeable difference (JND), were extracted. The number of extracted holes was used as the index of the image quality, and was compared with the Az values calculated by ROC analysis to detect the MC.

RESULTS

The number of extracted holes reflected the influence of different scanning conditions, and showed a strong correlation with the Az values calculated by ROC analysis. Indices of the number of extracted holes corresponding to high Az values for detecting the MC were obtained in both experiments.

CONCLUSIONS

Our image quality evaluation method applying JND to images of a standardized phantom is a quantitative method that could be useful for evaluating the detectability of the MC in CBCT images.

Clinical guidelines for dental cone-beam computed tomography

Dental cone-beam computed tomography (CBCT) received regulatory approval in Japan in 2000 and has been widely used since being approved for coverage by the National Health Insurance system in 2012. This imaging technique allows dental practitioners to observe and diagnose lesions in the dental hard tissue in three dimensions (3D). When performing routine radiography, the examination must be justified, and optimal protection should be provided according to the ALARA (as low as reasonably achievable) principles laid down by the International Commission on Radiological Protection. Dental CBCT should be performed in such a way that the radiation exposure is minimized and the benefits to the patient are maximized. There is a growing demand for widespread access to cutting-edge health care through Japan's universal health insurance system. However, at the same time, people want our limited human, material, and financial resources to be used efficiently while providing safe health care at the least possible cost to society. Japan's aging population is expected to reach a peak in 2025, when most of the baby boomer generation will be aged 75 years or older. Comprehensive health care networks are needed to overcome these challenges. Against this background, we hope that this text will contribute to the nation's oral health by encouraging efficient use of dental CBCT.