Accuracy of the measurements from multiplanar and sagittal reconstructions of CBCT

Accuracy of conventional versus cone-beam CT-synthesised lateral cephalograms for cephalometric analysis: A systematic review

OBJECTIVE

To assess the accuracy of cone-beam computed tomography (CBCT)-synthesised lateral cephalograms (CSLCs) compared with conventional lateral cephalograms for cephalometric analysis in human participants and skull models.

METHODS

The authors performed a search of PubMed, Scopus, Google Scholar and Embase databases on 4 October 2021. Included studies met the following criteria: published in English; compared conventional lateral cephalograms and CSLCs; assessed hard- and soft-tissue landmarks; and were performed on human or skull models. Data extraction from eligible studies was performed by two independent reviewers. The quality of evidence was assessed using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist tool - diagnostic accuracy studies.

RESULTS

A total of 20 eligible articles were included in this systematic review. Of these 20 studies, 17 presented with a low risk of bias, while three were found to have a moderate risk of bias. Hard- and soft-tissue analyses were evaluated for each imaging modality. The findings reveal that CSLCs are accurate and comparable to conventional lateral cephalograms for cephalometric analysis and demonstrate good inter-observer reliability. Four studies reported a higher accuracy with CSLCs.

CONCLUSION

Overall, the diagnostic accuracy and reproducibility of CSLCs were comparable to conventional lateral cephalograms in cephalometric analysis. It is justified that patients who have an existing CBCT scan do not need an additional lateral cephalogram, minimising unnecessary radiation exposure, expenses and time for the patient. Larger voxel sizes and low-dose CBCT protocols can be considered to minimise radiation exposure.

REGISTRATION

This study was registered with PROSPERO (CRD42021282019).

Impact of different cephalometric skeletal configurations on anatomic midface parameters in adults

OBJECTIVES

Skull morphology and growth patterns are essential for orthodontic treatment, impacting clinical decision making. We aimed to determine the association of different cephalometric skeletal configurations on midface parameters as measured in 3D CT datasets.

MATERIALS AND METHODS

After sample size calculation, a total of 240 fully dentulous patients between 20 and 79 years of age (mean age: 42 ± 15), who had received a CT of the skull within the scope of trauma diagnosis or intracranial bleeding, were retrospectively selected. On the basis of cephalometric analysis, using MPR reconstructions, patients were subdivided into three different vertical skull configurations (brachyfacial, mesofacial, dolichofacial) and the respective skeletal Class I, II, and III relationships. Anatomic parameters were measured using a three-dimensional post-processing console: the thickness of the maxillary and palatine bones as well as the alveolar crest, maxillary body and sutural length, width and height of the hard palate, maxillary facial wall thickness, and masseter muscle thickness and length.

RESULTS

Individuals with brachyfacial configurations had a significantly increased palatal and alveolar ridge thicknesses compared to those with dolichofacial- or mesofacial configurations. Brachyfacial configurations presented a significantly increased length and thickness of the masseter muscle (4.599 cm; 1.526 cm) than mesofacial (4.431 cm; 1.466 cm) and dolichofacial configurations (4.405 cm; 1.397 cm) (p < 0.001). Individuals with a skeletal Class III had a significantly shorter palatal length (5.313 cm) than those with Class I (5.406 cm) and Class II (5.404 cm) (p < 0.01). Sutural length was also significantly shorter in Class III (p < 0.05).

CONCLUSIONS

Skeletal configurations have an impact on parameters of the bony skull. Also, measurable adaptations of the muscular phenotype could result.

CLINICAL RELEVANCE

The association between viscerocranial morphology and midface anatomy might be beneficial for tailoring orthodontic appliances to individual anatomy and planning cortically anchored orthodontic appliances.

Individual "alveolar phenotype" limits dimensions of lateral bone augmentation

AIM

Alveolar ridge resorption following tooth extraction often renders a lateral bone augmentation inevitable. Some patients, however, suffer from severe early (during graft healing, E_res ) and/or late (during follow-up, L_res ) graft resorption. We explored the hypothesis that the "individual phenotypic dimensions" may partially explain the degree of such resorptions.

MATERIALS AND METHODS

Patients who underwent a guided bone regeneration (GBR) procedure were screened for inclusion according to the following criteria: (1) a relatively symmetrical maxillary arch; (2) an intact contra-lateral alveolar bone dimension; (3) the availability of a pre-operative cone-beam CT (CBCT); (4) a CBCT taken immediately after GBR, and (5) at least one CBCT scan ≥6 months after surgery. CBCT scans from different timepoints were registered and imported into the Mimics software (Materialise, Leuven, Belgium). Bone dimensions of the contra-lateral site of the augmentation, representing the "individual phenotypical dimension (IPD) of the alveolar crest", were superimposed on the augmented site and registered accordingly. As such, E_res and L_res could be measured over time, in relation to the IPD (in two dimensions; per millimetre apically from the alveolar crest, in the centre of the GBR), as well as in three dimensions (the entire GBR, 2 mm away from the mesial, distal, and apical border for standardization).

RESULTS

A total of 17 patients (23 augmented sites) were included. After E_res , the outline of the augmentation was in general located ±1 mm outside the IPD, but ≥1.5 years after GBR, it further moved towards the IPD (85% within 0.5 mm distance).

CONCLUSIONS

Within the limitations of this study, the results indicate that the dimensions of a lateral bone augmentation are defined by the "individual phenotypic bone boundaries" of the patient.

Application of a Cone-Beam Computed Tomography-Based Index for Evaluating Surgical Sites Prior to Sinus Lift Procedures-A Pilot Study

OBJECTIVES

Radiography-based indices can help surgeons perform detailed examinations of the surgical site and predict the surgical difficulty of cases. We aimed to develop and validate a novel CBCT-based index that can predict the surgical difficulty of sinus-augmentation procedures.

MATERIALS AND METHODS

In the first stage, five experienced dental specialists performed a review of the literature and closed group discussions and designed the novel index. In the next stage, the index was validated. CBCT scans of 30 patients scheduled for sinus-augmentation procedures were evaluated and assigned presurgical CBCT evaluation scores (PSCESs) by five examiners. Subsequently, one oral surgeon performed sinus augmentation using the lateral antrostomy technique and assigned surgical difficulty scores (SDSs) to each of the 30 cases along with 2 observers. The PSCESs and SDSs were statistically analysed to determine the interrater reliability and validity of the index.

RESULTS

The interrater agreement of the PSCES among the five presurgical evaluators was 0.85. The PSCES of the five evaluators had highly significant correlation (P < 0.001, r = 0.68 to 0.76) with the SDS. Regression analysis revealed that for every unit increase in the PSCES, there is 0.46 to 0.57 increase in the SDS value.

CONCLUSION

The results of this pilot study revealed that a novel CBCT-based index can be used as a reliable tool for predicting the surgical difficulty of sinus-augmentation procedures. However, the novel index needs to be tested on a larger sample of patients and evaluators for a more concrete validity and reliability.

Orthodontic incisor decompensation in orthognathic therapy-success and efficiency in three dimensions

Objectives

Sufficient dental decompensation is crucial for treatment success in combined orthodontic-surgical treatment. The study’s objective was to determine the treatment success and efficiency in sagittal, vertical, and transversal decompensation.

Methods

This longitudinal, observational study enrolled 52 adult patients, who underwent orthodontic-surgical treatment. Incisor inclinations and positions as well as skeletal changes were assessed pre-treatment (T1), pre-surgical (T2), and post-surgical (T3) by lateral cephalograms and CBCT scans.

Results

Incisor decompensation was insufficient in all three dimensions. Sagittal: treatment efficiency did not differ between class II and III patients. Vertical: patients with open bite demonstrated pre-surgical bite deepening and insufficient surgical reduction of the maxillomandibular plane angle. Transversal: Dental midline deviations were not adapted to the skeletal asymmetry so that menton deviations were not properly corrected.

Conclusions

Incisor decompensation was not as successful as requested in all three dimensions and the treatment ideal was seldom achieved.

Clinical relevance

To improve the skeletal outcome, the orthodontist has to treat the patient with the desired surgical movements in mind and should critically evaluate the pre-surgical incisor decompensation before referral to the surgical team.

Linear measurement accuracy of CBCT panoramic reconstructions: experimental study with dry human mandibles

INTRODUCTION

Studies on software accuracy of reformatted panoramic computed tomography (CT) images are scarce.

OBJECTIVES

The aim of this study was to evaluate the software accuracy of reformatted panoramic views from cone-beam computed tomography (CBCT).

METHODS

Ten dry mandibles were scanned using CBCT with different voxel sizes. Following the reconstruction of panoramic views with three different software, horizontal and vertical linear measurements were performed using the electronic rules of each software. Measurements of the corresponding dry mandibles were taken with a digital caliper and defined as the gold standard.

RESULTS

There were no statistically significant differences in linear distances among the dry mandibles and reformatted panoramic CT views. The relative error ranged from 1.3 to 8.0%, depending on the software and voxel size.

CONCLUSIONS

The linear measurements on reformatted panoramic views are reliable.