An optimized imaging protocol for orofacial cleft patients

Optimization of orofacial cleft imaging protocols using device-specific low-dose cone-beam computed tomography

OBJECTIVE

The aim of this study was to present optimized device-specific low-dose cone-beam computed tomography (CBCT) protocols with sufficient image quality for pre-surgical diagnostics and three-dimensional (3D) modelling of cleft defects.

METHODS

Six paediatric skulls were acquired, and an artificial bony cleft was created. A high-resolution CBCT scan acted as a reference standard (Accuitomo 170, Morita, Kyoto, Japan) for comparing eight low-dose protocols of Newtom VGi-evo (QR Verona, Cefla, Verona, Italy), which included Eco and Regular protocols with different field of views (FOVs). Delineation of lamina dura, cementoenamel junction (CEJ), trabecular bone and bony bridge were assessed. A 3D model of the defect was also evaluated.

RESULT

The dose area product of low-dose protocols ranged from 31 to 254 mGy*cm2. Despite the dose difference of up to eight times between applied protocols, trabecular bone and CEJ exhibited appropriate image quality in all scans. However, Regular small FOV protocols (5 × 5 and 8 × 5 cm2), for both lamina dura and bony bridge, demonstrated a significant improvement in image quality compared to Eco FOV counterparts. Based on 3D defect analysis, no significant difference existed between low-dose protocols and the reference standard.

CONCLUSION

The findings highlight the possibility of achieving a considerable reduction (up to eight times) in the radiation dose using low-dose CBCT protocols while maintaining sufficient image quality for assessing anatomical structures and 3D modelling in cleft cases.

Three-dimensional evaluation of secondary alveolar bone grafting in patients with unilateral cleft lip and palate: A 2-3 year post-operative follow-up

OBJECTIVES

The present study aims to quantitatively assess secondary alveolar bone graft (SABG) resorption in unilateral cleft lip, alveolus and palate (UCLAP) patients in a 2-3 year longitudinal follow-up setting by using a validated 3D protocol. Furthermore, the potential relation of SABG resorption with maxillary canine position and a number of patient-related factors was investigated.

METHODS

UCLAP patients who underwent SABG and had good quality CBCT images at the following timepoints were included in the study: pre-operative (T0), immediate (T1), 6 months (T2) and either 1-2 years (T3) or 2-3 years (T4) post-operative. The final bone grafted region was defined on the T1 scans and refined in the registered T0 scans. The bone graft after resorption was determined by applying threshold-based segmentation on the registered T2, T3 or T4 scans within the segmented bone graft volume. The position of the canines was determined at every timepoint at the cleft and non-cleft side.

RESULTS

Forty-five UCLAP patients (mean age 9.0 ± 1.3 years) were included. In the first 6 months after SABG, 43.6% bone resorption was recorded. 2-3 years post-operative, 56% bone resorption was found if the maxillary canine was not yet erupted and 42.7% if it erupted through the graft. The vertical position of the canines was significantly higher on the cleft side at T3.

CONCLUSIONS

The present study reports significant SABG resorption over time. However, no correlation was found between SABG resorption and canine position, nor between other patient-related factors.

Repeat Buccal Flaps Successfully Reduce Hypernasality in a Patient with Cleft Palate

Surgical intervention can contribute to the development of velopharyngeal insufficiency (VPI) leading to hypernasality and regurgitation. In this case, a patient with a history of bilateral buccal flaps used for her primary CP repair presented to clinic with hypernasality and VPI as assessed by speech exam and imaging. She underwent repeat bilateral buccal flap palatal lengthening with division of the pedicles 3 months later. Three months after her division, her hypernasality score improved from moderate to mild and her posterior gap decreased. This study concluded buccal flaps can be used a second time for patients needing palatal revisions for VPI.

Validation and comparison of 2D grading scales and 3D volumetric measurements for outcome assessment of bone-grafted alveolar clefts in children

BACKGROUND

Several methods have been proposed to assess outcome of bone-grafted alveolar clefts on cone beam computed tomography (CBCT), but so far these methods have not been compared and clinically validated.

OBJECTIVES

To validate and compare methods for outcome assessment of bone-grafted clefts with CBCT and provide recommendations for follow-up.

METHODS

In this observational follow-up study, two grading scales (Suomalainen; Liu) and the volumetric bone fill (BF) were used to assess the outcome of 23 autogenous bone-grafted unilateral alveolar clefts. The mean age at bone grafting was 9 years. The volumetric BF was assessed in five vertical sections. The bone-grafted cleft outcome was based on a binary coding (success or regraft) on a clinical multidisciplinary expert consensus meeting. Grading scales and volumetric assessment were compared in relation to the bone-grafted cleft outcome (success or regraft). Reliability for the different outcome variables was analyzed with intra-class correlation and by calculating kappa values.

LIMITATIONS

The study had a limited sample size. Clinical CBCT acquisitions had a varying tube current and exposure time.

RESULTS

Volumetric 3D measurements allowed for outcome assessment of bone-grafted alveolar clefts with high reliability and validity. The two grading scales showed highly reliable outcomes, yet the validity was high for the Suomalainen grading scale but low for the Liu grading scale.

CONCLUSIONS

Volumetric 3D measurement as well as the Suomalainen grading can be recommended for outcome assessment of the bone-grafted cleft. Yet, one must always make a patient-specific assessment if there is a need to regraft.

Do Buccal Flaps Improve Velopharyngeal Insufficiency in Conversion Furlow Palatoplasty for Patients with Cleft Palate?

SUMMARY

Velopharyngeal insufficiency (VPI) is a complication following primary palatoplasty that can lead to hypernasality of the voice and other speech problems. The conversion Furlow palatoplasty for VPI can be performed with the addition of buccal flaps to provide additional tissue for palatal repair. In this study, the authors aimed to determine the effectiveness of buccal flaps with conversion Furlow palatoplasty in secondary management of VPI. A retrospective review of patients undergoing surgical repair of VPI between 2016 and 2020 was performed. Patients underwent either conversion Furlow palatoplasty alone (FA) or conversion Furlow palatoplasty with buccal flaps (FB) for VPI after primary straight-line repair of the palate. The authors reviewed medical records to collect demographics, operative information, and preoperative and postoperative speech scores. Of the 77 patients in the study, 16 (21%) had a revision that incorporated buccal flaps. The median age at cleft palate revision surgery was 8.97 years in the FA group and 7.96 years in the FB group ( P = 0.337). In the FA group, four patients (7%) developed a postoperative fistula, compared with zero patients in the FB group. The average time to follow-up after revision surgery was 3.4 years (range, 7 months to 5.9 years). Both cohorts demonstrated a decrease in hypernasality and total parameter scores postoperatively. The use of buccal flaps in revision Furlow palatoplasty could decrease the risk for postoperative complications. The use of data from a larger patient population from multiple institutions is warranted to determine true significance.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Radiographic Assessment of Cleft Alveolar Bone Defects: A Preliminary Comparison of Periapical and Cone Beam Computed Tomography Images

BACKGROUND & PURPOSE

Accurate radiographic assessment of secondary alveolar bone grafting (SABG) is critical in evaluating SABG outcomes in patients with cleft lip and palate. This study compared Periapical (PA) and Cone beam computed tomography (CBCT) grading of SABG outcomes and conducted an analysis of agreement rate between the two imaging modalities.

METHODS

A retrospective chart review was performed of patients who underwent secondary alveolar bone grafting at a single institution. Bone quality of the alveolar cleft site was assessed at three root levels of the adjacent teeth on PA and CBCT images.

RESULTS

48 patients had pre- or post-operative images with both CBCT and PA that were appropriate for comparison. A total of 174 alveolar bone sections (three root levels of adjacent teeth in 58 pairs) were graded on CBCT and PA images. Agreement of CBCT grading with PA grading was 41.3% (72/174) overall. CBCT assessments rated bone quality lower than PA grading in 51.2% (89/174) of sections. CBCT had higher grading than PA image grading in 7.5% (13/174) of sections. The weighted Cohen Kappa value for comparison of CBCT and PA readings was 0.17, indicating a low rate of agreement. Wilcoxon signed rank test demonstrated that the difference between grading on CBCT and PA assessments was statistically significant (P < .001).

CONCLUSIONS

CBCT and PA readings demonstrated an overall low rate of agreement in the assessment of cleft alveolar bone. This investigation suggests that PA radiographs have lower sensitivity in detecting poor bone grafting outcomes.

Cumulative exposure and lifetime cancer risk from diagnostic radiation in patients undergoing orthognathic surgery: a cross-sectional analysis

Radiation doses in dentomaxillofacial imaging are typically very low. However, diagnostic and follow-up protocols in orthognathic surgery result in a patient-specific risk in effective dose. Estimating the cancer risks from these exposures remains abstract for many maxillofacial surgeons. In this study, 40 orthognathic patients were randomly sampled and their cumulative effective dose (ED) calculated. The lifetime attributable risk of cancer (LAR) was calculated based on the standard radiological protocol for orthognathic surgery follow-up using methods described in the BEIR VII report and RadRAT. The mean cumulative ED of the 40 sampled patients at the end of their 2-year follow-up period was 1.91 ± 0.58 mSv. The LAR at the end of follow-up was 17.65 (90% confidence interval 6.46-32.90) per 100,000 person-years for male orthognathic patients and 13.93 (90% confidence interval 6.27-25.24) per 100,000 person-years for female orthognathic patients. This represents 0.70% and 0.68%, respectively, of the baseline cancer risk for oral, thyroid, and brain cancer combined. Although theoretical, these results provide a framework for interpreting radiation doses and cancer risks in patients undergoing orthognathic surgery. Considering the increased radiation sensitivity in children and adolescents, indication-oriented and patient-specific imaging protocols should be advised.

Moving toward patient specificity for devising cone-beam computed tomography field-of-views: A normative maxillary skeletal dimensional analysis

BACKGROUND

A lack of evidence exists comprehensively assessing skeletal dimensions in a Caucasian population group at different ages.

AIM

To provide age- and gender-specific normative skeletal dimensional measurements of the maxillary region using cone-beam computed tomography (CBCT) imaging.

DESIGN

Cone-beam computed tomography images of Caucasian patients were acquired and divided into different age groups ranging from 8 to 20 years. Linear measurements were taken to evaluate seven distance-based variables, which included anterior nasal spine-posterior nasal spine (ANS-PNS) distance, bilateral maxillary first molar's central fossae (CF) distance, palatal vault depth (PVD), bilateral palatal cementoenamel junction (PCEJ) distance, bilateral vestibular CEJ (VCEJ) distance, bilateral jugulare distance (Jug) and arch length (AL).

RESULTS

A total of 529 patients (243 male, 286 female) were selected. ANS-PNS and PVD showed the highest change in dimensions from 8 to 20 years of age. On the contrary, AL had the least variability in all age groups. Male patients had larger dimensions and showed a significant change in all dimensional measurements (p < .001) than female patients.

CONCLUSION

The maxillary linear dimensions varied across different age groups. The presented maxillary normative data could serve as a reference guide for devising patient-specific CBCT field of views.

Validation of a novel method for canine eruption assessment in unilateral cleft lip and palate patients

Objective

The aim of this study was to propose and validate a three‐dimensional (3D) methodology for the assessment of canine eruption in patients born with unilateral cleft lip and palate (UCLP) following secondary alveolar bone graft (SABG).

Methods and Materials

A total of 10 patients (four females, six males; mean age: 8.8 years) with UCLP who underwent SABG were recruited. Pre‐ and 6‐month post‐operative cone‐beam computed tomography (CBCT) was acquired for all patients. Post‐operative data was registered onto pre‐operative data utilizing voxel‐based registration. Following superimposition, a segmentation process was applied to segment maxillary canine on both cleft and non‐cleft side. Thereafter, translational and rotational changes in canine position were assessed for both cleft and non‐cleft side by two observers.

Results

The intra‐class correlation coefficient (ICC) indicated excellent reliability (≥0.90) with inter and intra‐observer error of less than 0.05 mm. The overall ICC was found to be high for assessing both translational and rotational changes. The mean absolute inter‐ and intra‐observer difference for translational and rotational changes was found to be less than 1 mm and 3°.

Conclusion

The present method was found to be reliable proving to be clinically applicable for assessing maxillary canine eruption changes in both cleft and non‐cleft bone.

Dental development in patients with and without unilateral cleft lip and palate (UCLP): a case control study

OBJECTIVE

To evaluate if the presence of unilateral cleft lip and palate (UCLP) causes delay in dental age and tooth development.

MATERIALS AND METHODS

Panoramic radiographs of 189 non-syndromic UCLP patients, aged from 6 to 20 years, were collected. Two measures of tooth development were examined: dental maturity scale for the seven left mandibular teeth (dental age-DA) and the degree of each tooth development (developmental score-DS). All the teeth except third molars were staged according to the Demirjian's method. The data of the cleft group were compared with a control group matched for age and gender, based on the findings observed in other 189 panoramic radiographs.

RESULTS

At all ages, DA was lower in the UCLP group, but not always significantly; the highest difference was - 1.411 for females at 13 years old and - 0.776 for males at 12 years old. DS of all teeth was significantly lower in the UCLP group, at all ages under 17 in females, and at all ages under 18 in males. In UCLP group, tooth development was more delayed in the maxilla compared with the mandible. No evidence of a slower development at the cleft side compared with the non-cleft side was highlighted.

CONCLUSIONS

Significant lower dental development was observed in UCLP patients compared with control ones by using DS and DA indexes.

CLINICAL RELEVANCE

These findings can help the clinicians in establishing a proper orthodontic and surgical diagnosis and treatment planning in UCLP patients and for forensic age estimation's purposes.