Volumetric Analysis of Alveolar Bone Defect Using Three-Dimensional-Printed Models Versus Computer-Aided Engineering

Application of 3D Printing in Cleft Lip and Palate Repair

This manuscript reviews the transformative impact of 3-dimensional (3D) printing technologies in the treatment and management of cleft lip and palate (CLP), highlighting its application across presurgical planning, surgical training, implantable scaffolds, and postoperative care. By integrating patient-specific data through computer-aided design and manufacturing, 3D printing offers tailored solutions that improve surgical outcomes, reduce operation times, and enhance patient care. The review synthesizes current research findings, technical advancements, and clinical applications, illustrating the potential of 3D printing to revolutionize CLP treatment. Further, it discusses the future directions of combining 3D printing with other innovative technologies like artificial intelligence, 4D printing, and in situ bioprinting for more comprehensive care strategies. This paper underscores the necessity for multidisciplinary collaboration and further research to overcome existing challenges and fully utilize the capabilities of 3D printing in CLP repair.

Influence of osseous structure characteristics of unilateral alveolar cleft on outcomes of alveolar bone grafting: a retrospective study

BACKGROUND

To enhance the success rate of alveolar bone grafting, it is crucial to identify the factors that may influence the postoperative bone formation. This study aimed to investigate the impact of various osseous structure characteristics of alveolar clefts on the survival ratio of autogenous cancellous bone particle grafts.

METHODS

A retrospective study was conducted on 60 patients who underwent surgery performed by the same surgeon between 2016 and 2022. Two researchers measured and recorded the bone defect volume (DV), postoperative bone formation volume at 1 year, contact area between the graft and the bone surface within the cleft (S), cleft width (CW), osseous occlusion relationships, and presence of a cleft palate and initial bone bridge within the cleft for each patient. Pearson correlation analysis, Spearman's correlation analysis, and multiple linear regression analysis were performed.

RESULTS

The analysis results revealed statistical correlations between DV, CW, ratio of S to DV, cleft palate, initial bone bridge presence, and occlusion relationships with the survival rate. Multiple linear regression analysis showed that initial bone bridge and occlusion relationships affected the graft survival rate.

CONCLUSIONS

Based on the presence of initial bone bridges and occlusions, we can make a rough estimate of the postoperative bone formation outcome in patients. However, the underlying mechanisms by which these two factors influence the bone formation require further investigation. In addition, preoperative orthodontic treatment to improve occlusal relationships may improve the postoperative bone formation outcomes in alveolar bone grafting.

Comparison of Preoperative Measurement Methods of Alveolar Cleft Volume Using Cone Beam Computed Tomography between Computer Simulation and Water Displacement Methods

OBJECTIVE

To compare the use of a computer simulation by Mimics software and the water displacement method as means for measurement of alveolar cleft volume on cone beam computed tomography (CBCT) data.

DESIGN

Prospective study.

SETTLING

Institutional research.

PATIENTS

Patients with unilateral complete cleft lip and palate (UCCLP) who would undergo alveolar bone grafting.

INTERVENTIONS

CBCT images of twenty patients with UCCLP were included in the study. In the first method, the water displacement method was adopted to measure volume of plasticine filled in the alveolar cleft imprinted on 3D printed model of maxilla. In the second method a volumetric assessment function in Mimics software was adopted to measure volume of 3D virtual model of alveolar cleft constructed from CBCT images. A comparison on the alveolar cleft volumes derived from the two methods was assessed using the statistical paired t-test.

MAIN OUTCOME MEASURE

The paired-t test showed no statistically significant difference between alveolar cleft volumes measured by the two methods (P = 0.075).

RESULTS

Mean volume of the alveolar cleft measured by the water displacement method was 1.03 ± 0.31 ml whereas by the computer simulation using Mimics software the value was 1.00 ± 0.31 ml. The mean difference between the two methods was 0.03 ± 0.08 ml.

CONCLUSION

The computer simulation by Mimics software as a means for measurement of alveolar cleft volume on CBCT data is as accurate as the measurement by the water displacement method.

Increased rate of pseudarthrosis in the anterior intersegmental gap after mandibular reconstruction with fibula free flaps: a volumetric analysis

OBJECTIVES

Pseudarthrosis after mandibular reconstruction leads to chronic overload of the osteosynthesis and impedes dental rehabilitation. This study evaluates the impact of gap site on osseous union in mandible reconstruction using a new volumetric analysis method with repeated cone-beam computed tomography (CBCT).

METHODS

The degree of bone regeneration was evaluated in 16 patients after mandible reconstruction with a fibula free flap and patient-specific reconstruction plates. Percentual bone volume and width changes in intersegmental gaps were retrospectively analyzed using a baseline CBCT in comparison to a follow-up CBCT. Patients' characteristics, plate-related complications, and gap sites (anterior/posterior) were analyzed. Detailed assessments of both gap sites (buccal/lingual/superior/inferior) were additionally performed.

RESULTS

Intersegmental gap width (p = 0.002) and site (p < 0.001) significantly influence bone volume change over two consecutive CBCTs. An initial larger gap width resulted in a lower bone volume change. In addition, anterior gaps showed significantly less bone volume changes. Initial gap width was larger at posterior segmental gaps (2.97 vs 1.65 mm, p = 0.017).

CONCLUSIONS

A methodology framework has been developed that allows to quantify pseuarthrosis in reconstructed mandibles using CBCT imaging. The study identifies the anterior segmental gap as a further risk factor for pseudarthrosis in reconstructions with CAD/CAM reconstruction plates. Future research should evaluate whether this outcome is related to the biomechanics induced at this site.

A Novel and Practical Protocol for Three-Dimensional Assessment of Alveolar Cleft Grafting Procedures

OBJECTIVE

To evaluate the reproducibility and accuracy of a new, easy-to-use volumetric assessment of the alveolar cleft.

DESIGN

Twelve cone-beam computed tomography (CBCT) datasets of patients with a unilateral cleft lip, alveolus, and palate were evaluated by two investigators. Residual alveolar cleft calcified volume one year after surgery was analyzed by using standardized landmarks to determine the borders of the cleft defect and semi-automatically segment the alveolar cleft defect.

RESULTS

The Dice-coefficient between observers for the segmented preoperative alveolar cleft defect was 0.81. Average percentage of residual alveolar cleft calcified material was 66.7% one year postoperatively.

CONCLUSIONS

This study demonstrates a reliable and practical semi-automatic three-dimensional volumetric assessment method for unilateral clefts using CBCT.

Comparison of Two Methods for Presurgical Volumetric Evaluation of Alveolar Cleft Bone Defects Using Computer-Aided Engineering

ABSTRACT

Precise volumetric evaluation of the alveolar cleft facilitates accurate preparation of bone substitutes and reduces donor site morbidity. This study investigates 2 advanced presurgical volumetric assessment methods that use computer-aided engineering (CAE) software. Preoperative computed tomography (CT) scans from 20 unilateral alveolar cleft patients undergoing secondary alveolar bone grafting (SABG) were analyzed by CAE software. Cleft defect volumes were calculated using the mirror-reversed technique and the subtraction method. The mirror-reversed technique determines defect volume by reversing the noncleft side to the cleft side. The subtraction method determines defect volume by subtracting a mask of the preoperative cleft from a mask generated after simulated cleft filling. The mean defect volumes and calculation times of the mirror-reversed technique (1.27 ± 0.35 cm3; 11.80 ± 1.79 seconds) and the subtractive method (1.23 ± 0.32 cm3; 9.43 ± 1.35 seconds) did not differ significantly. In Bland-Altman analysis the 2 methods were equivalent for alveolar cleft defect assessment. Both methods exhibited acceptable interobserver reliability, high precision, clinical convenience, time efficiency, and high reproducibility, and can serve as valuable tools for the planning and execution of SABG. The subtraction method has broader potential applicability and can simulate intraoperative bone grafting more effectively.

Three-Dimensional Printing in Cleft Care: A Systematic Review

OBJECTIVE

To determine the current applications of 3-dimensional (3D) printing in the care of patients with cleft lip and palate. We also reviewed 3D printing limitations, financial analysis, and future implications.

DESIGN

Retrospective systematic review.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were used by 3 independent reviewers. Articles were identified from Cochrane library, Ovid Medline, and Embase. Search terms included 3D printing, 3 dimensional printing, additive manufacturing, rapid prototyping, cleft lip, and cleft palate. Exclusion criteria included articles not in English, animal studies, reviews without original data, oral presentations, abstracts, opinion pieces, and articles without relevance to 3D printing or cleft lip and palate.

MAIN OUTCOME MEASURES

Primary outcome measure was the purpose of 3D printing in the care of patients with cleft lip and palate. Secondary outcome measures were cost analysis and clinical outcomes.

RESULTS

Eight-four articles were identified, and 39 met inclusion/exclusion criteria. Eleven studies used 3D printing models for nasoalveolar molding. Patient-specific implants were developed via 3D printing in 6 articles. Surgical planning was conducted via 3D printing in 8 studies. Eight articles utilized 3D printing for anatomic models/educational purposes. 3-Dimensional printed models were used for surgical simulation/training in 6 articles. Bioprinting was utilized in 4 studies. Secondary outcome of cost was addressed in 8 articles.

CONCLUSION

3-Dimensional printing for the care of patients with cleft lip and palate has several applications. Potential advantages of utilizing this technology are demonstrated; however, literature is largely descriptive in nature with few clinical outcome measures. Future direction should be aimed at standardized reporting to include clinical outcomes, cost, material, printing method, and results.

Assessment of Bone Formation After Secondary Alveolar Bone Grafting With and Without Platelet-Rich Plasma Using Computer-Aided Engineering Techniques

The aim of this study was to analyze the newly formed bone volume (FV), 6 months after secondary alveoloplasty using iliac cancellous bone graft, with and without platelet-rich plasma (PRP). Forty patients with unilateral alveolar cleft were involved in this randomized, prospective, comparative study, with 20 patients each forming the control (group A) and PRP (group B) groups, respectively. The preoperative alveolar defect volume (DV) and the postoperative FV were automatically calculated by the computer-aided engineering software using the patients' pre and postsurgical computed tomography data. The volume of the actual bone graft (AV) was identical to the DV calculated before surgery. The bone formation ratio (BF%) was calculated as follows: BF% = (FV/AV) × 100%. The mean BF% was 42.54 ± 9.32% in group A and 46.97 ± 18.49% in group B. There was no statistically significant difference between the 2 groups for BF% (P > 0.05). The study presents a fast and accurate method for assessing the effect of PRP in alveolar grafting. However, the study found no conclusive evidence on the effect of PRP on bone growth.

An Accurate Volumetric Analysis Method for Evaluating Outcomes of Alveolar Cleft Reconstruction

An accurate volumetric analysis method for evaluating the outcomes of different types of alveolar cleft reconstruction is essential because it can help determine which graft material is more effective, confirm favorable times for alveolar bone grafting, and improve surgical techniques. This study aimed to introduce a novel method of precisely calculating the bone formation ratio using computer-aided engineering after surgery. A patient with a unilateral alveolar cleft who was treated with anterior iliac crest bone grafting was enrolled in this study. Helical computed tomography scans were performed preoperatively and 12 months postoperatively. The Digital Imaging and Communications in Medicine (DICOM) data were reconstructed as three-dimensional images and saved in the STL format by using Mimics software. STL data were processed by Geomagic Wrap 2017, using the Boolean operation, the newly formed bone of the alveolar was segmented by identifying the differences between the preoperative and the postoperative three-dimensional images. For this patient, the mean volume of the newly formed bone was 0.387 cm, the morphology was clear, the bone formation ratio was 41.4%, the mean time required for calculating the newly formed bone volume was 23 minutes, and the bone survival ratio was 38.7%. This method is a clinically practical, accurately measurement and time-saving method to evaluate the outcome of alveolar cleft reconstruction. Both the volumetric assessment and morphological analysis of the newly formed bone could be determined in a precise manner.

A novel accurate volumetric analysis protocol for evaluating secondary alveolar cleft reconstruction

An accurate volumetric analysis protocol for secondary alveolar cleft reconstruction is essential. It can help confirm favorable times for bone grafting, determine which graft material is more effective, and improve surgical techniques. This study aimed to introduce a novel protocol for precisely calculating the bone formation ratio (BF%) using computer-aided engineering. The helical computed tomography (CT) datasets of 14 patients who underwent alveolar cleft reconstruction was included in this study. CT scans performed preoperatively and 1 year postoperatively were evaluated by two investigators. Digital Imaging and Communications in Medicine (DICOM) data were reconstructed as three-dimensional (3D) images using Mimics software and processed by Geomagic Wrap (2017). Using the Boolean operation, the newly formed bone of the alveolar cleft was segmented by identifying the differences between pre- and postoperative 3D images. The volumetric assessment and morphological analysis of the newly formed bone could be determined in a precise manner, the mean BF% was 47.7% ± 16.4%, the mean time required for calculating was 23.57 ± 3.64 min. For the difference in the volume of newly formed bone between the two observers, the intraclass correlation coefficient (ICC) was 0.92, p < 0.001. This method is clinically practical and precise measurement, which has good reproducibility for evaluating outcome of different grafting materials for alveolar clefts.

Comparative Volume Analysis of Alveolar Defects by 3D Simulation

A precise volumetric assessment of maxillary alveolar defects in patients with cleft lip and palate can reduce donor site morbidity or allow accurate preparation of bone substitutes in future applications. However, there is a lack of agreement regarding the optimal volumetric technique to adopt. This study measured the alveolar bone defects by using two cone-beam computed tomography (CBCT)-based surgical simulation methods. Presurgical CBCT scans from 32 patients with unilateral or bilateral clefts undergoing alveolar bone graft surgery were analyzed. Two hands-on CBCT-based volumetric measurement methods were compared: the 3D real-scale printed model-based surgical method and the virtual surgical method. Different densities of CBCT were compared. Intra- and inter-examiner reliability was assessed. For patients with unilateral clefts, the average alveolar defect volumes were 1.09 ± 0.24 and 1.09 ± 0.25 mL (p > 0.05) for 3D printing- and virtual-based models, respectively; for patients with bilateral clefts, they were 2.05 ± 0.22 and 2.02 ± 0.27 mL (p > 0.05), respectively. Bland–Altman analysis revealed that the methods were equivalent for unilateral and bilateral alveolar cleft defect assessment. No significant differences or linear relationships were observed between adjacent different densities of CBCT for model production to obtain the measured volumes. Intra- and inter-examiner reliability was moderate to good (intraclass correlation coefficient (ICC) > 0.6) for all measurements. This study revealed that the volume of unilateral and bilateral alveolar cleft defects can be equally quantified by 3D-printed and virtual surgical simulation methods and provides alveolar defect-specific volumes which can serve as a reference for planning and execution of alveolar bone graft surgery.

Radiological Society of North America (RSNA) 3D printing Special Interest Group (SIG): guidelines for medical 3D printing and appropriateness for clinical scenarios

Medical three-dimensional (3D) printing has expanded dramatically over the past three decades with growth in both facility adoption and the variety of medical applications. Consideration for each step required to create accurate 3D printed models from medical imaging data impacts patient care and management. In this paper, a writing group representing the Radiological Society of North America Special Interest Group on 3D Printing (SIG) provides recommendations that have been vetted and voted on by the SIG active membership. This body of work includes appropriate clinical use of anatomic models 3D printed for diagnostic use in the care of patients with specific medical conditions. The recommendations provide guidance for approaches and tools in medical 3D printing, from image acquisition, segmentation of the desired anatomy intended for 3D printing, creation of a 3D-printable model, and post-processing of 3D printed anatomic models for patient care.

Bone Marrow Mononuclear Cells Combined with Beta-Tricalcium Phosphate Granules for Alveolar Cleft Repair: A 12-Month Clinical Study

Alveolar cleft is the most common congenital bone defect. Autologous iliac crest bone graft (ICBG) is the most widely adopted procedure for alveolar cleft repair, but the condition is associated with door-site morbidities. For the first time, this study used bone marrow mononuclear cells (BMMNCs) combined with beta-tricalcium phosphate (β-TCP) granules to repair alveolar bone defect. The effectiveness of this technique was compared with autologous ICBG after 12 months of follow-up. The bone formation volume was quantitatively evaluated by three-dimensional computed tomography and computer aided engineering technology. BMMNCs/β-TCP granule grafting was radiographically equivalent to ICBG in alveolar cleft repair. Although considerable resorption was observed up to 6 months after surgery, no significant differences were noted in the Chelsea score and bone formation volume between groups. These finding indicate that BMMNCs/β-TCP grafting is a safe and effective approach for alveolar bone regeneration.