One-Stage treatment for maxillofacial asymmetry with orthognathic and contouring surgery using virtual surgical planning and 3D-printed surgical templates

Modeling Methods in Craniofacial Virtual Surgical Planning

Despite the widespread use of virtual surgical planning (VSP), few papers describe the modeling methods used to generate the digital simulations that underpin VSP. This paper aims to review the modeling methods that are currently available for use in VSP and the implications of their use in clinical practice. A literature review was undertaken of the two broad categories of modeling techniques; contour-based planning-namely mirroring from the contralateral side, templating from a normative database, and extrapolation from surrounding landmarks-and occlusal-based planning (OBP). The indications for each modeling method were discussed, including mandibular/maxillary reconstruction, pediatric craniofacial surgery, and orthognathic, as well as the limitations to the accuracy of modeling types. Unilateral defects of the upper/midface, wherein contour accuracy is paramount, are best reconstructed using mirroring methods, whereas bilateral defects-or cases with asymmetry due to craniofacial dysmorphology-are most suited to normative-data-based methods. Cases involving resection of the alveolar margin, in which functional occlusion is the primary outcome are best managed with OBP. Similarly, orthognathic surgery typically uses OBP, although complex cases involving asymmetry, such as clefts, may benefit from a combination of OBP and normative data methods. The choice of modeling methods is, therefore, largely driven by the defect type and the goals of reconstruction.

Simultaneous Fat Injection for Nasal Contouring in Orthognathic Patients

BACKGROUND

Augmentation rhinoplasty with autologous fat grafting is a useful procedure to meet the demand for facial harmonization in the Asian population. We used this procedure during orthognathic surgery to address inadequate dorsum projection. This prospective study was conducted to determine the fat retention rate in patients undergoing simultaneous autologous fat injection augmentation rhinoplasty and orthognathic surgery.

METHODS

Nineteen patients were treated with simultaneous bimaxillary orthognathic surgery and autologous fat grafting of the nasal dorsum and tip. The paired t test was used to compare the nasal volumes before and at least 6 months after surgery measured by 3-dimensional computer tomography scans. All measurements were performed twice by the same evaluator at least 2 weeks apart for intrarater consistency.

RESULTS

Seventeen patients completed the study. The volume means before and after surgery were 22.3 ± 4.6 cm³ and 23.3 ± 4.7 cm³, respectively, with a mean difference of 1.0 ± 0.3 cm³ (P < .001). The mean retention rate was calculated to be 50.5% ± 7.0% (range: 40.5%-64.7%). Intrarater consistency was high with a Cronbach α of .97 (P < .001) and .98 (P < .001), respectively.

CONCLUSION

This prospective study provides objective graft retention measurements for fat injection augmentation rhinoplasty combined with orthognathic surgery. All patients were satisfied with the results and no complications or additional morbidity was noted in the postoperative course. We consider this procedure to be a safe, reliable, and powerful adjunct to improve the aesthetic results of orthognathic surgery.

Three-dimensional comparative evaluation of customized bone-anchored vs tooth-borne maxillary protraction in patients with skeletal Class III malocclusion

INTRODUCTION

The aim of this prospective study was to assess the 3-dimensional skeletal and dental effects induced by a new maxillary protraction approach using customized miniplates for anchorage compared with a control group of traditional tooth-borne maxillary protraction.

METHODS

Forty-one growing patients at prepubescent stage with skeletal Class III malocclusion participated in this study. These patients were randomly split into 2 groups. In group 1 (n = 20), patients underwent maxillary protraction anchored with customized miniplates. The miniplates were individually designed and inserted using the surgical templates. In group 2 (n = 21), patients underwent tooth-borne maxillary protraction. Pretreatment and posttreatment cone-beam computed tomography scans were obtained, and 30 measurements of cone-beam computed tomography images were acquired and calculated. The changes after treatment and the comparison of the 2 groups were assessed.

RESULTS

After maxillary protraction, group 1 showed a greater forward movement of the maxilla than group 2. The maxilla length increased more in group 1 than in group 2. The rotations of the palatal and mandibular planes in group 1 were less than those in group 2. In group 1, the maxillary incisors proclined less, the mandibular incisors retroclined less, and the maxillary first molars extruded less.

CONCLUSIONS

Compared with tooth-borne maxillary protraction, customized miniplates anchored maxillary protraction produced more maxillary growth, fewer dental changes, and less maxillary and mandibular plane rotation.

A digital photograph study evaluating facial taperness and square face perception of Taiwanese females

BACKGROUND

This study assessed the perception of facial taperness in Taiwanese females among people with dental knowledge and laypersons. Additionally, this study also specified the criteria by which "square face" was defined regarding Taiwanese females' facial taperness.

METHODS

A series of digitally modified photos with different levels of facial taperness (Gonion to Gonion/Zygoma point to Zygoma point-Go-Go/Zy-Zy ratio ranges from 65% to 90%) were randomly arranged and presented to the raters. Visual analog scale (VAS) lines were used for scoring the photos on a scale of 0-100. The true or false question about "defining square face" was incorporated in the same questionnaire. The reliability of the true/false square face question and the esthetic evaluation by VAS were assayed. The receiver operating characteristic curve was used to define the cutoff point on "square face." The effects on the raters' genders, orthodontic treatment experience, and their professional background on the perception of a square face were assayed.

RESULTS

The overall reliability of the raters was within the acceptable range. The VAS score evaluation revealed that the average expectation for best facial taperness was 75%, whereas the facial taperness of over 83% was considered as the square face. The facial taperness reaching to 90% was regarded as the most unattractive. Gender, therapy, and professional experience have no impact on the standard of square facial form evaluation.

CONCLUSION

A face with a taperness greater than 83% was evaluated as a square face, and a face with a taperness around 75% was considered as the most attractive.

Application of Virtual Planning for Three-Dimensional Guided Maxillofacial Reconstruction of Pruzansky-Kaban III Hemifacial Microsomia Using Custom Made Fixation Plate

PURPOSE

Pruzansky-Kaban III hemifacial microsomia (HFM) is a rare congenital facial deformity, and it is challenging to reconstruct the facial appearance. The aim of the present study was to describe a technique of application of virtual planning for three-dimensional (3D) guided maxillofacial reconstruction of Pruzansky-Kaban III HFM using custom made fixation plate.

METHODS

With the help of 3D models, a preoperative virtual planning and surgical simulation were performed. Computer-aided design/computer-aided manufacture (CAD/CAM) patient customized guides and custom fixation plates were designed to reconstruct the maxillofacial skull intraoperatively. Assessment was achieved through evaluation of the postoperative effects, such as imaging, facial appearance recovery and operation time.

RESULTS

Five patients with Pruzansky-Kaban III HFM were enrolled into this study. The results showed an exceptional accuracy between the preoperative virtual planning and the outcomes actually achieved postoperatively. Intraoperative measurements were no longer needed and the different surgical steps became more simple and easier. The total time was distributed as: 160 minutes for the surgical time, 40 minutes for preoperative virtual plan, and 80 minutes for designing the patient specific cutting guides and custom fixation plates. The operating time and tissue damage were reduced. All cases underwent uneventful healing without any complications.

CONCLUSION

The technique of patient specific guides and custom fixation plates is a reliable method of conveying the virtual plan to the operative field with higher efficiency in patients with Pruzansky-Kaban III HFM.

Dental 3D-Printing: Transferring Art from the Laboratories to the Clinics

The rise of three-dimensional (3D) printing technology has changed the face of dentistry over the past decade. 3D printing is a versatile technique that allows the fabrication of fully automated, tailor-made treatment plans, thereby delivering personalized dental devices and aids to the patients. It is highly efficient, reproducible, and provides fast and accurate results in an affordable manner. With persistent efforts among dentists for refining their practice, dental clinics are now acclimatizing from conventional treatment methods to a fully digital workflow to treat their patients. Apart from its clinical success, 3D printing techniques are now employed in developing haptic simulators, precise models for dental education, including patient awareness. In this narrative review, we discuss the evolution and current trends in 3D printing applications among various areas of dentistry. We aim to focus on the process of the digital workflow used in the clinical diagnosis of different dental conditions and how they are transferred from laboratories to clinics. A brief outlook on the most recent manufacturing methods of 3D printed objects and their current and future implications are also discussed.

Skeletal stability after 2-jaw surgery via surgery-first approach in facial asymmetry patients using CBCT

BACKGROUND

The purpose of this study is to compare the skeletal stability of two-jaw surgery via surgery-first approach with conventional two-jaw surgery in facial asymmetry patients by measuring the skeletal changes after surgery from a three-dimensional analysis. From January 2010 to January 2014, 40 patients with facial asymmetry who underwent two-jaw surgery in Pusan National University Hospital were included in this study. They were classified into experimental group (n = 20) who underwent two-jaw surgery via surgery-first approach and control group (n = 20) who underwent conventional two-jaw surgery. After selection of 24 landmarks and the construction of horizontal and sagittal, coronal reference planes, changes in 10 linear measurements and 2 angular measurements were compared between the surgery-first approach and conventional groups in the preoperative, immediate postoperative, and postoperative periods. The paired t test and Student t test were used for statistical analysis. The mean and standard deviation of the measurement were calculated for the experimental and control groups.

RESULTS

The statistical analysis showed that changes in skeletal measurements were similar between the surgery-first approach and conventional groups, according to each period. However, U1-SRP measurement showed statistically significant changes in surgery-first approach groups at postsurgical change (T1 to T2). Also, the mean treatment duration in the treatment group was 15.9 ± 5.48 months whereas that in the control group was 32.9 ± 14.05 months.

CONCLUSION

In facial asymmetry patients, similar results were observed in the postoperative skeletal stability when 2-jaw surgery via surgery-first approach was compared with conventional 2-jaw surgery. However, significant lateral deviation of upper incisor midline was observed. In addition, a shorter average treatment duration was observed. To stabilize the unstable occlusion after surgery, increased wearing of the stent and proactive rubber guidance will be needed.

Type of maxillary segment mobilization affects three-dimensional nasal morphology

BACKGROUND

Surgical mobilization of the maxillary segment affects nasal morphology. This study assessed the impact of the type of maxillary mobilization on the three-dimensional (3D) nasal morphometry.

METHODS

Pre- and postsurgery cone beam computed tomography-derived facial image datasets of consecutive patients who underwent two-jaw orthognathic surgery were reviewed. Using preoperative 3D facial models as the positional reference of the skeletal framework, 12-month postoperative 3D facial models were classified into four types of maxillary mobilizations (advancement [n = 83], setback [n = 24], intrusion [n = 55], and extrusion [n = 52]) and four types of final maxillary positions (anterosuperior [n = 44], anteroinferior [n = 39], posterosuperior [n = 11], and posteroinferior [n = 13]). Six 3D soft tissue nasal morphometric parameters were measured, with excellent intra- and interexaminer reliability scores (ICC>0.897) for all the measurements. The 3D nasal change for each nasal parameter was computed as the difference between postoperative and preoperative measurement values.

RESULTS

The intrusion maxillary mobilization resulted in a significantly (all p<0.05) larger 3D nasal change in terms of alar width, alar base width, and nostril angle parameters, and a smaller change in terms of the nasal tip height parameter than the extrusion maxillary mobilization; however, no significant (all p>0.05) difference was observed between advancement and setback maxillary mobilizations. The anterosuperior and posterosuperior maxillary positions had a significantly (all p<0.05) larger 3D nasal change in terms of the alar base width and nostril angle than the anteroinferior and posteroinferior maxillary positions.

CONCLUSION

The type of maxillary mobilization affects the 3D nasal morphometry.

Do patient-specific cutting guides and plates improve the accuracy of maxillary repositioning in hemifacial microsomia?

The aim of this retrospective study was to use computer-aided design and manufacturing (CAD/CAM) patient-specific plates and cutting guides for the waferless positioning and fixation of the maxilla after bimaxillary osteotomies in cases of hemifacial microsomia with condylar dysplasia or absence of the temporomandibular joint (TMJ), and to compare the results with the CAD/CAM fabricated surgical wafer by 3-dimensional analysis. Eighteen patients were selected from the hospital database, preoperative surgical planning and simulation were done on 3-dimensional computed tomographic models for all patients, and they were divided into Group I - in which CAD/CAM patient-specific cutting guides and plates were used; and Group II - in which CAD/CAM fabricated surgical wafers were used. Finally, the outcome was evaluated by comparing planned with postoperative outcomes. The largest discrepancies of the Le Fort I segment were 0.50 (0.18) mm in the anteroposterior direction and 0.82 (0.60)° in the yaw orientation with Group I. The largest discrepancies of the Le Fort I segment were 1.32 (1.40) mm in superioinferior direction and 8.48 (7.73)° in the yaw orientation with Group II. The CAD/CAM patient-specific cutting guides and plates proved to be reliable and have great value in improving the accuracy in repositioning the Le Fort I segment and in the efficacy of orthognathic treatment of hemifacial microsomia with condylar dysplasia or no TMJ. The CAD/CAM patient-specific cutting guides and plates are therefore a useful alternative to the wafer technique.

Generative Noise Reduction in Dental Cone-Beam CT by a Selective Anatomy Analytic Iteration Reconstruction Algorithm

Dental cone-beam computed tomography (CBCT) is a powerful tool in clinical treatment planning, especially in a digital dentistry platform. Currently, the “as low as diagnostically acceptable” (ALADA) principle and diagnostic ability are a trade-off in most of the 3D integrated applications, especially in the low radio-opaque densified tissue structure. The CBCT benefits in comprehensive diagnosis and its treatment prognosis for post-operation predictability are clinically known in modern dentistry. In this paper, we propose a new algorithm called the selective anatomy analytic iteration reconstruction (SA2IR) algorithm for the sparse-projection set. The algorithm was simulated on a phantom structure analogous to a patient’s head for geometric similarity. The proposed algorithm is projection-based. Interpolated set enrichment and trio-subset enhancement were used to reduce the generative noise and maintain the scan’s clinical diagnostic ability. The results show that proposed method was highly applicable in medico-dental imaging diagnostics fusion for the computer-aided treatment planning, because it had significant generative noise reduction and lowered computational cost when compared to the other common contemporary algorithms for sparse projection, which generate a low-dosed CBCT reconstruction.

Virtual Surgical Planning and One-Stage Treatment of Active Hemimandibular Hyperplasia

Hemimandibular hyperplasia was first described in 1836 by Adams as a disorder that causes condylar hyperplasia, deforming facial asymmetry and has an unknown etiology. The objective of this study was to report a patient with surgical correction through orthognathic surgery and high condilectomy for the treatment of hemimandibular hyperplasia. The patient complained of pain and cracking in the right temporomandibular joint region and was dissatisfied with the aesthetic appearance of the face. Virtual planning was done for bimaxillary orthognathic surgery and preparation of prototyped surgical guides. Stereolithographic models were used for the preparation of the acrylic guides of the osteotomies for the high condilectomy and the contour of the mandibular base. Orthognathic surgery resulted in the maxillary repositioning with correction of the inclination of the occlusal plane, reduction of the height of the ramus and right mandibular body and class I dental attachment. Mandibular contour osteotomy was performed with acrylic guide in the basilar. The condilectomy was performed by endaural access. In 2-year follow-up, there are no signs of recurrence.

The Use of Virtual Surgical-Guided Osteoplasty for Maxillofacial Brown Tumors

A 28-year-old African American female with end-stage renal disease on dialysis secondary to preeclampsia presented to the office as a referral for large multifocal tumors of maxilla and mandible. Surgical pathology and laboratory findings were supportive of secondary hyperparathyroidism leading to multifocal brown tumors. She underwent osteoplasty after using virtual surgical planning to create stereolithic models to visualize the tumor and fabricate cutting guides to minimize the risk of injury to adjacent nerves and teeth. Brown tumors can be resistant to medical management with unreliable regression in size. With the advent of customized surgical guides, more precise and judicious surgery can be performed on these types of tumors safely.