Steven Lai

Simple technique to achieve a natural head position for cephalography.

The cephalometric measurement of the face in terms of aesthetics can be difficult and misleading due to the variability of the intra-cranial reference lines according to diversity of head posture. Natural head position (NHP) has been proposed as a preferred reference position for assessing facial morphology. Even though natural head position is more proper and valid, it is still abandoned by reasons of time-consumption and additional and necessary complex equipment. Hence, we developed a modified level laser approach to acquire the natural head position. This method was a simple and straightforward technique which may be of value as and adjunct to routine orthognathic planning.

Correlation between the change of gonial region and skeletal relapse after intraoral vertical ramus osteotomy for correction of mandibular prognathism.

Background: The gonial region is coincided with harmonious face and masticatory function. The aims of the present study were to assess changes in the gonial region in patients who had mandibular setback surgery by intraoral vertical ramus osteotomy (IVRO) and to investigate the contributing factors in relation to skeletal relapse. Methods: Twenty-one patients with mandibular prognathism were corrected by IVRO. Three cephalometric radiographs were collected from preoperative orthodontic treatment (T1), immediately after surgery (T2), and at 2-year postoperative follow-up (T3). Relapse was defined as forward movement of menton (Me) after the 2-year follow-up. Three angular (SN-Go angle, mandibular plane angle, and gonial angle) and 2 linear (horizontal-Me and vertical-Me) measurements were compared after immediate operation and at the 2-year follow-up. Spearman rank correlation and Student t tests were used for statistical analysis. Results: The mean setback of the Me was 12.7 mm, and the mean relapse was 1.5 mm. The magnitude of setback was not significant for relapse. There were weak correlations between relapse and factors concerned with the gonial region (SN-Go angle, mandibular plane angle, and gonial angle). Conclusions: Surgical correction of mandibular prognathism using IVRO can lead to an increase in the angle changes of gonial region but not correlate to skeletal relapse in long-term follow-up.

Intraoperative Hemorrhage and Postoperative Sequelae after Intraoral Vertical Ramus Osteotomy to Treat Mandibular Prognathism

Objective. To investigate the factors affecting intraoperative hemorrhage and postoperative sequelae after orthognathic surgery. Materials and Methods. Eighty patients with mandibular prognathism underwent surgical mandibular setback with intraoral vertical ramus osteotomy (IVRO). The correlation between the blood loss volume and postoperative VAS with the gender, age, and operating time was assessed using the t-test and Spearman rank correlation coefficient. The correlation between the magnitude of mandibular setback with the presence of TMJ clicking symptoms and lip sensation was also assessed. Results. The mean operating time and blood loss volume for men and women were 249.52 min and 229.39 min, and 104.03 mL and 86.12 mL, respectively. The mean VAS in men and women was 3.21 and 2.93, and 1.79 and 1.32 on the first and second postoperative days. There is no gender difference in the operating time, blood loss, VAS, TMJ symptoms, and lip numbness. The magnitude of mandibular setback was not correlated with immediate and long-term postoperative lip numbness. Conclusion. There are no gender differences in the intraoperative hemorrhage and postoperative sequelae (pain, lip numbness, and TMJ symptoms). In addition, neither symptom was significantly correlated with the amount of mandibular setback.

Soft-tissue profile changes after orthognathic surgery of mandibular prognathism

During surgical correction of facial deformities, accurate prediction of the resulting facial profile is important for the patient and the surgeon. The purpose of the present study was to investigate profile changes after surgical treatment of mandibular prognathism. Thirty patients (20 females and 10 males; ages 17–28 years) with mandibular prognathism underwent vertical ramus osteotomy. Preoperative and postoperative cephalograms were analyzed; landmarks were identified and compared. The mean horizontal setback of the pogonion (Pog) was 11.7 mm. The setback ratios of labrale inferius (Li)/incision inferius (Ii), labiomental sulcus (Si)/point B, and soft tissue pogonion (PogS)/pogonion (Pog) were 0.98, 0.99, and 0.95, respectively. There were no sex‐related changes in soft tissue. These findings indicate that changes in soft tissue closely correlate with the amount of mandibular setback in the horizontal direction. Such information might facilitate more accurate prediction of the outcome of orthognathic surgery.

Correlation Between Blood Loss and Patient-Related Factors in the Bilateral Parasymphyseal Osteotomy.

AbstractThe aim of this study was to determine the correlation between pre- and postsurgical loss of blood and blood components among patients undergoing treatment of facial deformities by bilateral parasymphyseal osteotomy (BPsO).The pre- and postoperative values of blood components were determined in 30 facial deformity patients who underwent orthognathic surgery by hypotensive anesthesia.Correlations among the blood loss, sex, age, operation time, and reduced values of blood components were assessed by a correlation matrix.The mean blood loss and operation time were 437.5 (±52.5) mL and 355.8 (±209.42) minutes, respectively. Two patients included in this study had required blood transfusion. The mean reduced red blood cell (×106/&mgr;L), hemoglobin (g/dL), and hematocrit (%) were −1.02, −2.98, and −9.18, respectively. There was no significant correlation between blood loss and other related factors (eg, age, operation time, and reduced blood components). All patients, however, showed significantly lower values of blood components after surgery.In conclusion, no significant factor was associated with blood loss and reduced blood components among patients undergoing BPsO. Furthermore, hypotensive anesthesia is a well-accepted method to reduce blood loss during orthognathic surgery.

Correlation between the Pharyngeal Airway Space and Head Posture after Surgery for Mandibular Prognathism

Purpose. The aim of this study was to determine the correlation between the pharyngeal airway space and head posture after mandibular setback surgery for mandibular prognathism. Materials and Methods. Serial lateral cephalograms of 37 patients with mandibular prognathism who underwent intraoral vertical ramus osteotomy (IVRO) were evaluated before (T1) and immediately (T2), between 6 weeks and 3 months (T3), and more than 1 year (T4) after surgery. Paired t-tests and Pearsons correlation analysis were used to evaluate the postoperative changes in all cephalometric parameters, including the mandible, hyoid, head posture (craniocervical angle), and pharyngeal airway space. Results. The mandible and hyoid were set back by 12.8 mm and 4.9 mm, respectively, at T2. Furthermore, the hyoid showed significant inferior movement of 10.7 mm, with an 8 mm increase in the tongue depth. The upper oropharyngeal airway (UOP) shortened by 4.1 mm, the lower oropharyngeal airway (LOP) by 1.7 mm, and the laryngopharyngeal airway by 2 mm. The craniocervical angle showed a significant increase of 2.8°. UOP and LOP showed a significant correlation with the craniocervical angle at T2 and T4. Conclusions. Our findings conclude that the oropharyngeal airway space is significantly decreased and correlated with a change in the head posture after mandibular setback surgery.

Effects of patient- and operation-related factors on postoperative pain after orthognathic surgery.

Purpose This study aimed to assess the association between patient- and operation-related factors and postoperative pain in patients undergoing intraoral vertical ramus osteotomy (IVRO) or IVRO + genioplasty (GeP) for the treatment of mandibular prognathism. Materials and Methods A visual analog scale (VAS) was used to evaluate postoperative pain for 2 days in 63 patients who underwent orthognathic surgery (42 IVRO and 21 IVRO + GeP). Correlations between VAS and patient age, sex, blood loss, operation time, and intraoperative reduction in blood parameters were assessed and compared between IVRO and IVRO + GeP procedures. Results Mean operation time and blood loss were 252.02 minutes and 99.64 mL in the IVRO group and 317.62 minutes and 187.86 mL in the IVRO + GeP group, respectively. Operation time, blood loss, and postoperative reduction in blood parameters were significantly greater in the IVRO + GeP group than in the IVRO group. Mean VAS scores on the first and second postoperative days were 3.02 and 1.33 in the IVRO group and 2.95 and 1.14 in the IVRO + GeP group. However, postoperative pain did not differ significantly between the IVRO and IVRO + GeP groups on the first or second postoperative day. Conclusions Postoperative pain associated with orthognathic surgery was acceptable, controllable, and not different between IVRO and IVRO + GeP procedures.

Changes in the transverse dimensions by vertical ramus osteotomy after mandibular prognathism correction.

Objective: A harmonious face displays not only a good lateral profile but also a pleasant frontal appearance. The purpose of the current study was to evaluate the changes in the transverse dimensions by vertical ramus osteotomy (VRO) in the treatment of mandibular prognathism correction. Methods: Twenty patients who underwent mandibular prognathism correction by VRO were included. Lateral and frontal cephalometric radiographs were obtained at the following stages: preoperative (T1), immediately after the surgery (T2), and completion of orthodontic treatment (T3). Three linear measurements (menton, intercondylion, and intergonial distances) and the ramus angle were compared from T1 to T3. Results: A final mean menton setback of 12.2 mm and upward movement of 0.3 mm were noted. The intercondylion and intergonial distances significantly increased by 5.1 and 7.1 mm, respectively. Without significant difference, ramus angles decreased 1.7 degrees in the right side and 0.1 degrees in the left side. Conclusion: The surgical correction of mandibular prognathism using VRO led to an increase in the transverse dimensions.

Eye patch sandwich technique for stabilizing the intraoral skin graft to the cheek.

It is very important to secure skin graft in the defect of oral cavity. The tie-over bolster technique is the most common method for securing intraoral skin grafts. However, gauze is the best material as a bolster that can easily accumulate saliva and debris and cause odor and discomfort to the patient. We describe an alternative technique to stabilize intraoral skin graft between 2 aluminous eye patches and to readily keep the oral hygiene during the securing period.

Are Hyoid Bone and Tongue the Risk Factors Contributing to Postoperative Relapse for Mandibular Prognathism

Objective. The purpose of this study was to investigate postoperative stability and the correlation between hyoid, tongue, and mandible position following surgery for mandibular prognathism. Materials and Methods. Thirty-seven patients, treated for mandibular prognathism using intraoral vertical ramus osteotomy (IVRO), were evaluated cephalometrically. A set of four standardized lateral cephalograms were obtained from each subject preoperatively (T1), immediately postoperatively (T2), six weeks to three months postoperatively (T3), and more than one year postoperatively (T4). The Student t-tests, the Pearson correlation coefficient, and the multiple linear regression were used for statistical analysis. Results. Immediately after surgery, menton (Me) setback was 12.8 mm, hyoid (H) setback was 4.9 mm, and vallecula epiglottica (V) setback was 5.8 mm. The postoperative stability significantly correlated (r = −0.512, p < 0.01) with the amount of setback. The hyoid bone and tongue did not have significant effects on postoperative stability. Multiple linear regression model (R 2 = 0.2658, p < 0.05) showed predictability: Horizontal Relapse Me (T4-T2) = −6.406 − 0.488Me (T2-T1) + 0.069H (T2-T1) − 0.0619V (T2-T1). Conclusion. Mandibular setback surgery may push the hyoid and tongue significantly backward, but this did not correlate with mandibular relapse. Postoperative stability significantly correlated with the amount of mandibular setback.