Jaw Deformity Patients Research Articles

Relationship between condylar surface CT value in coronal plane and condylar morphology in jaw deformity patients

Objectives. This study aimed to examine the relationship between condylar surface computed tomography (CT) values in the coronal plane and condylar morphology in patients with jaw deformities classes II and III before and after orthognathic surgery. Materials and MethodsThe maximum CT values (pixel values) at three points on the condylar surface, height, and joint space were measured on the coronal plane. The condylar width, thickness, and angle were measured on the horizontal plane preoperatively and at 1 year postoperatively. ResultsA total of 112 temporomandibular joints of 56 female patients were divided into two groups according to skeletal class (56 joints each in class II and class III). The maximum CT values of class II were higher than those of class III at the medial, central, and lateral sites on the condylar surface, preoperatively and at 1 year postoperatively (P < 0.05). CT values of the condylar surface were significantly negatively correlated with the condylar heights at the center and lateral sites preoperatively and at 1 year postoperatively (P < 0.05). ConclusionsCondylar surface CT values in the coronal plane are associated with condylar morphology, including condylar height.

Incidental findings on preoperative head and neck MRI for orthognathic surgery in jaw deformity patients

ObjectiveImaging is a critical component of orthognathic treatment. Magnetic resonance imaging (MRI) is a non-invasive method for observing the temporomandibular joint (TMJ). At our institution, MR images of the TMJ are also used when planning treatment for jaw deformities, head and neck screening images are also acquired using a head coil during MR imaging of the TMJ to confirm the presence of incidental findings (IFs) of head and neck lesions. IFs may require additional examination and/or treatment, even if the lesion is asymptomatic. This article presents a review of diseases detected as IFs during MR imaging. Case reports are also presented in which the detection of an IF affected the management of the jaw deformity. MethodsReports of 401 patients with jaw deformities who underwent TMJ MR imaging including head and neck screening before preoperative orthodontic treatment were retrospectively reviewed. ResultsAsymptomatic IFs were detected in 89 patients on screening images performed simultaneously with the TMJ MR imaging. The most common site was the maxillary sinus, and the most common lesions were inflammatory lesions. Although most of the IFs were not clinically significant, 10 required treatment prior to orthognathic treatment or required more detailed examination. ConclusionsAlthough small in number, some of the IFs detected in this study required the use of non-conventional treatment strategies. Our approach of combining TMJ MR imaging with head and neck screening assists not only in evaluating the TMJ but also in detecting lesions that are difficult to detect in radiographic images.

Changes in nutritional status of patients with jaw deformities due to orthognathic surgery

In orthognathic surgery, it is important to carefully manage peri-operative nutrition because maxillomandibular fixation and problems such as swelling and pain after surgery may make it difficult to eat normally and may prevent adequate nutrition. This study investigated the changes in nutritional status of patients with jaw deformities due to orthognathic surgery. The subjects were 155 jaw deformity patients, who underwent orthognathic surgery. The nutritional status was evaluated using anthropometry immediately before and 10 days after surgery and clinical laboratory results and the controlling nutritional status (CONUT) score before surgery and immediately, 1 week and >6 months after surgery. We investigated the relationship among the nutritional status, surgical procedures, and dietary intake in patients who underwent orthognathic surgery. The surgical procedure time and amount of bleeding were significantly greater as the surgical procedure became more complex. All of the laboratory values and CONUT scores were significantly decreased immediately after surgery and then increased over time, recovering to the same level as before surgery except for serum albumin at >6 months after surgery. Nutritional management is considered as one of the key factors for the better and faster recovery after the orthognathic surgery.

A three-dimensional cephalometric analysis of Japanese adults and its usefulness in orthognathic surgery: A retrospective study

This study aimed to establish a three-dimensional (3D) cephalometric analysis of craniofacial morphology and discuss its theoretical usefulness in orthognathic patients.Cone-beam computed tomography (CBCT) images of Japanese subjects with skeletal Class I malocclusion before treatment were selected from among 1000 patients so that samples matched a historic 2D cephalometric cohort with normal occlusion using propensity score matching. In each CBCT image, 67 3D measurements were calculated based on manually identified landmarks. The mean and standard deviation of the measurements were calculated and used as the normative range for each sex. To confirm the usefulness of the 3D measurements, pre- and post-treatment CT data of nine jaw deformity patients who underwent orthognathic surgery with two-dimensional planning (2DP) in the past were used. Pre- and post-treatment CT values were evaluated with a paired t-test as well as a Z-score, which was calculated using the aforementioned normative range, and then categorized into five groups (“deteriorated”, “no improvement”, “over-treatment”, “no change”, “improvement”) with −1 < Z-score < 1 considered normal.Fifty-six patients were matched to normal skeletal 1 subjects. The normative range of 67 items indicating 3D craniofacial morphology of the Japanese was calculated. Postoperatively, the horizontal position of the pogonion to the mid-sagittal plane significantly decreased (p = 0.043) and “improved”; however, the ramus axis on the right side significantly increased (p = 0.005) and “deteriorated”. Maxillary yaw and the horizontal position of the gonion also tended to “deteriorated”.The normative range for the 3D cephalometric analysis in Japanese has been established. Given findings of deteriorated maxillomandibular yawing after surgery when using conventional 2DP, 3D cephalometric measurements should be used when planning jaw positions after surgery for orthognathic patients.

Establishment of a new rehabilitation program using masticatory training food for jaw deformity patients

Background/purposePatients with jaw deformities may show a reduction in masticatory function as a result of postoperative hypofunction. This study aimed to establish a novel rehabilitation program using a commercially available masticatory training food for patients with jaw deformities after orthognathic surgery. Materials and methodsNine patients with mandibular prognathism (the training group: n = 5, and the non-training group: n = 4) and 6 control participants with normal occlusion were included in this study. For the rehabilitation program with masticatory exercise, patients were instructed to chew the training food once a day for 60 days starting from 10 days after the surgery. The effects of the rehabilitation program were assessed by determining the maximum bite force (MBF) and the masticatory performance (MP). Clinical assessments were performed just before orthognathic surgery (Pre) and at 10 days (T0), 1 month (T1), 2 months (T2), and 3 months (T3) after surgery. ResultsCompared with the non-training group, the training group showed a trend toward greater recovery amount of MBF from Pre to T3, and a significantly greater recovery amount in MP (p < 0.05) from Pre to T3. When the time-series change of MP was evaluated in both groups from T0 to T3, a significant difference was observed in the interaction terms (p = 0.03). This result indicates that the effectiveness of the training may be demonstrated by following the postoperative course further. ConclusionThe rehabilitation using this training food may become a useful method for postoperative hypofunction in patients with jaw deformities.

Evaluation of condylar surface CT values related to condylar height reduction after orthognathic surgery

This study was performed to evaluate the relationship between condylar height reduction and changes in condylar surface computed tomography (CT) values in jaw deformity patients following orthognathic surgery.Mandibular advancement by sagittal split ramus osteotomy (SSRO) with Le Fort I osteotomy was performed in class II patients, and mandibular setback by SSRO with Le Fort I osteotomy was performed in class III patients. The maximum CT values (pixel values) at five points on the condylar surface and the condylar height, ramus height, condylar square, ramus angle, and gonial angle in the sagittal plane were measured preoperatively and 1 year postoperatively. Disc position was classified as anterior disc displacement (ADD) or other types by using magnetic resonance imaging (MRI).Ninety-two condyles of 46 female patients were prepared for this study. Their temporomandibular joints (TMJs) were divided into two groups based on class (46 joints in class II and 46 joints in class III) and two groups based on the findings (25 joints with ADD and 67 joints with other findings). ADD with and without reduction was observed in two joints in the class III group and in 23 joints in the class II group. The distribution of ADD incidence had not changed 1 year after surgery. Condylar height decreased 1 year after surgery in both class II patients (mandibular advancement) (p < 0.0001) and class III patients (mandibular setback) (p = 0.0306). Similarly, condylar height decreased 1 year after surgery both in patients who showed ADD (p = 0.0087) and those with other types (p = 0.0023). Significant postoperative increases at all angle sites on the condylar surface were found in the class II (p < 0.05) and ADD (p < 0.05) groups.This study showed that an enhanced condylar surface CT value might be one sign of condylar height reduction related to sequential condylar resorption, in combination with ADD.

Current status of clinical orthodontics in European and American countries

Current status of clinical orthodontics in European and American countries was examined by means of a questionnaire survey through internet. In the European and American countries, most popular technique in daily orthodontic practice is preadjusted straight wire edgewise technique. In major developed countries in Europe and America, the treatment fee is considerably high, whereas the fee is relatively low in the countries under development and/or after economic crisis. Rate of non-extraction treatment among all the cases treated with multi-bracket appliances is significantly higher in Europe and America than in Asia except in a few countries. In the European and American countries, treatment system for jaw deformity patients is well developed with higher availability of the social health insurance than in Asia. The maximum CLP prevalence of 0.200 is found in Germany and Austria and the mean is around 0.140 or one to 700 births. In general, CLP treatment is covered by social health insurance in European and American countries. In Europe and America, lingual orthodontic technique has not become popular because patients never want to hide orthodontic appliance. Higher cost of lingual appliance and lack in information and technical skills may be the reasons of less frequent use of lingual appliance. Many interviewees replied that usage of TADs has not become so popular in USA and Canada as compared to that in Asia. In another word, the initial fascination with TADs wore off and are now used in selected patients as needed. This may be due to more harmonious maxillofacial structure with longer and wider dentitions in Caucasians which also results in higher rate of non-extraction treatment with multibracket appliances in European and American countries.

Evaluation of border movement of the mandible before and after orthognathic surgery using a kinesiograph

PurposeThe purpose of this study was to examine the changes in the mandibular border movement between class II and class III jaw deformity patients before and after orthognathic surgery, by using the same device. Subjectsand Methods: Eighty one patients (28 in class II and 53 in class III) who underwent sagittal split ramus osteotomy (SSRO) with Le Fort I osteotomy using absorbable plate fixation and 27 controls with normal occlusion were enrolled. Mandibular border movement (observed using a kinesiograph) was recorded with a mandibular movement measure system (K7) before surgery, and at 6 months and 1 year after surgery. Time-course changes of 5 components of the mandibular border movement (MVO: Maximum vertical opening, CO to MAP: Maximum antero-posterior movement from centric occlusion, MLDL: maximum lateral deviation left, MLDR: maximum lateral deviation right, CO to MO: centric occlusion to maximum opening) were compared between classes II, III and controls statistically. The relationship between lateral cephalometric measurements and the components of mandibular border movement was also examined. ResultsThere was a significant difference in CO to MAP (P = 0.0025) and CO to MO (P < 0.0001) between class II and class III in the time-course change.In class III, mean and standard deviation of MVO were 44.5 ± 6.7 mm before surgery and 39.8 ± 6.8 mm after 1 year. Mean and standard deviation of CO to MAP were 25.2 ± 6.8 mm before surgery and 21.5 ± 7.9 mm after 1 year. Mean and standard deviation of CO to MO were 53.4 ± 9.0 mm before surgery and 47.3 ± 8.4 mm after 1 year.In class II, mean and standard deviation of MVO were 38.8 ± 5.8 mm before surgery and 36.2 ± 7.4 mm after 1 year. Mean and standard deviation of CO to MAP were 18.0 ± 6.3 mm before surgery and 17.8 ± 7.4 mm after 1 year. Mean and standard deviation of CO to MO were 43.1 ± 7.5 mm before surgery and 39.6 ± 10.5 mm after 1 year.In MVO, CO to MAP and CO to MO, the values after 1 year did not significantly reach the pre-operative values in class III (P = 0.0001, P = 0.0007 and P < 0.0001), although there was no significant difference between pre-operation and after 1 year in class II.In CO to MO, class II (mean and standard deviation 39.6 ± 10.5 mm) and class III (mean and standard deviation 47.3 ± 8.4 mm) still remained smaller values than control (mean and standard deviation 52.7 ± 9.2 mm) after 1 year (P < 0.0001 and P = 0.0095). ConclusionThis study suggests that bi-maxillary surgery can have more influence on the reduction in the range of mandibular border movement including vertical or antero-posterior motion than lateral deviation motion, in both groups. The difference in the time-course change in the mandibular border movement between the groups might depend more on the mandibular length than on the movement direction of the mandible by surgery such as advancement or setback.

The measurement of buccal cortical bone thickness with CT images in jaw deformity patients undergoing orthodontic mini‐implants

Background Recently, placement of orthodontic mini-implants (anchor screws) is widely used in orthodontic treatment. One of the anatomical factors affecting the stability of the anchor screws is the bone characteristics (shape, bone mineral density, cortical bone thickness). It is necessary to understand anatomical factors in the area of placement with preoperative diagnostic imaging. Aim/Hypothesis In this study, we measured and evaluated the buccal cortical thickness of the mesio-distal interdental space at the mandibular first molar with multi-detector low computed tomography (MDCT) images of jaw deformity patients. Material and Methods MDCT images of 28 jaw deformity patients participating in the study were acquired and used for the preoperative planning of sagittal split ramus osteotomy (SSRO) surgery. All patients had been previously diagnosed as having an Angle class III malocclusion. After acquisition of MDCT data, all data were transferred to a workstation and evaluated using Zio Cube software (Ziosoft, Inc, Tokyo). The standard plane of all MDCT data was set at the occlusal plane. The cortical thickness on the mesial and distal part of the first molar were measured on the reconstructed cross-sectional images at the level of 5 and 10 mm inferior to the cement-enamel junction (CEJ) on each mesial and distal side. On the same images, the inclination of the mandibular bone was also recorded. The MDCT images were excluded from this study if- (1) Pathological findings were seen in the posterior mandible, and (2) The images were found to exhibit insufficient image quality due to metal artifacts from acquisition. Results Initially, all MDCT images were screened. From these, 5 were excluded according to the exclusion criteria. Thus, a total of 46 sides from 23 patients were used in the analysis. The 23 patients consisted of 15 females and 8 males with a mean age of 22.9 years (range from 18–33 years). The average thickness at the 5 and 10 mm level form the CEJ on the mesial portion of the first molar were 1.44 and 1.91 mm respectively, and on the distal portion were 1.80 and 2.68 mm respectively. Statistical differences were confirmed for buccal cortical thickness at 5 and 10 mm from the CEJ in both the mesial and distal portions of the mandibular first molar. The average lingual inclination of the mandible was by 80.5° n the mesial and 71.2° in the posterior portion. Conclusions and Clinical Implications A detailed understanding of the anatomical characteristics is absolutely critical in maxillofacial surgical procedures, including the placement of anchor screws. To reduce postoperative discomfort, the clinician should be aware of each patient's morphological characteristics.

Current status of orthodontic professionals in the Asian Pacific region

Asian Pacific Orthodontic Society (APOS) was developed in Tokyo on October 1, 2001. Currently, APOS has grown up to a scientific association specified to orthodontics with 18 affiliated societies. However, the status of orthodontic professionals in each society remains unclear beyond our understanding. To this end, I have recently conducted an internet interview to the representatives of affiliated societies. The questionnaire includes the educational system for dentists and orthodontists, the number of orthodontic departments with post-graduate programs, the number of orthodontists or members of each society, orthodontic treatment fee on average, the prevalence of CLP and the treatment, orthodontic treatment for jaw deformity patients, current status of orthodontic treatment with lingual appliances and TADs, important issues for orthodontic specialists, future plans of each society. It is hopefully anticipated that the current status of orthodontic professionals in the Asian Pacific region are well understood by all the APOS members and will become a great benefit for the development of all the affiliate societies.

シンポジウム1：多数歯欠損症を伴う顎変形症患者に対する集学的アプローチ

シンポジウム1：多数歯欠損症を伴う顎変形症患者に対する集学的アプローチ

Relationships between Airway Morphology and Sleep Breathing Indices in Jaw Deformity Patients

Purpose: The purpose of this study was to clarify how sleep breathing indices and airway morphology vary according to skeletal classification and the relationships between airway morphology and sleep breathing indices. Method: Forty-four non-syndromic female Japanese patients, who were diagnosed with jaw deformities and underwent surgical orthodontic treatment were enrolled in this study. Using the Alice 5 diagnostic sleep system (Philips Respironics; Murrysville, PA), the apnea hypopnea index (AHI), apnea index (AI), and 4% oxygen desaturation index (4%ODI) were evaluated in each patient before they underwent orthognathic surgery. The following dimensions were measured on 2D CT images: the cross-sectional area at the level of the hard palate (HP), the cross-sectional area at the top of the uvula (TU), the cross-sectional area at the base of the tongue (BE). The following volumes were measured on 3D CT images: the volume of the upper airway (total volume), the volume of the region between the level of the hard palate and the top of the uvula (HP- TU volume), the volume of the region between the top of the uvula and the base of the epiglottis (TP-BE volume). Result: There were no significant differences in airway morphology or sleep breathing indices among the three groups. Negative correlations were detected between HP-TU volume and 4%ODI, and between the HP area and AHI (p<0.05). Conclusion: Our results establish that upper airway morphology also has important effects on the nocturnal breathing of jaw deformity patients.

DAI Score of Jaw Deformity Patients at Tsurumi University Dental Hospital Department of Orthodontics

DAI Score of Jaw Deformity Patients at Tsurumi University Dental Hospital Department of Orthodontics

新潟大学医歯学総合病院矯正歯科診療室における過去１０年間の外科的矯正治療適用症例の動向

We investigated the trend of patients with jaw deformity in the past decade at Niigata University Medical and Dental Hospital. We also compared the present results with those of our previous report in 2000. The subjects consisted of 525 jaw-deformity patients registered at the Department of Orthodontics, Niigata University Medical and Dental Hospital between January 2000 and December 2009. The number of subjects who underwent orthognathic surgery in our hospital was 767 in the same ten-year period.The items examined were as follows:I. Ratio of jaw-deformity patients to all new outpatients registeredII. Sources which referred jaw-deformity patients to our department and reference rateIII. Annual number of jaw-deformity patients and gender distributionIV. Age of patients at the first examination and at the start of presurgical orthodontic treatmentV. Classification of malocclusion at the first examinationVI. Chief complaints of the patientsVII. Number of orthognathic surgeries and their procedures.The ratio of jaw-deformity patients to all new outpatients registered from 2000 to 2009 was approximately 20%, among whom jaw-deformity patients introduced by other hospitals accounted for 82.1%. Both ratios were slightly higher than in our previous investigation in 2000. In terms of annual changes in jaw-deformity patients, the number of patients tended to decrease after a peak of 75 in 2002, and then slightly increased after 2007. The ratio of males to females was about 1:2. Regarding the age at first examination and the start of presurgical orthodontic treatment, most of the patients involved were from 14 to 19 years old.Mandibular prognathism accounted for 63.5%, which was the most frequent antero-posterior malocclusion in the examined patients. Concerning vertical and horizontal malocclusions, open bite and midline deviation were the most frequent with 25.0% and 48.6%, respectively.As for chief complaints, 55.2% of the complaints concerned malalignment, followed by facial appearance, masticatory disturbance, TMJ disturbance, opinions of other persons, pronunciation disorder, and others. However, the ratio of patients who regarded improvement of the face as one of the chief complaint was very high, at 79.4%, compared with the previous results in 2000.In terms of surgical procedure, two-jaw surgery was the frequent method accounting for 50-65%. It was especially high in 2009 (77.4%).According to the requests of patients, it is considered that two-jaw surgery may increase in the future.

愛知学院大学歯学部附属病院矯正歯科における１０年間の外科的矯正治療患者に関する検討

In order to identify trends among orthognathic surgery patients who visited the Department of Orthodontics at Aichi-Gakuin University Hospital for the 10 years from January 1999 to December 2008, we performed a statistical survey. We examined differences in the maxillofacial morphology of patients with anterior crossbite and maxillary protrusion who had orthognathic surgery or orthodontic treatment.The results were as follows:1. Among a total of 3,065 patients, the number of patients with jaw deformities was 295 (9.6%), comprising 127 (43.1%) male and 168 (56.9%) female patients.2. The average number of patients per year was 29.5.3. Anterior crossbite (147 cases, 49.9%) was the most prevalent condition, followed by anterior crossbite+ open bite (65 cases, 22.0%).4. The average age at diagnosis was 23y5m±7y1m. For males, it was 22y10m±7y0m, and for females, 23y10m±7y0m (mean±S.D.).5. The average ANB for jaw-deformity patients was −3.3±3.1° mandibular protrusion and +7.7±2.7° maxillary protrusion.6. The average overjet for jaw deformity patients was −2.7mm±3.0mm mandibular protrusion and 8.3mm ±3.7mm maxillary protrusion.

P.254 Current perception thresholds in jaw deformity patients

P.254 Current perception thresholds in jaw deformity patients

顔面非対称を伴う下顎前突症患者における顎骨非対称の三次元評価

The present study was designed to three-dimensionally evaluate the morphological asymmetry of maxillofacial complexes such as the maxilla and the mandible, and the state of the maxillary and mandibular deviation in the craniofacial complex of jaw-deformity patients with facial asymmetry. Based upon the results obtained, we tried to classify the states of asymmetry and/or deviation in the cases showing diverted jaw.The subjects comprised 15 patients (10 males and 5 females; 16 years and 6 months old on average) diagnosed as mandibular prognathism with facial asymmetry. All subjects exhibited more than 4-mm deviation of the mandible from the midline on the frontal cephalogram. Pretreatment CT images were taken as data for precise diagnosis in all subjects. Then, sliced CT data were forwarded to 3D reconstruction software Medical Viewer INTAGE 3.1 in order to form the MPR images. After that, 3D-CT images were constructed using the volume rendering (VR) method. After these images were obtained, the three-dimensional ratio of morphological asymmetry of the maxilla and the mandible was analyzed. The three-dimensional ratio of the maxillary and mandibular deviation was also examined.As a result, various types of asymmetry and/or deviation existed and the cases examined were divided into the following eight types: 1. Symmetrical maxilla without deviation in the craniofacial complex, 2. Almost symmetrical maxilla with deviation in the craniofacial complex, 3. Asymmetrical maxilla without deviation, 4. Asymmetrical maxilla with deviation, 5. Asymmetrical maxilla with deviation but complementary to each other, 6. Symmetrical mandible without deviation, and 7. Asymmetrical mandible with deviation, 8. Asymmetrical mandible with deviation but complementary to each other.The present method for three-dimensional evaluation made it possible to classify the state of asymmetry and/or deviation of the maxilla and the mandible in cases with diverted jaw. This VR method may be helpful in determining a more suitable treatment plan for jaw-deformity patients with deviation.

An electromyographic evaluation of the bilateral symmetry and nature of masticatory muscle activity in jaw deformity patients during normal daily activities.

This study was designed to investigate the nature of masticatory muscle activity and the balance in the bilateral symmetry of the masticatory muscle activity in jaw deformity patients. Fifteen patients (19.9 +/- 5.3 years) with lateral shift of the mandible caused by transverse craniofacial deformity and 15 controls (28.6 +/- 1.9 years) were used as the subjects in this study. Surface electromyographic (EMG) activities were recorded from the bilateral masseter and anterior temporal muscles during daytime (142 min, including mealtime) and sleep (142 min). The averaged rectified EMG values were normalized with reference to the EMG amplitude induced by a 98-N bite force. Bilateral symmetry of masseter and anterior temporal muscle activities was examined using an asymmetry index (AI) for both the controls and the patients. The normalized activities of the masseter and anterior temporal muscles during normal daily activities were lower in patients than in the controls. Asymmetry indices in patients were significantly greater during usual daytime activities and sleep for the anterior temporal muscle and significantly smaller during sleep for the masseter muscle as compared with the controls. The results show that masticatory muscle activity is lower in these jaw deformity patients in association with more prominent asymmetry of anterior temporal muscle activity than in the controls. It is suggested that these findings are highly relevant to occlusal interference and instability because of malocclusion and lateral mandibular deviation.

ＣＴ画像を用いた上顎Ｌｅ Ｆｏｒｔ Ｉ型骨切り術による上顎前方移動時の骨接触について

This study simulated the bone support after maxillary advancement by CT images and evaluated morphological characteristics of maxillary sinus in Le Fort I osteotomy sites. For forty-nine Japanese jaw deformity patients, CT images were taken before orthognathic surgery. In 3mm and 5mm maxillary advancement, the overlap of bone images was examined from the CT images 2mm above the anterior nasal spine of maxilla. The results were as follows: All cases had bony contact at the lateral piriform rim, the base of the zygomatic process of the maxilla and the medial wall of the sinus in 5mm maxillary advancement. Few cases had bony contact at the anterior wall in 3mm. Some cases had it at the posterior wall in 3mm or 5mm. The shape of the posterior wall of the maxillary sinus was subjectively grouped into the following three types: Straight type, S type or J type. In the S and J types, the percentage of bony contact of the posterior wall after maxillary advancement was higher than that in the Straight type.These findings suggest that the preoperative CT scan along the osteotomy line is clinically useful.

ＰＬＬＡ製スクリューを用いた下顎枝矢状分割術後の近・遠位骨片の安定性

The biodegradable poly-L-lactic acid (PLLA) screw is a newly developed surgical material for use in fixing bone segments in sagittal split ramus osteotomy (SSRO) of the mandible for jaw deformity patients. The purpose of this study was to examine the stability of dento-facial morphology of mandibular prognathism patients after SSRO using PLLA screws. Six patients who underwent SSRO with PLLA screws (3 males and 3 females; the PLLA group), and six patients who underwent SSRO with conventional titanium screws (2 males and 4 females; the titanium group), were compared using frontal and lateral cephalograms taken before, as well as at 0, 6, and 12 months after, the surgery. The cephalometric changes, which were evaluated using standard scores, revealed no significant difference between the two groups at any postsurgical stages. No complications, such as allergy, inflammation, and pain, were reported in either the PLLA or the titanium group. These results suggested that the PLLA screw might be a useful surgical material that can be chosen for bone fixation in SSRO of jaw deformity patients.