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Biomedical subjects

V K Yeow

Publications and source records attributed to V K Yeow.

14 recordsLinked to original sources
PubMed1999

Orthognathic surgery in craniomaxillofacial fibrous dysplasia.

In craniomaxillofacial fibrous dysplasia, jaw involvement often causes facial asymmetry, an occlusal cant, and loss of teeth. Although conservative management of fibrous dysplasia affecting the jaws is widely practiced, orthognathic surgery is indicated in such cases to restore occlusion and correct dentofacial deformity brought on by the disease process. Since 1981, the Craniofacial Center at Chang Gung Memorial Hospital in Taiwan has treated a total of 84 patients with craniomaxillofacial fibrous dysplasia. Of these, 55 (65%) had fibrous dysplasia affecting the jaws (Zone 4). Between 1988 and 1997, orthognathic surgery was performed on 1 male and 4 female patients with fibrous dysplasia involving the teeth-bearing jaws. One patient had localized fibrous dysplasia that involved the mandible. The other 4 patients had polyostotic craniofacial involvement of Zones 1, 2, or 3 and 4A. The patient with isolated mandibular involvement and 2 patients with maxillary fibrous dysplasia had single-jaw surgery. The other 2 patients with maxillary involvement required simultaneous two-jaw surgery to correct the dentofacial deformities resulting from the disease process. Follow-up ranged from 12 months to 9 years. All the patients had stable occlusion, good facial aesthetics, and no further recurrence after surgery. The long-term stability of the achieved occlusion and facial appearance confirms that adequate healing in fibrodysplastic bone is to be expected using the standard fixation.

Adult↗
PubMed1999

Combining single- and double-tooth osteotomies with traditional orthognathic surgery.

Combining large-segment orthognathic surgery and unitooth or small-segment surgery is an effective approach to deal with a wide range of dentofacial deformities that have minor to severe occlusal problems. The indications for combining single- or double-tooth osteotomies with traditional orthognathic surgery were patients with dentofacial deformities and malocclusion requiring stable correction within a short overall treatment period. From 1991 to 1998, a total of 36 patients underwent combination single- or double-tooth-segment osteotomy with traditional orthognathic procedures performed at Chang Gung Memorial Hospital. The indications for surgery were maxillary protrusion (N = 5), bimaxillary protrusion (N = 19), mandibular prognathism with maxillary protrusion (N = 11), and noncleft maxillary retrusion (N = 1). The types of osteotomies performed were the Le Fort I, the anterior segmental osteotomies of the maxilla or the mandible, the palatal split, and the posterior segment in combination with single-tooth or double-tooth segments. Follow-up ranged from 12 months to 6 years and showed stability in the movements with no complications. There was no loss of any "osteotomized" segment. The average overall treatment time was approximately 18 months--5 months preoperative and 13 months postoperative orthodontic treatment. This was at least 6 months shorter in duration compared with traditional orthognathic surgery. Combining traditional orthognathic surgery with single- or double-tooth segments allows us to treat complex dentofacial deformities in the vertical, transverse, and sagittal dimensions with differential repositioning of all segments, either major or minor, simultaneously. The authors' experience with 36 consecutive patients evidence good results and demonstrate the procedure to be safe with minimal complications.

Adolescent↗
PubMed1999

Cleft lip scar camouflage using dermal micrografts.

The use of dermal micrografts to camouflage cleft lip scars is a simple and effective method. We have used dermal micrografts, some hairbearing, to camouflage hypopigmented scars in 10 patients. This method improves the color of the scar, corrects wound distortion and direction to a certain degree, and enables the resultant scar to blend into the adjacent tissue more naturally. Unlike with other methods of scar revision, additional tissue is not sacrificed and new incision lines are not created.

Adolescent↗
PubMed1999

The use of nasal splints in the primary management of unilateral cleft nasal deformity.

Primary surgical correction of the cleft lip nasal deformity is routinely performed at the Craniofacial Center at Chang Gung Memorial Hospital. Over time, however, there is a tendency for the lower lateral cartilage to retain its memory and, subsequently, recreate the preoperative nasal deformity. Therefore, it is current practice to use a nostril retainer for a period of at least 6 months to maintain the corrected position of the nose. The aim of this study was to qualitatively assess the benefit of postoperative nasal splinting in the primary management of unilateral cleft nasal deformity. Data from two groups of 30 patients with complete unilateral cleft lips each were retrospectively collected and analyzed. The first group served as a control (no nasal splints), and the second group used the nasal retainer compliantly for at least 6 months postoperatively. All patients had their primary lip repair at 3 months of age. A photographic evaluation of the results when the patients were between 5 and 8 years of age was conducted. The parameters used to assess the nasal outcome were nostril symmetry, alar cartilage slump, alar base level, and columella tilt. The first scores were based on residual nasal deformity, and the second set were based on overall appearance. It was found that the mean scores of residual nasal deformity for all four parameters in patients who used the nasal stent were statistically better than the scores of patients who did not (p values ranged from 0.0001 to 0.005). The overall appearance scores for the four parameters in the patients who used the nasal stent after surgery were also statistically better than the scores for those who did not (p values ranged from 0.0001 to 0.01). The results show that postoperative nasal splinting in the primary management of the unilateral cleft nasal deformity serves to preserve and maintain the corrected position of the nose after primary lip and nasal correction, resulting in a significantly improved aesthetic result. Therefore, it is recommended that all patients undergoing primary correction of complete unilateral cleft deformity use the nasal retainer postoperatively for a period of at least 6 months.

Cleft Lip↗
PubMed1999

Multiple-segment osteotomy in maxillofacial surgery.

Multiple-segment osteotomy is defined as an osteotomy that divides the tooth-bearing arch of the maxilla or mandible into three or more segments. Combining large-segment orthognathic surgery and unitooth or small-segment surgery is an effective approach for dealing with a wide range of dentofacial deformities with occlusal problems. The indications for a multiple-segment osteotomy included dentofacial deformities and malocclusions requiring stable correction within a short overall treatment period. From 1991 to 1997, a total of 85 patients had multiple-segment osteotomy orthognathic procedures performed at Chang Gung Memorial Hospital. The indications for surgery were maxillary protrusion/deformity (31 patients), mandibular prognathism (51 patients), and noncleft maxillary retrusion (three patients). The types of osteotomies performed were Le Fort I, anterior segmental osteotomies of the maxilla or the mandible, palatal split, posterior segment, and unitooth or double-tooth segments. Follow-up ranged from 6 months to 7 years; stability was seen in movements, with only three complications (one partial gingival loss and two inferior mental paresthesias). No osteotomized segments were lost. The average overall treatment time was approximately 15 months, including 3 to 6 months of preoperative and 9 to 12 months of postoperative orthodontic treatment. This is at least 6 months shorter than traditional orthognathic surgery. Experience with 85 consecutive patients has shown that the results are good and the procedure is safe, with minimal complications.

Adolescent↗
PubMed1999

Augmentation of the nasal floor with Surgicel in primary lip repair: a prospective study showing no efficacy.

The symmetry of the alar base and the nasal floor is very important in achieving a satisfactory result in primary lip and nasal reconstruction during cleft lip repair. The skeletal base of the nasal pyramid is usually hypoplastic even in incomplete clefts. A periosteal pocket filled with Surgicel can facilitate blood clot formation and can theoretically stimulate bone formation, thereby improving the asymmetry of the bone base. To test this hypothesis, a prospective study was performed in 64 primary lip repairs by comparing the effect of subperiosteal nasal floor augmentation with Surgicel. From February 1989 to June 1993, 64 patients with incomplete cleft lips (excluding occult cleft lip and complete clefts with Simonart's band) were operated by the same surgeon. The patients were divided randomly into two groups. One group had subperiosteal nasal floor augmentation with Surgicel and the other group did not. The lip repair was a rotation-advancement cheiloplasty with primary closed rhinoplasty of the tip and ala. In the first group, a subperiosteal pocket was created under the cleft alar base and the nasal floor. The pocket was filled with Surgicel up the point where the level of the alar base and the nasal floor was symmetrical with the noncleft side. The control group underwent a similar procedure, less the creation of the subperiosteal pocket and the use of Surgicel. All patients were followed for at least 3 years and their photographs were used to compare and analyze the results of their nasal correction. Critical attention was paid to the symmetry of their nasal floor and alar base. The results were evaluated by at least two plastic surgeons for consistency. The data indicate that the control group showed a higher number of subjects with asymmetry (10 of 32) compared with the study group (8 of 32). However, there was no statistical significance to the findings. Two patients in the study group who received Surgicel developed hypertrophic lip scars. This study, although unable to determine statistically the contributory affect of Surgicel in primary nasal reconstruction, does show a possible benefit from the use of osteogenic materials in the primary management of the deficient nasal floor. Hypertrophic scars developed by 2 patients in the study group may point to a possible soft-tissue reaction to the use of Surgicel in primary lip and nasal repair.

Cellulose, Oxidized↗
PubMed1999

A review of mandibular fractures in a craniomaxillofacial trauma centre.

This report is a retrospective review of 74 cases of mandibular fractures managed in a craniomaxillofacial trauma centre between January 1994 and May 1998. Demographic data revealed that 85% of the patient population were male, with a mean age of 27.5 years. The commonest causes of injury were motor vehicle accidents (48.6%), followed by assault (16.2%) and accidental falls (17.6%). In 25 patients (33.8%) the fractures were single. Of these, fractures of the condylar region were the most common (8 patients). The remaining patients sustained fractures in two or more anatomic sites. There were other associated facial fractures in 45.9% of patients. Trauma to other systems was present in 37.8%, with orthopaedic and neurosurgical injuries being the most common. Surgical management in the form of open reduction and internal fixation was carried out in 61 patients (82.4%). Maxillo-mandibular fixation was used as an adjunct to maintain occlusion and bony reduction in unstable and comminuted fractures (15 patients, 20.3%), and as the primary mode of treatment in patients with stable, undisplaced fractures, particularly condylar fractures, in which the pretraumatic occlusal relationship was not disrupted (9 patients, 12.2%). A successful outcome was defined as a stable and healed fracture, with restoration of functional occlusion, facial symmetry and facial aesthetics. Complications observed included temporomandibular joint dysfunction (10.8%), malocclusion (9.5%), infection (8.1%), implant exposure (5.4%), and non-union or delayed union (4.1%).

Accidents, Traffic↗
PubMed1999

Epidemiology of cleft lip and palate in Singapore--a 10-year hospital-based study.

During the study period from January 1985 to December 1994, there were 1105 new cleft cases seen in the Department of Plastic Surgery, Singapore General Hospital. These included newborn as well as unoperated children and adult cases. During the same period, the total number of recorded births in Singapore was 474,542. Out of the 1105 new cleft cases seen, 984 were Singaporeans. The incidence of this hospital-based study of cleft population in Singapore was 2.07 per 1000 livebirths. Chinese had the highest incidence of 1.64 per 1000 as compared to Malay, Indian and other races. The most common type of cleft deformity was complete cleft lip and palate. The left side was found to be more affected than the right side in all types of cleft deformity. There was no significant difference in sex distribution; the male to female ratio was 1.1:1. However, females had a higher incidence of cleft palate than males. Associated congenital deformities occurred in 1.5% of the total cleft population.

Acrocephalosyndactylia↗
PubMed1999

The role of multiple segment osteotomies in orthognathic surgery.

Multiple segment orthognathic (MSO) surgery is an effective approach to deal with a wide range of dento-facial deformities that have occlusal problems. The indications for MSO surgery were patients with dentofacial deformities and malocclusion requiring stable correction within a short overall treatment period. From 1991 to 1998, 107 patients had MSO orthognathic procedures done at Chang Gung Memorial Hospital for maxillary protrusion/deformity (34 cases), maxillary protrusion and mandibular prognathism (69 cases), and non-cleft maxillary retrusion (4 cases). Follow up period ranged from 6 months to 7 years and results showed stability in movements with only 3 complications. The average overall treatment time was approximately 15 months. Our experience with 107 consecutive patients have shown the results of MSO surgery to be good and the procedure safe with no tooth or segment loss.

Adolescent↗
PubMed1999

Midface distraction osteogenesis in cleft patients: a case report.

We present a case of midface distraction in a bilateral cleft lip and palate patient. The patient was a 10-year-old who underwent a high LeFort I osteotomy followed by placement of the Rigid External Distraction halo. Distraction was commenced on the fifth postoperative day at a rate of 1 to 1.5 mm per day until a total of 17 mm of maxillary advancement had been achieved. There were no complications and follow up was at 9 months post distraction. Results show that the patient had improved facial aesthetics and dental occlusion which was overcorrected to a Class III relationship. Velopharyngeal function was unaffected. Distraction osteogenesis of the midfacial skeleton in cleft patients offers the possibility to remodel not only the underlying bony skeleton but also all the soft tissues of the face and palate.

Child↗
PubMed1998

The "Taiwanese giant": hormonal and genetic influences in fibrous dysplasia.

A 14-year-old boy has been followed for 4 years with a rapidly growing, recurrent area of fibrous dysplasia of the left maxilla and zygoma following resection and bone grafting. Standing 190 cm tall, he was found to have elevated serum growth hormone levels and a pituitary adenoma. His case appears to represent a postzygotic gene mutation of McCune-Albright syndrome. It is possible that the elevated growth hormone levels are in part responsible for the rapid progression of the tumor.

Adolescent↗
PubMed1998

Transzygomatic coronoidectomy through an extended coronal incision for treatment of trismus due to an osteochondroma of the coronoid process of the mandible.

Osteochondroma is the most common benign tumor of the skeletal system. In the craniofacial skeleton, however, osteochondroma is uncommon. Even more rare is osteochondroma of the coronoid process. A review of the literature reveals only 31 reported cases of osteochondroma of the coronoid process of the mandible. The preponderance of patients were young men (67.7%) and most presented with a facial deformity. As a benign tumor, the problems with surgical treatment have dealt with the inaccessibility of the lesion and hence the surgical approach of choice. The previous surgical approaches have either been intraoral, external, or a combination of both. We present a transzygomatic approach via a coronal incision that gives excellent access and a good cosmetic result, and protects the facial nerve from damage.

Bone Plates↗
PubMed1998

Effect of cranial suture autotransplantation from metopic to coronal suture.

The aim of this study was to determine the outcome of autotransplanting part of the metopic suture to a defect in the coronal suture in a pig model and to explore further the concept of functioning and nonfunctioning recipient sites. The authors harvested 15-mm x 10-mm bone grafts, incorporating a part of the metopic suture, in 10 Yorkshire pigs under general anesthesia. The authors immediately autotransplanted the grafts to a surgically created defect along the line of the coronal suture. Both donor and graft were either covered with pericranium or left bare. Radiopaque titanium markers were inserted to assess growth 1) of the transplanted suture; 2) across both coronal sutures; and 3) across the metopic suture. Serial radiographs were taken immediately after surgery and at 3-week intervals. The pigs were then killed at 21 weeks. The cranium was harvested, and blocks of donor site and graft were taken, incorporating the embedded titanium markers. Histologic analysis confirmed graft take in all pigs. All grafts continued to function as active cranial sutures with no growth disturbance compared with the contralateral coronal suture (P = 0.953). There was also regeneration of the donor defect, as confirmed by histologic analysis, with no growth disturbance across the metopic suture (P = 0.972). Pericranium did not alter graft take or subsequent growth (P = 0.964). However, pericranium resulted in a much smaller defect (P = 0.045). These results show that after autotransplanting a cranial suture to replace another cranial suture, the graft continues to grow and function as a cranial suture to meet the functional demands of the new recipient site. Pericranium has a significant effect on calvarial regeneration but does not affect cranial suture autotransplantation.

Animals↗