Biomedical subjects

Y R Chen

Publications and source records attributed to Y R Chen.

At least 55 records · Page 3Linked to original sources

PubMed1999

Electron spin resonance investigation of the cyanyl and azidyl radical formation by cytochrome c oxidase.

Cyanide (CN(-)) is a frequently used inhibitor of mitochondrial respiration due to its binding to the ferric heme a(3) of cytochrome c oxidase (CcO). As-isolated CcO oxidized cyanide to the cyanyl radical ((.)CN) that was detected, using the ESR spin-trapping technique, as the 5,5-dimethyl-1-pyrroline N-oxide (DMPO)/(.)CN radical adduct. The enzymatic conversion of cyanide to the cyanyl radical by CcO was time-dependent but not affected by azide (N(3)(-)). The small but variable amounts of compound P present in the as-isolated CcO accounted for this one-electron oxidation of cyanide to the cyanyl radical. In contrast, as-isolated CcO exhibited little ability to catalyze the oxidation of azide, presumably because of azide's lower affinity for the CcO. However, the DMPO/(.)N(3) radical adduct was readily detected when H(2)O(2) was included in the system. The results presented here indicate the need to re-evaluate oxidative stress in mitochondria "chemical hypoxia" induced by cyanide or azide to account for the presence of highly reactive free radicals.

Animals↗

PubMed1999

Lack of correlation in JNK activation and p53-dependent Fas expression induced by apoptotic stimuli.

Induction of Fas expression by DNA-damaging agents is dependent on the expression of functional p53, and has been suggested to play an important role in apoptosis induction. JNK (c-Jun N-terminal kinase), which is capable of phosphorylating p53, is also involved in apoptotic signaling induced by various apoptotic stimuli. Here, we report that although Fas induction is closely linked to the expression of wild type p53, it is not correlated with JNK activation induced by apoptotic stimuli. JNK activation does not necessarily lead to Fas expression, even in cells containing wild type p53. In addition, Fas expression can be induced without significant JNK activation. Furthermore, induction of Fas expression is not sufficient for apoptosis induction; however, it may sensitize cells to Fas-ligation induced apoptosis.

Antibodies↗

PubMed1999

An electron spin resonance spin-trapping investigation of the free radicals formed by the reaction of mitochondrial cytochrome c oxidase with H2O2.

The reaction of purified bovine mitochondrial cytochrome c oxidase (CcO) and hydrogen peroxide was studied using the ESR spin-trapping technique. A protein-centered radical adduct was trapped by 5, 5-dimethyl-1-pyrroline N-oxide and was assigned to a thiyl radical adduct based on its hyperfine coupling constants of aN = 14.7 G and abetaH = 15.7 G. The ESR spectra obtained using the nitroso spin traps 3,5-dibromo-4-nitrosobenzenesulfonic acid (DBNBS) and 2-methyl-2-nitrosopropane (MNP) indicated that both DBNBS/.CcO and MNP/.CcO radical adducts are immobilized nitroxides formed by the trapping of protein-derived radicals. Alkylation of the free thiols on the enzyme with N-ethylmaleimide (NEM) prevented 5, 5-dimethyl-1-pyrroline N-oxide adduct formation and changed the spectra of the MNP and DBNBS radical adducts. Nonspecific protease treatment of MNP-d9/.NEM-CcO converted its spectrum from that of an immobilized nitroxide to an isotropic three-line spectrum characteristic of rapid molecular motion. Super-hyperfine couplings were detected in this spectrum and assigned to the MNP/.tyrosyl adduct(s). The inhibition of either CcO or NEM-CcO with potassium cyanide prevented detectable MNP adduct formation, indicating heme involvement in the reaction. The results indicate that one or more cysteine residues are the preferred reductant of the presumed ferryl porphyrin cation radical residue intermediate. When the cysteine residues are blocked with NEM, one or more tyrosine residues become the preferred reductant, forming the tyrosyl radical.

Animals↗

PubMed1999

Identification of a catalytic aspartyl residue of D-ribulose 5-phosphate 3-epimerase by site-directed mutagenesis.

Guided by comparative sequence considerations, we have examined the possibility of a catalytic role of Asp186 of D-ribulose 5-phosphate epimerase by site-directed mutagenesis of the recombinant spinach enzyme. Accordingly, D186A, D186N, and D186E mutants of the epimerase were constructed, purified, and characterized; as judged by their electrophoretic mobilities the mutants are properly assembled into octamers like the wild-type enzyme. Based on the extent of internal quenching of Trp fluorescence, the conformational integrity of the wild-type enzyme is preserved in the mutants. The wild-type kcat of 7.1 x 10(3) s-1 is lowered to 3.3 x 10(-4) s-1 in D186A, 0.13 s-1 in D186N, and 1.1 s-1 in D186E; as gauged by D186A, altogether lacking a functional side chain at position 186, the beta-carboxyl of Asp186 facilitates catalysis by >10(7)-fold. Relative to the wild-type enzyme, the Km for D-ribulose 5-phosphate is essentially unaltered with D186N and D186E but increased 10-fold with D186A. Apart from their impairments in epimerase activity, the mutants are unable to catalyze exchange between solvent protons and the C3 proton of substrates. This deficiency and the differential alterations of kinetic parameters among the mutants are consistent with Asp186 serving as an electrophile to facilitate alpha-proton abstraction. This study is the first to identify a catalytic group of the epimerase.

Amino Acid Sequence↗

PubMed1999

Relationships of plasma tryptophan availability to course of illness and clinical features of alcoholism: a preliminary study.

RATIONALE: Serotonergic (5-HT) mechanisms may be involved in impulse control (including antisocial behavior) across psychiatric syndromes. Age of onset may differentiate alcoholics on psychopathological characteristics associated with impulse control, especially mood disturbance, hostility, and a broad range of antisocial behaviors. Thus, there may be a predictable relationship between markers of 5-HT function and age of onset-related characteristics. OBJECTIVE: We tested the hypothesis that there would be a predictable relationship between the ratio of plasma tryptophan to large neutral amino acids (i.e. TRYP/LNAA ratio), a marker of 5-HT function, age of onset and related psychopathological characteristics associated with impulse control. METHODS: Fifty-eight male and female DSM-IV diagnosed alcoholics attending an outpatient treatment center completing a comprehensive psychopathological assessment, and from whom blood samples were obtained. RESULTS: Plasma TRYP/LNAA ratio was positively correlated with symptoms of dysphoria, and negatively associated with harm avoidance on Cloninger's Temperament and Character Inventory. Low tryptophan availability was associated with antisocial-type personality characteristics. Interestingly, the few (nine) subjects who had both early onset alcoholism and antisocial personality disorder had a higher plasma tryptophan but similar TRYP/LNAA ratio to the others. CONCLUSIONS: These data suggest that a low plasma TRYP/LNAA ratio is associated with susceptibility to anxiety, antisocial-type personality characteristics, and an early age of onset for alcoholism. In contrast, a high plasma TRYP/LNAA ratio is associated with a later onset of alcoholism and dysphoria.

Age of Onset↗

PubMed1999

Temporomandibular joint reconstruction in children using costochondral grafts.

PURPOSE: The aim of this study was to evaluate the postoperative growth of the mandible after reconstruction of the condylar process using costochondral grafts in children. PATIENTS AND METHODS: Temporomandibular joint (TMJ) ankylosis was surgically treated and the joint reconstructed with a costochondral graft (CCG) in two boys and eight girls with a mean age of 7.4 years. Two children had bilateral ankylosis. Postoperative changes and craniofacial growth were monitored by lateral and posteroanterior (PA) cephalograms annually from 2 to 6 years (mean of 4 years). RESULTS: Postoperatively, in the eight children with unilateral TMJ reconstruction, the mandible (Co-Gn) grew an average of 14.7 mm in length on the affected side and 15.1 mm on the nonaffected side; ramus length (Co-Go) increased an average of 7.1 mm on the affected side and 7.3 mm on the nonaffected side. However, in five of the children the chin progressively deviated toward the nonaffected side after TMJ reconstruction. The CCGs tended to have a more vertically directed condylar growth pattern and a more laterally positioned condyle. In the two cases with bilateral TMJ reconstruction, the CCGs grew until there was a mandibular prognathism that required orthognathic surgery to set back the mandible. CONCLUSIONS: Using CCGs to reconstruct TMJ ankylosis in children provides a functional condyle with growth potential. However, there is a possibility of excessive growth of the graft, resulting in deviation of the chin and mandibular prognathism years later.

Ankylosis↗

PubMed1999

Structural studies of symmetric DNA undecamers containing non-symmetrical sheared (PuGAPu):(PyGAPy) motifs.

Interstrand purine-purine stacks originate from tandem sheared purine.purine pairing and represent one of the most important motifs in both DNA and RNA structures. Several RNA and DNA structures, solved recently in both solution and the solid state, contain these special motifs, which greatly increase the structural diversity of nucleic acid molecules. The direct evidence for the sheared purine-purine pairing at neutral pH in solution remains, however, elusive. In this manuscript, we have used high resolution NMR methods to study a series of symmetrical DNA duplexes containing two non-symmetrical 5'-(PuGAPu)/(PyGAPy)-3' motifs. Many strong- and medium-strength NOEs across the G.A base pair were detected in the H2O-NOESY spectra collected at a relatively low temperature (-5 degrees C). These NOEs, especially those from A-6NH2 to G-H1', G-H4', and G-2NH2, clearly define the proposed side-by-side sheared G.A pairing nature. Another interesting feature is the strong NOEs exhibited by the unpaired G-imino proton in the G.A pair to its own G-2NH2, which implies that G-2NH2 is involved in H-bonding with a base in the minor groove edge. The finding that non-symmetrical (PuGAPu):(PyGAPy) motif also form similarly stable structures loosens the requirement for a more restricted (PyGAPu)2 motif in forming the interstrand purine-purine stacks.

Base Pairing↗

PubMed1999

Intralesional photocoagulation of vascular anomalies of the tongue.

Vascular anomalies remain a challenge for patients and reconstructive surgeons. Recently, promising results have been reported using intralesional photocoagulation (ILP) to treat large, deep vascular lesions. We report our experience in treating 12 patients with vascular anomalies of the tongue (10 venous malformations and two haemangiomas) using intralesional photocoagulation. All patients were treated with a Nd:YAG (neodymium:yttrium-aluminium-garnet) (1064 nm) laser (Sharplan, Inc., NJ, USA) delivered with a 600 microns optical fibre. Laser power was set at 7 or 10 W, delivered with a pulse duration of 10 s. Laser energy was delivered to all areas of the vascular lesion. Heat, visible shrinkage and firmness of the lesion signalled the end-point of treatment. The mean follow-up period was 9.5 months (range 3-20 months). All patients demonstrated improvement as judged by a clinical assessment of the reduction in lesion size (mean reduction = 87%, range 60-100%). Three patients (25%) had complications attributed to photocoagulation. Energy delivered too superficially resulted in ulceration or scarring. These complications should be avoidable if this potential for harm is kept in mind.

Adult↗

PubMed1999

Palatoalveolar outcome at 18 months following simultaneous primary cleft lip repair and posterior palatoplasty.

It is frequently reported that early repair of the soft palate induces narrowing of the remaining palatal cleft and thus facilitates later hard palate closure. However, to the best of our knowledge, there have been no comparative studies to test this hypothesis. The purpose of this retrospective study was to evaluate the change of palatoalveolar morphology following primary lip repair and posterior palatoplasty. Dental plaster models of patients with complete unilateral cleft of lip and palate (UCLP) were used to measure the width of the cleft and palatal arch. Twenty-six patients received simple posterior palatoplasty (PP group) simultaneous with primary lip repair, and 20 patients did not (NPP group). The dental models included one preoperative cast at 2 months (T1) and two or three casts at 6 (T2), 12 (T3), and 18 (T4) months before final palate closure. The linear measurements performed were width of alveolar cleft (Ca); width of palatal cleft between the canines (Cc), molars (Cm), and tuberosities (Ct); the palatal arch distance between the canines (Dc); the widest distance between molars (Dm) and the tuberosities (Dt); and the palatal height between the canines (Hc) and tuberosities (Ht). The raw measurements and the calculated cleft-to-arch ratios of Cc/Dc, Cm/Dm, and Ct/Dt were compared between the two groups. The results showed gradual narrowing of the width of cleft from T1 to T4. Narrowing of alveolar cleft width (Ca) from T1 to T2 was dramatic. The palatal arch (Dc, Dm, Dt) showed no change to mild increase in width. The cleft-to-arch ratios decreased with time. The palatal height remained the same or slightly increased over time. There were no significant differences observed between the PP and NPP groups among these measurements except for the Ct and Ct/Dt at T4. In conclusion, after initial lip repair, there was a decrease of the width of cleft in patients with complete UCLP during the 18-month period, and simple posterior palatoplasty did not further narrow the cleft nor influence palatal arch development.

Chi-Square Distribution↗

PubMed1999

Airway obstruction in severe syndromic craniosynostosis.

Airway obstruction is frequent in patients with severe syndromic craniosynostosis, and must be treated for successful, complete care. The purpose of this study was to evaluate the incidence and the management of airway obstruction in patients with severe craniosynostosis. All patients with complex syndromic craniosynostosis at Chang Gung Craniofacial Center were evaluated retrospectively. Criteria for inclusion of patients were the presence of adequate follow-up and documentation. A total of 40 patients were included, of whom 13 had Apert's syndrome and 27 had Crouzon's disease. Clinical symptoms and signs related to airway obstruction and its treatment were evaluated carefully, and were verified further by telephone inquiry. The status of the airway was categorized into one of three groups: no obstruction; mild obstruction, for which positioning and medical treatment were needed; and severe obstruction, for which surgical intervention was needed. The results showed that 24 patients (60%) did not have airway obstruction, 11 patients (27.5%) had mild obstruction, and 5 patients (12.5%) had severe obstruction. There was no significant difference in the distribution of airway status between patients with Apert's syndrome and Crouzon's disease. Causes for the 5 patients with severe obstruction were midface hypoplasia, lower airway obstruction, tonsillar and adenoid hypertrophy, and choanal atresia. Tracheostomy was performed to control airway in 3 patients, and 1 patient died. Midface anterior distraction helped to decannulate 1 patient. In conclusion, airway obstruction was observed in 40% of patients with severe craniosynostotic syndromes. Most of them could be managed successfully with conservative or medical treatment, and surgical intervention should be considered on the basis of each patient's individual condition.

Acrocephalosyndactylia↗

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

Endoscopically assisted mandibular subcondylar fracture repair.

The endoscope has been widely used in aesthetic surgery in recent years, but rarely has it been used in cases of facial trauma. From July of 1996 to December of 1996, the endoscope was used successfully to assist in the repair of mandibular subcondylar fractures in eight patients (five men and three women). Their ages ranged from 15 to 60 years with an average age of 31 years. Six of the patients had other associated mandibular fractures including angular, parasymphyseal, and contralateral subcondylar fractures. A 4.0-mm, 30-degree telescope was introduced to visualize the fracture site by means of an intraoral incision over the ascending ramus. A miniplate was used to stabilize the fracture site with the help of a percutaneous trocar. Intermaxillary fixation was applied for 3 to 6 days. Functionally, all patients returned to normal range of motion within 8 weeks. A slight deviation to the trauma site was noted on maximal opening in three patients, but this condition returned to normal 3 months after surgery. There was no facial palsy or lip numbness. The benefits of the endoscopic approach include not only the provision of better visualization and precise anatomic alignment of bony segments but also the avoidance of large facial scars and facial nerve injuries.

Adolescent↗

PubMed1999

Endoscopically assisted reconstruction of orbital medial wall fractures.

Traditional surgical approaches to orbital medial wall fractures are either direct extraocular skin incisions or indirect bicoronal flap. However, these methods can leave remarkable orbital scars or scalp alopecia with the possible associated complications. A minimally invasive endoscopic technique with the assistance of a 2.7-mm, 30-degree telescope through a medial transconjunctival incision has been successfully used to reconstruct the orbital medial wall fractures. This technique was applied to four patients who had orbital medial wall fractures. Three patients also had concomitant orbital floor fractures. The other had associated superior orbital fissure syndrome. All patients were presented with limited eye movement, positive forced duction test, horizontal diplopia, and enophthalmos (3 mm to 6 mm) preoperatively. The entrapped periorbital tissues in the ethmoid sinus were completely reduced endoscopically. The bone defect of orbital medial wall was reconstructed with autogenous rib bone grafts under endoscopic control. The patients were followed up for 8 to 16 months with an average of 11 months. Three patients recovered completely without any residual eye symptoms after intervention. Clinically significant residual enophthalmos of 3 mm occurred in the patient with the superior orbital fissure syndrome. His eye movement limitation caused by entrapment of medial rectus muscle was relieved postoperatively. There was no donor-site morbidity or any complications related to the endoscopically assisted procedure. Endoscopically assisted medial transconjunctival approach to the orbital medial wall fractures is an excellent adjunct for the exposure and complete reduction of herniated periorbital tissue and bony reconstruction of the medial orbital wall.

Adult↗

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

Three-dimensional computed tomographic analysis of the primary nasal deformity in 3-month-old infants with complete unilateral cleft lip and palate.

The purpose of this study was to analyze the geometry of the primary cleft lip nasal deformity using three-dimensional computerized tomography in a group of 3-month-old infants with complete unilateral cleft lip and palate before surgical intervention. Coordinates and axes were reconfigured after the three-dimensional image was oriented into neutral position (Frankfurt horizontal, true anteroposterior, and vertical midline). Display and measurement of skin surface and osseous tissues were achieved by adjusting the computed tomographic thresholds. S-N, N-ANS, S-N-O, and S-N-ANS were measured from true lateral views. Biorbital (LO-LO), interorbital (MO-MO), intercanthal (en-en), and nasal (al-al) widths were measured from the anteroposterior view. The bony alveolar cleft width was measured from the inferior view. The study group was divided into two groups on the basis of skeletal alveolar cleft width: six patients with clefts narrower than 10 mm and six patients with clefts wider than 10 mm. Only the S-N-ANS angle differed between the two groups, i.e., it was greater in the group with the wider clefts (p < 0.05). Coordinates of six landmarks at the base of the nose [sellion (se), subnasale (sn), cleft-side and noncleft-side subalare (sbal-cl and sbal-ncl), and the most posterior point on the lateral piriform margins (PPA-CL and PPA-NCL)] were obtained for analysis of the nasal deformity. On average, the subnasale point was anterior to sellion and deviated to the noncleft side; the cleft-side sbal point was more medial, posterior, and inferior than the noncleft-side sbal point; and the PPA point on the cleft-side piriform margin was more lateral, posterior, and inferior than the PPA point on the noncleft side. These discrepancies were not universally observed. However, in all patients, four findings were observed without exception (p < 0.01): (1) subnasale (sn) was deviated to the noncleft side (mean distance from midline, 5.0 mm; range, 2 to 9.5 mm), (2) the cleft-side alar base (sbal-cl) was more posterior than the noncleft-side alar base (sbal-ncl) (mean difference, 3.6 mm; range, 1 to 5.5 mm), (3) the noncleft-side alar base (sbal-ncl) was further from the midline than the cleft-side alar base (sbal-cl) (mean difference in lateral distances of sbal-ncl and sbal-cl from the midline, 2.8 mm; range, 0.5 to 7 mm), and (4) the cleft-side piriform margin (PPA-CL) was more posterior than the noncleft side piriform margin (PPA-NCL) (mean difference, 2.1 mm; range, 0.5 to 4 mm). In conclusion, the nasal deformity in unilateral cleft lip and palate that has not been operated on is characterized by these four features and increased S-N-ANS angle with increased alveolar cleft width.

Cephalometry↗

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↗