PubMed Health⌕ Search

Biomedical subjects

Lim K Cheung

Publications and source records attributed to Lim K Cheung.

13 recordsLinked to original sources
PubMed2007

Psychological profile of Chinese with cleft lip and palate deformities.

OBJECTIVE: To assess the psychological well-being of patients with cleft lip and palate (CLP). PATIENTS/SETTING: Ninety-four Chinese CLP subjects between 10 and 40 years of age were recruited from the Discipline of Oral and Maxillofacial Surgery, The University of Hong Kong, between June and December 2003. They were divided into two groups for comparison: adolescents (10-16 years old) and adults (17- 40 years old). A control group of 116 healthy non-CLP patients was also recruited during the same period. INTERVENTIONS: All CLP and non-CLP patients were asked to complete a set of four questionnaires to assess their psychological status. The questionnaires included the Social Avoidance and Distress Scale, the Satisfaction with Life Scale, the Culture-Free Self-Esteem Inventory, and the Chinese Miller Behavioral Style Scale. RESULTS: Chinese CLP patients exhibited levels of subjective well-being and social anxiety that were similar to the published levels of a group of British CLP patients. They also had significantly lower general and social self-esteem but higher parental self-esteem than the non-CLP control group. CONCLUSION: CLP patients were generally satisfied with life and did not exhibit more social anxiety than the non-CLP control group. They also had a good relationship with their parents. Gender and educational level had no influence on their psychological profile. However, these CLP patients had lower self-esteem than non-CLP patients.

Achievement↗
PubMed2006

Expression of tissue inhibitor of metalloproteinase during early stages of bone graft healing.

The aim of this study was to investigate the temporal expression of TIMP-1 within endochondral and intramembranous bone grafts during the early stages of healing in thirty six adult New Zealand white rabbits. Total RNA was isolated from bone grafts extracted on days 0-11 and day 14 post-grafting, for RT-PCR analysis. In situ hybridization was carried out on days 1-9 and day 14. Results showed TIMP-1 expression coincides with osteogenesis, which indicates a role for TIMP in preserving the newly formed bone during the initial stages of graft healing. Bone grafts play an important role in influencing the healing process mediated by the host tissues. The temporal expression of TIMP-1 differs in endochondral and intramembranous bone grafts. The earlier expression of TIMP-1 by endochondral bone grafts, could be the reason for the delayed vascularization while the expression of TIMP-1 by the intramembranous bone grafts, at a later stage could allow for earlier vascularization.

Animals↗
PubMed2005

Evaluation of recombinant human bone morphogenetic protein-2 in mandibular distraction osteogenesis in rabbits: Effect of dosage and number of doses on formation of bone.

We evaluated the dose- and time-dependent response of recombinant human bone morphogenetic protein-2 (rhBMP-2) to the formation of bone in mandibular distraction osteogenesis. Twenty-one adult white New Zealand rabbits (3.0-3.8 kg) were used to establish the mandibular distraction model, 18 of which completed the experiment. Eight rabbits were given rhBMP-2 360 microg and eight 1080 microg; two were given no rhBMP-2. The fluids were injected into the regenerating bone at three different time sequences (days 5, 8, and 11 of active distraction; days 5 and 11 of active distraction; and day 11 of active distraction alone). After four weeks of consolidation, the specimens were harvested and examined radiographically by micro-computed tomography (micro-CT), and histologically. The formation and remodelling of bone in distraction osteogenesis was significantly increased by the addition of rhBMP-2, and the increase was dose-dependent. There was no significant difference between different dosage regimens. A single injection of rhBMP-2 at the end of the distraction phase was as effective as multiple injections.

Animals↗
PubMed2004

Healing of maxillary alveolus in transport distraction osteogenesis for partial maxillectomy.

PURPOSE: This study aims to evaluate histologic healing of the new bone and soft tissue in the distraction gap of maxillary alveolus after transport distraction at different consolidation intervals. MATERIALS AND METHODS: In a monkey model, dentoalveolar segment was distracted backward to a surgical defect in the posterior maxilla with an internal distractor at a rate of 1 mm/day for 2 weeks. The distracted dentoalveolar processes were harvested at 1, 2, and 3 months of consolidation after the completion of distraction. Histologic examination included the new bone, gingiva of the distraction gap, and teeth carrying the transport segments. Tartrate-resistant acid phosphatase was used to assess the presence of osteoclasts in the new bone. The collagen type and expression of bone morphogenetic proteins (BMPs) in the new bone were assessed by immunohistochemistry. RESULTS: The histology confirmed new bone bridging the distraction gap at 1 month of consolidation. Woven bone was progressively replaced by mature lamellar bone at the second and third months. The gingiva covering the distraction gap was of normal appearance. There were no pathologic pulpal changes noted in the transport segment. Tartrate-resistant acid phosphatase-positive osteoclasts were minimal in the new bone. The mode of ossification was confirmed as intramembranous, and the fibrous stroma consisted mainly of collagen type I. At 1 month of consolidation, the BMPs were expressed profusely in the fibrous matrix and also inside the fibroblasts and osteoblasts. At 2 and 3 months of consolidation, the BMP expression intensity was reduced significantly in the fibrous stroma. CONCLUSIONS: The study confirmed that the bone regenerate in maxillary transport distraction was formed by intramembranous ossification and teeth in the transport segment remain viable after maxillary transport distraction osteogenesis.

Alveolar Process↗
PubMed2004

[Experimental study of the fungiform papilla and taste bud regeneration following microsurgical repair of lingual nerve in rat].

PURPOSE: To investigate the changes of taste buds following injury to lingual nerve and the regeneration of the fungiform papillae and taste buds following microsurgical epineurial anastomosis of transecting injured lingual nerves in rats. METHODS: We observed the numbers and shapes of the fungiform papillae and taste buds with stereomicroscope, light microscope, and scanning electron microscope at 20 and 100 days after the clamp injury to lingual nerve, or the transecting injury to lingual nerve with/without immediate microsurgical epineurial anastomosis of the injured lingual nerve in rats. RESULTS: The fungiform papillae and taste buds degenerated, atrophied and their numbers diminished obviously at 20 days following either the clamp injury or transecting injury to the lingual nerve. The fungiform papillae and taste buds didn't regenerate spontaneously at 100 days following transection of the lingual nerve without microsurgery. The degenerated fungiform papillae and taste buds regenerated and recovered completely at 100 days following both clamp injury to the lingual nerve and transection of the lingual nerve with immediate microsurgical epineurial anastomosis. CONCLUSION: The degenerated fungiform papillae and taste buds have good ability to regenerate spontaneously following clamp injury to the lingual nerve; the degenerated fungiform papillae and taste buds can regenerate completely with immediate microsurgical epineurial anastomosis of the transected lingual nerve. The quantity and morphology of fungiform papillae and taste buds can be used as objective indicators in the function rehabilitation of injured lingual nerve.

Animals↗
PubMed2004

Distraction or osteotomy for the correction of maxillary cleft deformities: which is better?

The application of distraction osteogenesis in the maxillofacial region is gaining popularity. However, it remains controversial whether distraction osteogenesis can produce better outcomes than the conventional orthognathic surgery particularly in cleft lip and palate (CLP) patients. This paper presents the two treatment methods--conventional orthognathic surgery and distraction osteogenesis in the management of maxillary hypoplasia in CLP patients. One clinical case was selected for illustration on each method. The discussion is based on the current literature focusing on the differences in indications, surgical techniques, morbidities, relapse, speech and velopharyngeal changes.

Adolescent↗
PubMed2003

Dental implants in reconstructed jaws: implant longevity and peri-implant tissue outcomes.

PURPOSE: The study aimed to evaluate the clinical status and survival of dental implants inserted in reconstructed jaws, with particular reference to the peri-implant tissues. MATERIALS AND METHODS: We conducted a clinical follow-up study based on 29 rehabilitated patients after oral tumor surgery, who received autogenous bone grafts from the ilium and endosseous implants (14 maxillary and 15 mandibular cases; 140 implants) for functional jaw reconstruction between 1988 and 1999. Clinical records of the patients were reviewed retrospectively. Clinical parameters of plaque index, probing pocket depth, and bleeding on probing were assessed around the implants and control teeth at 4 locations (mesiobuccal, distobuccal, mesiolingual, and distolingual). Implant mobility was assessed clinically and objectively using a Periotest (Gulden; Siemens, Bensheim, Germany) equipment for those implants supporting removable prostheses. Radiographically, the proportion of implant length remained osseointegrated was measured. RESULTS: With a mean follow-up time of 50 months, 90.7% of the 140 implants placed were functional in supporting dental prostheses; 4.3% of implants failed in osseointegration and the remaining 5.0% implants were osseointegrated but nonfunctional. A total of 493 sites of 127 functional implants and 392 sites of 98 control teeth were assessed. No significant difference was found between the implants and control teeth parameters, except on the probing pocket depth. The mean peri-implant probing depth was 3.5 mm, and 52.7% of the measured sites were 3 mm or less. More than one third of the implants (35.9%) presented with increased probing depth (> or =4 mm), and this was significantly higher than in the control teeth (P <.001, chi(2) test). Bleeding on probing was found in 19.3% of the measured peri-implant sites, corresponding to 42.2% of the dental implants. Of the implants, 28.9% were completely free from plaque and 9.4% show visible plaque accumulation. Mobility assessment was feasible on 32 implants and no mobility was detected. Radiographically, the mean implant length remained in bone was 81.1%, with 82.6% in the maxilla and 79.4% in the mandible. Implant survival rate calculated using the Kaplan-Meier method was 86.9% for 5 years. Based on the defined criteria, the success rate of implants placed in reconstructed jaws in this study was 90.7%. CONCLUSION: Endosseous implants can be successfully placed in reconstructed jaws for oral rehabilitation with maintenance of reasonable health status of the peri-implant tissues in the long-term.

Adolescent↗
PubMed2003

Stability consideration for internal maxillary distractors.

PURPOSE: Stability in distractor design ensures distraction osteogenesis healing with good bone regenerate formation. The aim of this study was to compare the holding strengths of different fixation systems for maxillary distractor design on bone pieces of different thicknesses. MATERIAL AND METHODS: Cross-sectional images of 10 dry skulls were obtained by computer tomography and the bone thickness of the maxillae were measured according to five individual anatomical regions (paranasal, infra-orbital, posterior sinus wall, zygomatic and alveolar regions). According to the measurements, the screws of 1.5 and 2mm in diameter and the three-screw mini-plates in triangular and straight configurations were evaluated for holding strength by pull-out tests on fresh animal bone pieces of defined thickness. RESULTS: The paranasal and zygomatic regions of the human skulls had the thickest cortical bone (4mm) followed by the alveolar region (2mm). In the bones of 2 and 4mm thickness, the 2mm screws were confirmed stronger than the 1.5mm ones in pull-out tests. However, the pull-out behaviour of screws of different diameters in 1mm thick bones and the mini-plates in two different configurations showed no significant differences. CONCLUSION: This study confirms that the paranasal and zygomatic bones are the thickest for fixation of internal maxillary distractors. Fixation screws of 2mm diameter in either triangular or straight miniplates can produce good stabilization for distractors.

Analysis of Variance↗
PubMed2003

Radiologic characterization of new bone generated from distraction after maxillary bone transport.

OBJECTIVE: The purpose of this study was to characterize the radiologic features of the new bone generated from distraction following maxillary bone transport. STUDY DESIGN: Maxillary dentoalveolar segments were transported by distraction to close posterior maxillectomy defects in 9 rhesus monkeys. The distracted dentoalveoli were harvested at 1, 2, 3, and 6 months after the completion of the distraction. The specimens were evaluated by plain radiography and microcomputerized tomography scanning, which included 2- and 3-dimensional quantitative analyses of bone regeneration volume and microstructural indices. RESULTS: Plain radiographs showed that radiolucency in the distraction regenerate reduced with time. Microcomputerized scanning found that bone formation and trabecular thickness increased in the new bone with longer consolidation. The high orientation and connectivity of the trabeculae were reduced at longer consolidation intervals. Within the whole distraction gap, bone volume was found to be site-specific. CONCLUSION: Morphologic analysis in the high resolution offered by microcomputerized tomography shows that active bone mineralization and remodeling occur in the new bone within 3 months after distraction in maxillary dentoalveolus.

Alveolar Process↗
PubMed2002

The long-term clinical morbidity of mandibular step osteotomy.

The objectives of this retrospective study were to assess the clinical applications of mandibular step osteotomy (MSO) and to evaluate its long-term clinical morbidities. A total of 152 patients with MSO performed between 1990 and 1999 were assessed. Forty-two patients were successfully recalled through questionnaires and clinical parameters for clinical evaluation, which included (1) tooth sensibility; (2) periodontal status; (3) neurosensory deficit in terms of light-touch threshold, 2-point discrimination, and pain threshold; and (4) temporomandibular joint function. The patients were finally asked about their overall satisfaction with the surgical treatment. The result revealed that MSO was commonly indicated for the correction of mandibular hyperplasia. Clinical assessments showed that 2.75% of the teeth assessed had negative pulpal response, 3.9% showed mildly increased probing depth, and another 3.9% showed gingival recession. Neurosensory assessment revealed that 31% of the operating sites had an increased light-touch threshold, 4.8% had heightened 2-point discrimination, and 9% had an elevated pain threshold. Also, 9.7% of the patients showed reduced mouth opening and 17% had mild tenderness of masticatory muscles. Of all the patients assessed, 12% were not satisfied with the orthognathic treatment. The reasons included relapse, residual asymmetry, and persistent paresthesia.

Adolescent↗
PubMedDate not supplied

Dental implants in reconstructed jaws: patients' evaluation of functional and quality-of-life outcomes.

PURPOSE: To evaluate the quality-of-life aspect of treatment outcome following functional jaw reconstruction and dental implants in the maxilla or mandible. MATERIALS AND METHODS: This cross-sectional study used a questionnaire interview of 28 rehabilitated patients who received autogenous bone grafts from the ilium and endosseous implants (14 maxillary and 14 mandibular cases; 134 implants) for functional jaw reconstruction between 1988 and 1999. A questionnaire was developed to assess the quality-of-life outcome for those patients who had finished their rehabilitation at least 6 months prior to the interview. Responses to the questions were recorded by means of visual analog scales. RESULTS: In general, patients gave positive comments on the restoration of their orofacial appearance and function (mastication and speech). The majority (85.7%) found no problem in various daily social activities, including dining in public. DISCUSSION: The overall level of satisfaction with the treatment outcome and the degree of recommendation of the treatment to others were both favorable (mean scores 8.6 and 8.7 out of 10, respectively). CONCLUSION: Oral rehabilitation using functional jaw reconstruction can reach a satisfactory level of esthetics, function, and psychosocial well being of patients, thus improving their quality of life.

Activities of Daily Living↗