Biomedical subjects

Hom-Lay Wang

Publications and source records attributed to Hom-Lay Wang.

16 recordsLinked to original sources

PubMed2003

Healing and osseointegration of submerged microtextured oral implants.

The success of dental implants is primarily dependent upon the degree of osseointegration or bone-to-implant contact (BIC), possibly facilitated by a roughened implant surface. This study was performed to histologically evaluate the nature of osseointegration and bone healing of submerged microtextured implants in eight dogs. Three months following tooth extraction in the posterior mandibulae, three microtextured submerged implants were placed in each quadrant. Block biopsies were harvested at 4 and 16 weeks (four dogs each) following surgery, and histologic preparation was performed. Histomorphometric analysis demonstrated that % BIC value increased marginally from 40% at 4 weeks to 48% at 16 weeks, without a statistically significant difference. The first bone-to-implant contact (f-BIC) at 16 weeks was significantly lower than the 4-week f-BIC (0.81 mm vs. 0.56 mm). In conclusion, this study found minimal change in BIC over time (from 4 to 16 weeks) in unloaded microtextured implants, while the mean f-BIC value significantly increased during this same observation period.

Animals↗

PubMed2003

Critical review of immediate implant loading.

BACKGROUND: Implant dentistry has become successful with the discovery of the biological properties of titanium. In the original protocol, studies have advocated a 2-stage surgical protocol for load-free and submerged healing to ensure predictable osseointegration. However, the discomfort, inconvenience, and anxiety associated with waiting period remains a challenge to both patients and clinicians. Hence, loading implant right after placement was attempted and has gained popularity among clinicians. Issues/questions related to this approach remain unanswered. Therefore, it is the purpose of this review article to (1). review and analyze critically the current available literature in the field of immediate implant loading and (2). discuss, based on scientific evidence, factors that may influence this treatment modality. MATERIAL AND METHODS: Literature published over the past 20 years was selected and reviewed. Findings from these studies were discussed and summarized in the tables. The advantages and disadvantages associated with immediate implant loading were analyzed. Factors that may influence the success of immediate implant loading, including patient selection, type of bone quality, required implant length, micro- and macrostructure of the implant, surgical skill, need for achieving primary stability/control of occlusal force, and prosthesis guidelines, were thoroughly reviewed and discussed. RESULTS AND CONCLUSION: Various studies have demonstrated the feasibility and predictability of this technique. However, most of these articles are based on retrospective data or uncontrolled cases. Randomized, prospective, parallel-armed longitudinal human trials are primarily based on short-term results and long-term follow-ups are still scarce in this field. Nonetheless, from available literature, it may be concluded that anatomic locations, implant designs, and restricted prosthetic guidelines are key to ensure successful outcomes. Future studies, preferably randomized, prospective longitudinal studies, are certainly needed before this approach can be widely used.

Bite Force↗

PubMed2003

Comparative analysis of collagen membranes for the treatment of implant dehiscence defects.

Guided bone regeneration (GBR) evolved from the concept of guided tissue regeneration (GTR) and has been used for reconstructing sites with bone deficiencies associated with dental implants. For GBR, the use of absorbable collagen membranes has been increasing, but, at present, scientific information on the use of collagen membranes for GBR is limited. This study was aimed to clinically and histomorphometrically compare two collagen membranes, Bio-Gide(R) and BioMend ExtendTM, for the treatment of implant dehiscence defects in eight mongrel dogs. Implant dehiscence defects were surgically created in edentulous ridges, followed by the placement of three endosseous implants bilaterally in the mandible. Each implant dehiscence defect was randomly assigned to one of three treatment groups: (1) control (no membrane), (2) porcine dermis collagen barrier (Bio-Gide) or (3) bovine tendon collagen barrier (BioMend Extend). Dogs were sacrificed at 4 and 16 weeks (four dogs each) after treatment. Histomorphometric analysis included percentage linear bone fill (LF), new bone-to-implant contact (BIC) and area of new bone fill (BF). The results of the study revealed no significant differences among groups for any parameter at 4 weeks. However, at 16 weeks, more LF, BIC, and BF were noted in the membrane-treated groups than controls. BioMend Extend-treated defects demonstrated significantly greater BIC than control (P < 0.05) at this time point. BIC at 16 weeks was significantly greater than 4-week BIC (P < 0.05). Membrane exposure occurred in 9 out of 15 sites examined, resulting in significantly less LF and BIC than the sites without membrane exposure (P < 0.05). The results of this study indicate that: (1) GBR treatment with collagen membranes may significantly enhance bone regeneration, manifested at late stage (16 weeks) of healing; and (2) space maintenance and membrane coverage were the two most important factors affecting GBR using bioabsorbable collagen membranes.

Absorbable Implants↗

PubMed2003

Influence of sex hormones on the periodontium.

OBJECTIVES: Sex hormones have long been considered to play an influential role on periodontal tissues, bone turnover rate, wound healing and periodontal disease progression. The objectives of this review article are to (1) address the link between sex hormones and the periodontium, (2) analyse how these hormones influence the periodontium at different life times and (3) discuss the effects of hormone supplements/replacement on the periodontium. MATERIALS AND METHODS: Two autonomous searches were performed in English language utilizing Medline, Premedline and Pubmed as the online databases. Publications up to 2002 were selected and further reviewed. In addition, a manual search was also performed including specific related journals and books. RESULTS: It is certain that sexual hormones play a key role in periodontal disease progression and wound healing. More specifically, these effects seem to differentiate by gender as well as lifetime period. In addition, the influence of sex hormones can be minimized with good plaque control and with hormone replacement. CONCLUSION: Despite profound research linking periodontal condition with sex hormones kinetics, more definitive molecular mechanisms and therapy still remain to be determined.

Alveolar Bone Loss↗

PubMed2003

Effects of specific nutrients on periodontal disease onset, progression and treatment.

OBJECTIVES: The aim of this paper is to review the available literature pertaining to the effects of specific nutritional elements (e.g. vitamin B-complex, vitamin C and dietary calcium) on general wound healing, periodontal disease status and response to periodontal therapy. METHODS: Critical appraisal of various studies that have evaluated the effects of calcium, ascorbic acid and vitamin B-complex in wound healing and periodontal treatment. RESULTS: Periodontal disease onset, progression and response to therapeutic interventions have been shown to be influenced by several systemic, local and environmental modifying factors. Nutritional supplementation has been suggested as a possible influencing factor on periodontal status and wound healing. Several studies have reported various degrees of association between nutritional elements/supplements and periodontal status, and others have reported possible positive influences of nutritional supplementation on periodontal therapeutic outcomes. Future research needs to more fully explore the presence and strength of association between nutrition and periodontal health. CONCLUSIONS: Data collected from the literature suggests that nutrient supplementation causes minimal or no side effects. However, the efficacy of prophylactic nutrient supplementation for the prevention of the onset and progression of periodontal disease, or for the enhancement of periodontal wound healing, remains to be determined.

Animals↗

PubMed2003

Interactions between the gingiva and the margin of restorations.

An adequate understanding of the relationship between periodontal tissues and restorative dentistry is paramount to ensure adequate form, function, esthetics, and comfort of the dentition. While most clinicians are aware of this important relationship, uncertainty remains regarding specific concepts such as the biologic width and indications and applications for surgical crown lengthening. This review discusses the concept of the biologic width and its relationship to periodontal health and restorative dentistry. The importance of restorative margin location, materials, and contours related to periodontal health is also addressed. The rationale and indications for surgical crown lengthening are elaborated. Particular surgical principles of crown lengthening are examined in detail.

Biology↗

PubMed2003

Management of the implant periapical lesion: a case report.

The implant periapical lesion (IPL), a possible cause for implant failure, may occur from the presence of pre-existing microbial pathology such as endodontic/periodontal lesions. This case report presents a case history related to IPL, which was caused by a pre-existing endodontic lesion. In addition, other possible causes such as surgical trauma and the management strategies of IPL are suggested. For the treatment of the infected form of IPL, a sequential surgical therapy can be utilized. This includes surgical removal of the implant or implant apical region, thorough debridement of the infected lesion, systemic antibiotics, and/or guided bone regeneration. The implant therapy should be directed to minimize the occurrence or consequences of IPL by careful diagnosis, systematic treatment planning, and appropriate treatment procedures.

Anti-Bacterial Agents↗

PubMed2002

Periodontal diseases in the child and adolescent.

BACKGROUND: Periodontal diseases are among the most frequent diseases affecting children and adolescents. These include gingivitis, localized or generalized aggressive periodontitis (a.k.a., early onset periodontitis which includes generalized or localized prepubertal periodontitis and juvenile periodontitis) and periodontal diseases associated with systemic disorders. The best approach to managing periodontal diseases is prevention, followed by early detection and treatment. METHODS: This paper reviews the current literature concerning the most common periodontal diseases affecting children: chronic gingivitis (or dental plaque-induced gingival diseases) and early onset periodontitis (or aggressive periodontitis), including prepubertal and juvenile periodontitis. In addition, systemic diseases that affect the periodontium and oral lesions commonly found in young children are addressed. The prevalence, diagnostic characteristics, microbiology, host-related factors, and therapeutic management of each of these disease entities are thoroughly discussed.

Adolescent↗

PubMed2002

Effect of initial periodontal therapy on sulcular/tongue sulfide level. A pilot study.

BACKGROUND: : Volatile sulfur compounds (VSC), such as hydrogen sulfide, methyl mercaptan and dimethyl sulfide, are toxic metabolites produced by periodontal pathogens. These VSC are also released from the tongue dorsum. Currently, limited data are available on how periodontal treatments may affect sulcular/tongue sulfide level. The aim of this study was to determine effect of initial therapy including oral hygiene instruction and scaling and root planing (SRP) on sulcular/tongue sulfide level. METHODS: : Thirteen subjects diagnosed with chronic periodontitis and having three representative periodontal pocket depth (PD) strata in one quadrant (PD or= 7.0 mm: severe disease sites) were selected. Clinical periodontal parameters were recorded at baseline and 3 weeks after completion of the initial therapy. The sulfide levels in three representative periodontal pockets (pS) and on three parts (anterior, middle, and posterior) of the tongue dorsum (tS) were measured using a commercial sulfide-monitoring device. RESULTS: : The pS levels of the three representative sites were reduced significantly following the initial therapy (p < 0.05). However, there was no significant reduction of the tS level in all three parts of the tongue. CONCLUSIONS: : The initial periodontal therapy such as oral hygiene and SRP reduces the sulcular sulfide level but not the tongue sulfide level. This suggests that sulcular sulfide level may be a possible indicator for assessing the outcome of initial periodontal treatment.

Adult↗

PubMed2002

Periodontic and orthodontic treatment in adults.

The purpose of this article is to provide an update of the interrelationship between periodontics and orthodontics in adults. Specific areas reviewed are the reaction of periodontal tissue to orthodontic forces, the influence of tooth movement on the periodontium, the effect of circumferential supracrestal fiberotomy in preventing orthodontic relapse, the effect of orthodontic treatment on the periodontium, microbiology associated with orthodontic bands, and mucogingival and esthetic considerations. In addition, the relationship between orthodontics and implants (eg, using dental implants for orthodontic anchorage) is discussed.

Adult↗

PubMed2002

The causes of early implant bone loss: myth or science?

The success of dental implants is highly dependent on integration between the implant and intraoral hard/soft tissue. Initial breakdown of the implant-tissue interface generally begins at the crestal region in successfully osseointegrated endosteal implants, regardless of surgical approaches (submerged or nonsubmerged). Early crestal bone loss is often observed after the first year of function, followed by minimal bone loss (< or =0.2 mm) annually thereafter. Six plausible etiologic factors are hypothesized, including surgical trauma, occlusal overload, peri-implantitis, microgap, biologic width, and implant crest module. It is the purpose of this article to review and discuss each factor Based upon currently available literature, the reformation of biologic width around dental implants, microgap if placed at or below the bone crest, occlusal overload, and implant crest module may be the most likely causes of early implant bone loss. Furthermore, it is important to note that other contributing factors, such as surgical trauma and penimplantitis, may also play a role in the process of early implant bone loss. Future randomized, well-controlled clinical trials comparing the effect of each plausible factor are needed to clarify the causes of early implant bone loss.

Alveolar Bone Loss↗

PubMed2002

Treatment of periodontal disease in a patient with Ehlers-Danlos syndrome. A case report and literature review.

BACKGROUND: Ehlers-Danlos syndrome (EDS) designates a heterogeneous group of connective tissue disorders characterized by skin elasticity, tissue fragility, and chronic joint pain. Dental findings have been reported with some types of EDS. This case report describes the periodontal findings in a patient with a previously undiagnosed EDS type VIII. METHODS: Diagnostic aids utilized included microbial testing, histological examination, gingival crevicular fluid (GCF) analysis for the levels of C-telopeptide pyridinoline cross-links (ICTP), and genetic counseling. Periodontal treatment consisted of mechanical debridement and adjunctive antibiotic therapy. RESULTS: Genetic counseling and clinical presentation confirmed the diagnosis of EDS type VIII. Periodontal treatment led to marked clinical improvements and GCF levels of the bone resorptive marker ICTP were significantly reduced. The patient and her siblings are currently pursuing appropriate medical care and genetic counseling. CONCLUSION: Periodontal involvement may lead to the diagnosis of an underlying systemic condition. Identification of suspected etiological factors of periodontal disease may prove critical for the general well-being of some patients.

Alveolar Bone Loss↗

PubMed2002

Comparative histologic analysis of coronally advanced flap with and without collagen membrane for root coverage.

BACKGROUND: Guided tissue regeneration (GTR)-based root coverage has been utilized to correct gingival recession defects with promising results. However, limited histologic information is available. Therefore, the aims of this study were to clinically and histologically evaluate the efficacy of GTR-based root coverage using collagen membrane (GTRC) and to compare the healing response to that of coronally advanced flaps (CAF). METHODS: Standardized gingival recession defects were surgically created on the labial surfaces of the maxillary cuspids of 8 mongrel dogs. Plaque was allowed to accumulate for 8 weeks to develop a plaque-infected recession defect. Full-mouth scaling and root planing was then performed coincident with 4 weeks of oral hygiene. Defects were randomly assigned to receive either GTRC or CAF surgery. Four dogs each were sacrificed at 4 and 16 weeks post-treatment. Clinical measurements included: percent root coverage, the amount of keratinized gingiva (KG), and probing depth (PD). Sulcular depth, junctional epithelium and connective tissue attachment, new cementum formation, and new bone formation were evaluated histomorphometrically. RESULTS: Clinically, both treatments (CAF and GTRC) achieved statistically significant (P <0.05) root coverage compared to baseline. KG was significantly increased in CAF-treated sites at 16 weeks, while no significant differences were found for other clinical parameters between treatments. Histometrically, GTRC showed a statistically significant increase of new attachment and newly formed connective tissue when compared to CAF at 16 weeks. CONCLUSION: Within the limits of this preclinical study, both GTRC and CAF can be successfully used for the treatment of gingival recession defects.

Absorbable Implants↗

PubMed2002

Use of bone grafts for the enhancement of a GTR-based root coverage procedure: a pilot case study.

The use of guided tissue regeneration (GTR) procedures for the treatment of gingival recession has shown encouraging results and is gaining clinical acceptance. However, attaining space maintenance beneath the membrane remains a problem for clinicians. Hence, the purpose of this pilot case study was to evaluate the effect of adjunctive demineralized freeze-dried bone allograft (DFDBA) placement during collagen membrane GTR-based root coverage procedures. Five patients with Miller Class I or II defects were treated with a combination of DFDBA and collagen membrane. Clinical parameters monitored include recession depth, probing attachment level, probing depth, width of keratinized gingiva, and recession width. Measurements were taken at baseline and 6 months. A statistically significant reduction in recession depth (3.1 +/- 0.7 mm) was observed at 6 months, representing 93.4% total attainable root coverage. A significant reduction of recession width (3.5 +/- 1.2 mm) after 6 months was also noted. Clinically, a statistically significant mean gain of 3.3 +/- 0.6 mm in clinical attachment and 0.8 +/- 0.9 mm in keratinized gingiva were obtained at 6 months. No statistically significant difference was found in probing depth between baseline and 6 months postoperative. Plaque and gingival indices remained low and showed no statistically significant change throughout the study period. Results from this pilot case study indicate that use of DFDBA during collagen membrane GTR-based root coverage could be beneficial.

Adult↗

PubMed2002

HVC ridge deficiency classification: a therapeutically oriented classification.

Alveolar ridge defects resulting from tooth extraction, trauma, or periodontal disease often require surgical correction prior to prosthodontic reconstruction. Whether implants or conventional fixed prostheses are planned, without careful consideration and proper treatment planning, hard and/or soft tissue defects may lead to functional, structural, or esthetic compromises in the final prosthesis. This article reviews the etiology and treatment of alveolar ridge defects and introduces a therapeutically oriented classification system of such defects (horizontal, vertical, and combination-HVC-classification). In addition, a decision-making guide for approaching each defect type will be discussed, and clinical examples of treated cases will be presented.

Alveolar Bone Loss↗

PubMedDate not supplied

Guided tissue regeneration-based root coverage utilizing collagen membranes: technique and case reports.

Gingival recession defects have traditionally been treated with various grafting procedures. Recently, guided tissue regeneration with collagen membranes has shown promising results. This article reviews the rationale, indications, contraindications, and clinical methods for the use of bioabsorbable collagen membrane barriers. Several properties make collagen membranes attractive candidates for use as barriers in guided tissue regeneration-based root coverage procedures. These include the inhibition of epithelial migration and promotion of new connective tissue attachment; the ability to aggregate platelets, thereby facilitating wound stabilization and maturation; the promotion of cellular migration and wound closure; the elimination of the need for reentry surgery; and the ability to augment tissue thickness. Cases are presented to illustrate the surgical principles and techniques.

Absorbable Implants↗