Hsun Liang Chan

Tissue biotype and its relation to the underlying bone morphology.

BACKGROUND Tissue biotypes have been linked to the outcomes of periodontal and implant therapy. The purpose of this study is to determine the dimensions of the gingiva and underlying alveolar bone in the maxillary anterior region and to establish their association. METHODS Tissue biotypes of 22 fresh cadaver heads were assessed clinically and radiographically with cone-beam computed tomography (CBCT) scans. Maxillary anterior teeth were atraumatically extracted. The thickness of both soft tissue and bone were measured using a caliper to the nearest 0.1 mm by two calibrated examiners. Probing depths and gingival recession were measured at two points (mid-labial and mid-palatal). Clinical and CBCT measurements of both soft tissue and bone thickness were subsequently compared and correlated. RESULTS No statistically significant differences were observed between the clinical and CBCT measurements of both soft tissue and bone thickness except the palatal soft tissue measurements. The labial gingival thickness was moderately associated with the underlying bone thickness measured with CBCT (R = 0.429; P <0.05). Gingival recession was not associated with the thickness of both labial gingiva and bone. CONCLUSIONS CBCT measurements were an accurate representation of the clinical thickness of both labial gingiva and bone. In addition, the thickness of the labial gingiva had a moderate association with the underlying bone radiographically.

The Significance of Keratinized Mucosa on Implant Health: A Systematic Review

BACKGROUND Whether a minimal width of keratinized mucosa (KM) is required to maintain peri-implant tissue health has been a topic of interest. This systematic review and meta-analysis aims to investigate the effect of KM on various peri-implant health-related parameters. METHODS An electronic search of five databases (from 1965 to October 2012) and a hand search of peer-reviewed journals for relevant articles were performed. Human cross-sectional or longitudinal studies with data on the relationship between the amount of KM around dental implants and various peri-implant parameters, with a follow-up period of at least 6 months, were included. RESULTS Eleven studies, seven cross-sectional and four longitudinal, were included. Weighted mean difference (WMD) and confidence interval (CI) were calculated with meta-analyses for each clinical parameter. The results showed statistically significant differences in plaque index (PI) and modified PI (WMD = -0.27, 95% CI = -0.43 to -0.11), modified gingival index (mGI) (WMD = -0.48, 95% CI = -0.70 to -0.27), mucosal recession (MR) (WMD = -0.60 mm, 95% CI = -0.85 to -0.36 mm), and attachment loss (AL) (WMD = -0.35 mm, 95% CI = -0.65 mm to -0.06 mm), all favoring implants with wide KM. However, comparisons of other parameters (bleeding on probing, modified bleeding index, GI, probing depth, and radiographic bone loss) did not reach statistically significant differences. The result of heterogeneity test showed only one parameter (AL, P value for the χ(2) test = 0.30 and I(2) test = 18%) had a low degree of heterogeneity among analyzed studies; meta-analyses of other parameters presented moderate-to-high degree of heterogeneity. Limitations of the present review include limited number of selected studies (n = 11), existence of heterogeneity and publication bias, and only English-written articles searched. CONCLUSION Based on current available evidence, a lack of adequate KM around endosseous dental implants is associated with more plaque accumulation, tissue inflammation, MR, and AL.

Dental imaging in implant treatment planning.

Objectives:Proper implant treatment planning remains the first priority for implant success. Dental imaging is an important tool to accomplish this task. Traditional radiographs provide adequate information about proposed implant sites; however, limited film size, image distortion, magnification, and a 2-D view restrict their use in some cases. The purpose of this study is to provide an update about recent advancements in implant imaging to facilitate ideal implant treatment planning. Search Strategy:A literature search was conducted using MEDLINE to identify studies related to this topic using the keywords of implant imaging, computed tomography (CT), cone beam CT (CBCT), and digital implant planning. Results:Medical CT scan produce 3-dimensional replicas of anatomical areas with high resolution and accuracy. Although this type of imaging was introduced almost 20 years ago for implant planning, until recently it is widely used in most of the advanced procedures. CBCT is an advanced version of this technique. The advantages of CBCT are its specific design for the maxillofacial region, a reduced radiation exposure, cheaper, and excellent quality of images. Today, many companies are developing these cutting-edge machines and making it possible for dentists to use in their practices. Conclusions:Coupled with converting software programs, CT/CBCT images may assist in selecting implant dimensions and predicting treatment outcomes. Understanding the up-to-date development of imaging aids could potentiate our ability in planning implant therapy.

Are Short Dental Implants (<10 mm) Effective? A Meta-Analysis on Prospective Clinical Trials

BACKGROUND This study aims to compare the survival rate of short (<10 mm) and standard (≥10 mm) rough-surface dental implants under functional loading. METHODS An electronic literature search using PubMed and Medline databases was conducted. Prospective clinical human trials, published in English from January 1997 to July 2011, that examined dental implants of <10 mm with a 12-month follow-up were included in this meta-analysis. The following data were retrieved from the included articles: the number of implants, implant dimensions, implant locations, types of prostheses, follow-up periods, and implant survival rates. Kaplan-Meier survival estimates and the hazard rates were analyzed and compared between short and standard implants. RESULTS Thirteen studies were selected, examining 1,955 dental implants, of which 914 were short implants. Short dental implants had an estimated survival rate of 88.1% at 168 months, when standard dental implants had a similar estimated survival rate of 86.7% (P = 0.254). The peak failure rate of short dental implants was found to occur between 4 and 6 years of function. This occurred at an earlier time point compared with standard dental implants, where the peak failure rate occurred between 6 and 8 years of function. CONCLUSIONS This study shows that in the long term, implants of <10 mm are as predictable as longer implants. However, they fail at an earlier stage compared with standard implants.

Sinus pathology and anatomy in relation to complications in lateral window sinus augmentation

Antral pathoses and anatomical variations increase the risk of surgical complications during a lateral window sinus augmentation procedure. Therefore, an understanding of maxillary sinus diseases and anatomies is imperative. In the first part of this article, common sinus diseases will be reviewed, which include acute/chronic rhinosinusitis, mucoceles, pseudocysts, retention cysts, and odontogenic diseases of the maxillary sinus. In addition, a treatment strategy will be proposed toward the management of these antral diseases. In the second part, anatomical variations of the maxillary sinus, for example, the septum and artery that is in approximation to the osteotomy site will be discussed. Knowledge of diagnosing and managing sinus pathoses and anatomies could assist surgeons in reducing the incidence of sinus augmentation complications.

Surgical Management of Peri-Implantitis: A Systematic Review and Meta-Analysis of Treatment Outcomes

BACKGROUND This systematic review was requested by the Task Force of the American Academy of Periodontology as a follow-up study of the 2013 report, with an aim to investigate the efficacy of different surgical approaches to treat peri-implantitis. METHODS A search of four electronic databases from January 1990 to May 2013 was performed. Studies included were human clinical trials published in English that applied surgeries for treating peri-implantitis. Parameters evaluated included probing depth (PD) reduction, clinical attachment level gain, bleeding on probing (BOP) reduction, radiographic bone fill (RBF), and mucosal recession. The weighted mean (WM) and the 95% confidence interval of the studied parameters were estimated with the random-effect model. RESULTS A total of 1,306 studies were initially identified, after reviewing titles, abstracts, and full texts, and 21 articles, 12 of which were case series, were finally included. Four treatment groups were identified: 1) access flap and debridement; 2) surgical resection; 3) application of bone grafting materials; and 4) guided bone regeneration. The mean initial PD ranged from 4.8 to 8.8 mm, with initial BOP ranging from 19.7% to 100%. Short-term follow-ups (3 to 63 months) revealed that the available surgical procedures yielded a WM PD reduction of 2.04 (group 2) to 3.16 mm (group 4), or 33.4% to 48.2% of the initial PD. The WM RBF was 2.1 mm for groups 3 and 4. CONCLUSIONS Within the limitation of this systematic review, the application of grafting materials and barrier membranes resulted in greater PD reduction and RBF, but there is a lack of high-quality comparative studies to support this statement. The results might be used to project treatment outcomes after surgical management of peri-implantitis.

Alterations in bone quality after socket preservation with grafting materials: a systematic review.

PURPOSE While the ability of various grafting materials to preserve extraction socket morphology has been adequately reviewed, the quality of the grafted bone in the socket is not as well understood. This systematic review aimed to compare the proportion of vital bone and connective tissue between grafted and naturally healed sockets. MATERIALS AND METHODS An electronic search of five databases (from 1965 to November 2011) and a hand search of peer-reviewed journals for relevant articles were performed. Human clinical trials that compared histologic components of soft and hard tissues in augmented sockets and naturally healed sites, with at least five samples per group, were included. RESULTS Eight studies (five randomized controlled trials and three controlled clinical trials) were included. The mean percentages of vital bone and connective tissue in natural healing sockets were 38.5% ± 13.4% and 58.3% ± 10.6%, respectively. Limited evidence (one to two articles for each material) implied that vital bone fraction was not different with demineralized allografts and autografts and increased by 6.2% to 23.5% with alloplasts in comparison to nongrafted sites. Four studies investigating the effect of xenografts were available, with equivocal results. The difference in the mean percentage of vital bone ranged from -22.2% (decrease) to 9.8% (increase). Connective tissue content decreased with the use of the aforementioned bone substitutes. Considerable residual hydroxyapatite and xenograft particles (15% to 36%) remained at a mean of 5.6 months after socket augmentation procedures. CONCLUSIONS Based on a limited number of prospective comparative studies, the use of grafting materials for socket augmentation might change the proportion of vital bone in comparison to sockets allowed to heal without grafting. Whether these changes in bone quality will influence implant success and peri-implant tissue stability remains unknown.

Risk assessment of lingual plate perforation in posterior mandibular region: a virtual implant placement study using cone-beam computed tomography.

BACKGROUND Lingual plate perforation at the time of implant placement in posterior mandible is a potential surgical complication, and presence of a lingual concavity is considered a risk factor. Little is known about the spatial relationship between implant and lingual plate. The role of lingual concavity in the risk of lingual perforation has not yet been fully studied. This computer-simulated study investigates the incidence of lingual plate perforation in edentulous mandibular first molar region and the risk of perforation in the area of lingual concavity. METHODS One hundred and three qualified cone-beam computed tomography scans were selected from the database. Implants of various dimensions were virtually placed into the area using computer software. The distance between implant tip and lingual plate was measured using a digital caliper. Incidence of lingual plate perforation and proximity of the implant tip to lingual plate were measured for three types of cross-sectional mandibular morphology. RESULTS One hundred and three cone-beam computed tomography scans with 118 sites were available for analysis. The intraexaminer and interexaminer agreements were 0.93 and 0.89, respectively. The predicted incidence of lingual plate perforation was 1.1% to 1.2%. Most implants, which were within 1 mm from lingual plate, occurred in sites with lingual concavity (type-U ridge). CONCLUSIONS This study demonstrates a novel experimental design by which the spatial relation between implant and lingual plate in mandibular first molar region is investigated. Incidence of lingual plate perforation during implant placement is predicted to be 1.1% to 1.2% and it will most likely happen in type-U ridge.

Effect of the Timing of Restoration on Implant Marginal Bone Loss: A Systematic Review

BACKGROUND The advancement in implant dentistry has allowed shortened treatment time by restoring the implants earlier. Whether the timing of restoration has an impact on implant marginal bone level has not been systematically analyzed. The aim of this study is to compare marginal bone loss (MBL) between implants that were restored with the following protocols: 1) immediate restoration/loading (IR/L); 2) early loading (EL); and 3) conventional loading (CL). METHODS An electronic literature search from three databases (until November 2011) and a hand search in implant-related journals were conducted. Clinical human studies in English language that had reported a comparison of MBL between implants with IR/L, EL, or CL with ≥12-month follow-up were included. In addition, the minimal number of implants had to be 10 for each group. Implants with both immediate placement (IP) and delayed placement (DP) were included and analyzed separately. An assessment of the publication bias for the included randomized clinical trials (RCTs) was performed. RESULTS The initial search resulted in 1,640 articles, of which 27 articles in full text were further evaluated for eligibility. Finally, 11 studies (eight RCTs, two controlled clinical trials, and one retrospective study) were qualified and classified into four groups: 1) IR/L + DP versus CL + DP (n = 6 articles); 2) IR + DP versus EL + DP (n = 2 articles); 3) EL + DP versus CL + DP (n = 1 article); and (4) IL + IP versus CL + IP (n = 2 articles). A meta-analysis performed for group 1 showed 0.09 mm (95% confidence interval = -0.27 to 0.09 mm) difference in the mean MBL, favoring the IR/L protocol but without significant difference (P = 0.33). No significant difference in MBL was found for groups 2 through 4 after adjusting for the implant placement level. The eight RCTs were determined to be at moderate-to-high risk of publication bias. CONCLUSIONS This meta-analysis does not show an effect of the timing of restorations on implant MBL. The selection of restoration protocols should be based on factors other than MBL.

The Accuracy of Identifying the Greater Palatine Neurovascular Bundle: A Cadaver Study

BACKGROUND The palate is a common site for harvesting subepithelial connective tissue grafts (SCTG). The size of SCTG that can be harvested is dictated by the position of the greater palatine neurovascular bundle (GPB). The aims of this cadaver study are to assess the accuracy of predicting the location of the GPB on study models and to evaluate anatomic factors that might influence the predictability. METHODS Eleven fully dentate or partially edentulous maxillary cadavers were used. Study models were fabricated after the greater palatine foramen was identified. The GPB was recognized after dissection, from which the distance to the cemento-enamel junction of the first molar and premolar was measured. Eight periodontists and twelve periodontal residents were asked to estimate the location of the GPB on the study models and the same measurements were taken. Comparisons of the estimated and true GPB position were performed. The correlation between the palatal vault height and the variability of detecting the GPB was investigated. RESULTS The most frequent greater palatine foramen location was between the second and third molars (66.6%). For most cases, there was an underestimation of the location of the GPB up to 4 mm. The interexaminer variability was positively correlated with the vault height. CONCLUSIONS The estimated location of the GPB was commonly closer to the cemento-enamel junction of posterior teeth. Agreement on the location of the GPB was lowered with the presence of high palatal vaults. The results of this study could assist clinicians in planning the location for harvesting SCTG on the hard palate.