Hessam Nowzari

Clinical and microbiological determinants of ailing dental implants.

BACKGROUND The failure of the host tissue to establish or maintain osseointegration around dental implants is due to either occlusal or parafunctional forces, premature loading, ill-directed stress, or microbial infection. The long-term failure rate of dental implants is generally 5-10%. Although a variety of etiologies of early peri-implant bone loss (from implant placement to 1-year post-loading) have been proposed, factors associated with late implant failures are less well understood but are probably related to both the peri-implant microbial environment and host factors. Discriminating between causes of implant failure is of importance for instituting a successful implant therapy. PURPOSE The objective of this cross-sectional split-mouth study was to identify clinical, radiographic, and bacterial characteristics of peri-implant disease sites. MATERIALS AND METHODS Fifteen patients with bilateral implants (Brånemark, Nobel Biocare AB, Göteborg, Sweden; and 3i implant systems, Implant Innovations Inc., Palm Beach Gardens, FL, USA) participated in the study. Sites with peri-implant (radiographic bone loss beyond the third implant thread) and peri-implant healthy tissues (radiographic bone level above the first implant thread) were identified in periapical radiographs using a long-cone paralleling projection technique. Microbiological identification was carried out using established anaerobic culture techniques. A descriptive statistics based on means and standard deviations was reported. RESULTS Peri-implant bone loss was associated with the absence of radiographic crestal lamina dura, peri-implant pocket depth, pain on chewing, and the submucosal presence of the putative periodontopathogens Tannerella forsythia, Campylobacter species, and Peptostreptococcus micros. Pain was associated with P. micros, Fusobacterium species, and Eubacterium species. DISCUSSION AND CONCLUSION The absence of radiographic crestal lamina dura and the presence of suspected major periodontal pathogens seem to be associated to peri-implantitis.

Microbiology and Cytokine Levels Around Healthy Dental Implants and Teeth

BACKGROUND Elicitation of the relationship of periodontopathogens and pro-inflammatory cytokines to bone resorption and formation is significant to a growing body of research known as osteoimmunology. It is essential that clinically healthy peri-implant and periodontal sites are studied to contribute comparison data for investigations that are addressing diseased sites. PURPOSE The purpose of this study was to describe levels of selected pro-inflammatory cytokines in clinically healthy peri-implant and periodontal sites, and to examine whether cytokine levels may be related to specific bacterial/viral pathogens. MATERIALS AND METHODS Eleven subjects (mean age 56.2 +/- 10) participated in the study. Subgingival microbial samples were cultured for periodontopathic bacteria. Gingival crevicular fluid samples were analyzed by nested polymerase chain reaction for Cytomegalovirus (HCMV) and were tested for the quantification of Interleukin (IL)-8, IL-1beta, IL-6, IL-10, Tumor Necrosis Factor (TNF)-alpha, and IL-12p70 using flow cytometry (FACS). Findings for microbiota composition and cytokine levels were compared between implants and teeth (chi square, Kruskall-Wallis, Mann-Whitney; p < or = .05). RESULTS Both the frequency (%) and levels (%) of periodontopathic bacteria were higher around teeth than implants. The concentration (picogram per milliliter) of cytokines was more prominent around implants than teeth, reaching nearly twofold differences in some instances. Cytokine levels were higher when the sites analyzed were positive for any bacteria tested. HCMV was not detected. CONCLUSIONS Pro-inflammatory cytokine production was unrelated to heavy bacterial challenge. Nevertheless, when periodontopathic bacteria were detected by culture, cytokine levels were increased around both implants and teeth. Studies are needed to investigate the pro-inflammatory cytokines (especially IL-1beta and TNF-alpha) produced in spite of minimal bacterial accumulation.

Soft tissue enhancement around dental implants

Peri-implant plastic surgery aims at improving the esthetic aspects of smile appearance and masticatory function. Enhancement of the esthetic appearance can lend significant support to patients wishing to experience more effective and successful interactions with others in personal, social and workplace situations. This article reviews pre-implant anatomic features that influence the outcome of dental implant therapy and presents a range of surgical modalities aimed at enhancing the appearance of peri-implant soft tissue.

Cone beam computed tomographic measurement of maxillary central incisors to determine prevalence of facial alveolar bone width ≥2 mm.

BACKGROUND The initial thickness of maxillary bone has significant impact on the responding level of facial bone and soft tissue after extraction and immediate implant placement. A prevailing notion is that following implant placement in fresh extraction sites, at least 2 mm of facial bone is needed to prevent soft tissue recession, fenestration, and dehiscence. PURPOSE The purpose of this study was to use cone beam computed tomography (CBCT) to measure horizontal width of facial alveolar bone overlying healthy maxillary central incisors and to determine prevalence of bone thickness ≥2 mm. MATERIALS AND METHODS Tomographic data from 101 randomly selected patients were evaluated by two independent observers. Assessments were made of facial bone width at levels 1.0 to 10.0 mm apical to the bone crest. RESULTS Healthy maxillary central incisors (n= 202) were measured from 101 patient scans. The percent of teeth with facial bone ≥2 mm at levels 1, 2, 3, 4, and 5 mm from the bone crest was 0, 1.5, 2.0, 3.0, and 2.5%, respectively. Overall mean thickness of the bone was 1.05 mm for right and left central incisors combined. The range of individual measurements for all levels was 0 to 5.1 mm. The occurrence of ≥ 2 mm thickness bone measurements increased with increasing depth. However, mean widths observed at levels 6 to 10 mm from the crest ranged only 1.0 to 1.3 mm because of apparent fenestration occurrence (0 mm bone) in approximately 12% of teeth. Overall, no significant differences in bone thickness were found between ethnic, gender, age, or scan groups. CONCLUSIONS Using CBCT, occurrences of ≥2 mm maxillary facial alveolar bone were found on no more than 3% of root surfaces 1.0 to 5.0 mm apical to the bone crest in this sample of maxillary central incisors. The study evidenced prevalence of a thin facial alveolar bone (<2 mm) that may contribute to risk of facial bone fenestration, dehiscence, and soft tissue recession after immediate implant therapy.

Risk of Prion Disease Transmission through Bovine‐Derived Bone Substitutes: A Systematic Review

BACKGROUND Despite the causal association between variant Creutzfeldt - Jakob disease and bovine spongiform encephalopathy (BSE), bovine origin graft materials are widely used during dental surgical procedures. The aim of this study was to assess the risk of BSE transmission through anorganic bovine bone substitutes. METHODS Electronic database of MEDLINE was searched to identify relevant studies regarding our focused questions, presence of BSE prion infectivity in raw bovine bone, BSE prion inactivation by bone substitute manufacturing process, protein contents in anorganic bovine bone substitutes, and validity of current BSE diagnostic methods. Search terms yielded 1,704 titles. After title/abstract screening and duplicates removal, 36 full-text articles were screened for inclusion. RESULTS A total of 16 studies were included in the final analysis. No eligible studies were identified regarding the efficacy of BSE prion inactivation by the treatments used for anorganic bovine bone manufacturing. BSE infectivity and PrP(Sc) , pathological prion, were detected in bovine bone marrow and serum samples. Proteins were detected in Tutoplast® (bovine), Bio-Oss®, and tibia samples treated at the similar condition for Bio-Oss deproteinization. Inconsistent results of different BSE diagnostic tests were not unusual findings (Iwata et al. 2006; Arnold et al. 2007; Murayama et al. 2010), and a study by Balkema-Buschmann and colleagues showed an apparent discrepancy between BSE infectivity and detection of PrP(27-30), the current surrogate marker for prion disease infectivity. CONCLUSION This review indicates that bovine-derived graft biomaterials may carry a risk of prion transmission to patients.

The Thickness of Facial Alveolar Bone Overlying Healthy Maxillary Anterior Teeth

BACKGROUND A facial bone (<2 mm) overlying maxillary anterior teeth may be prone to resorptive processes after extraction and immediate implant placement. A thin bone contributes to risk of bone fenestration, dehiscence, and soft-tissue recession. This study measures the distance between the cemento-enamel junction (CEJ) and alveolar bone crest and the thickness of facial alveolar bone at points 1 to 5 mm from the bone crest for the six maxillary anterior teeth. METHODS Sixty-six tomographic scans (31 males and 35 females; aged 17 to 69 years; mean age: 39.9 years) of intact anterior maxilla were randomly selected and evaluated by two calibrated and independent examiners (MG and TP). RESULTS A high variation of CEJ-bone crest (0.8 to 7.2 mm) was detected. A significantly larger CEJ-bone crest was measured in smokers (P <0.05) and patients who were ≥50 years old (P <0.05). The average bone thickness at 3 mm from the CEJ for the maxillary right central incisor was 1.41 mm and for the maxillary left central incisor was 1.45 mm. For the maxillary right and left lateral incisors, the crestal bone thickness averaged 1.73 and 1.59 mm, respectively. For the maxillary right and left canines, the crestal bone thickness averaged 1.47 and 1.60 mm, respectively. CONCLUSIONS The present study supports the finding of a predominantly thin facial bone overlying the six maxillary anterior teeth. Therefore, it is essential to make informed treatment decisions based on thorough site evaluation before immediate implant placement.

Quantitation of mandibular ramus volume as a source of bone grafting.

BACKGROUND When alveolar atrophy impairs dental implant placement, ridge augmentation using mandibular ramus graft may be considered. In live patients, however, an accurate calculation of the amount of bone that can be safely harvested from the ramus has not been reported. The use of a software program to perform these calculations can aid in preventing surgical complications. PURPOSE The aim of the present study was to intra-surgically quantify the volume of the ramus bone graft that can be safely harvested in live patients, and compare it to presurgical computerized tomographic calculations. MATERIALS AND METHODS The AutoCAD software program quantified ramus bone graft in 40 consecutive patients from computerized tomographies. Direct intra-surgical measurements were recorded thereafter and compared to software data (n = 10). In these 10 patients, the bone volume was also measured at the recipient sites 6 months post-sinus augmentation. RESULTS The mandibular second and third molar areas provided the thickest cortical graft averaging 2.8 +/- 0.6 mm. The thinnest bone was immediately posterior to the third molar (1.9 +/- 0.3 mm). The volume of ramus bone graft measured by AutoCAD averaged 0.8 mL (standard deviation [SD] 0.2 mL, range: 0.4-1.2 mL). The volume of bone graft measured intra-surgically averaged 2.5 mL (SD 0.4 mL, range: 1.8-3.0 mL). The difference between the two measurement methods was significant (p < 0.001). The bone volume measured 6 months post-sinus augmentation averaged 2.2 mL (SD 0.4 mL, range: 1.6-2.8 mL) with a mean loss of 0.3 mL in volume. CONCLUSION The mandibular second molar area provided the thickest cortical graft. A cortical plate of 2.8 mm in average at combined second and third molar areas provided 2.5 mL particulated volume. The use of a design software program can improve surgical treatment planning prior to ramus bone grafting. The AutoCAD software program did not overestimate the volume of bone that can be safely harvested from the mandibular ramus.

Fractal analysis of dental radiographs to detect periodontitis-induced trabecular changes.

BACKGROUND AND OBJECTIVE The aim was to evaluate fractal analysis as a tool to quantitatively measure the impact of periodontal disease on surrounding bone. The diagnosis of periodontitis is based on information obtained from clinical and radiographic examinations. The current standard use of dental radiographs is visual inspection, often with no quantitative analysis. Fractal analysis can be used to examine trabecular bone patterns among periodontal patients. MATERIAL AND METHODS Patients (n = 108) from the University of Southern California School of Dentistry were classified into three groups: healthy, moderate and severe periodontitis. A region of interest was selected from periapical radiographs. Image processing was applied to correct for lighting irregularity, and the box-counting method was used to calculate a fractal dimension. ANOVA and ANCOVA were used to measure fractal dimension differences between all groups. RESULTS According to the statistical tests, significant differences in average fractal dimensions were measured between healthy and moderate periodontitis groups (p < 0.01) and between healthy and severe periodontitis groups (p < 0.001). Higher fractal dimensions were measured in healthy periodontal patients. CONCLUSION Fractal analysis evidenced significant differences between patients affected and not affected by periodontitis. The box-counting method quantitatively describes the severity of bone disease and can be used to improve current diagnostic techniques.

Photoactivated disinfection using light-emitting diode as an adjunct in the management of chronic periodontitis: a pilot double-blind split-mouth randomized clinical trial

AIM This split-mouth double-masked randomized controlled clinical study evaluated the effectiveness of photoactivated disinfection (PAD) using light-emitting diode (LED) as an adjunct in the management of patients affected by moderate to severe chronic periodontitis. MATERIALS AND METHODS Sixteen patients affected by moderate to severe chronic periodontitis were enrolled. After scaling and root planing (SRP), each quadrant was assigned to one of the following groups: LED group (625-635 nm, maximum power density: 2000 mW/cm(2) ), photosensitizer group (tolouidine blue O, 0.1 mg/ml), PAD group (photosensitizer and LED) and control group (no adjunctive treatment). The adjunctive treatments were repeated after 7 and 14 days. The clinical parameters of bleeding on probing, probing pocket depth and clinical attachment level were measured at baseline and 1 and 3 months after SRP. RESULTS At 1 and 3 months, all groups showed significant improvements with regard to all clinical parameters compared to baseline (all p: <0.001). There were no significant differences among groups in terms of changes of clinical parameters in any time interval (all p > 0.05). CONCLUSION The application of PAD using LED with the current setting did not have additional effects on clinical parameters in patients diagnosed with moderate to severe chronic periodontitis compared with SRP alone.

The Profile of Inflammatory Cytokines in Gingival Crevicular Fluid around Healthy Osseointegrated Implants

OBJECTIVE Regardless of gingival health and subgingival microbiology, production of cytokines within peri-implant tissues may be different from that of teeth. The objective of this study was to describe the peri-implant levels of pro-inflammatory cytokines and subgingival microbiology in clinically healthy sites. MATERIALS AND METHODS Subgingival plaque and gingival crevicular fluid (GCF) were obtained from 28 clinically healthy implants and 26 teeth selected from 24 individuals. Microbial composition was determined by selective anaerobic culture techniques. Pro-inflammatory cytokines were quantified by flow cytometry analysis of GCF. The concentration of cytokines between implants and teeth were compared with the independent t-test. RESULTS The concentration of cytokines was higher in GCF from healthy implants than in teeth. The profile of cytokines was characteristic of an innate immune response. A more frequent detection of periodontopathic bacteria was observed in teeth than implants. Cultivable levels of periodontopathic bacteria were similar between implants and teeth. CONCLUSIONS Despite gingival tissue health and scarce plaque accumulation, the profile of inflammatory cytokines in implant crevicular fluid was distinctive of an innate immune response and in higher concentration than in teeth. Other than bacterial stimulus, intrinsic factors related to implants may account for more cytokine production than teeth.