Sandra K. Rich

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.

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 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.

Immunology, Microbiology, and Virology Following Placement of NobelPerfect™ Scalloped Dental Implants: Analysis of a Case Series

BACKGROUND Cytokine-microbiology-virology monitoring after implant placement may help to develop profiles of variables that can help to explain interaction between the immune system and alveolar bone. Descriptive information at the molecular and cellular levels after implant placement is important in the emerging field of osteoimmunology and may help to formulate hypotheses and intervention strategies in periodontology and implantology. PURPOSE The purpose of this study was to determine the presence or absence of selected cytokines in association with periodontopathogens and human cytomegalovirus (HCMV) after placement of dental implants. MATERIALS AND METHODS Charts of seven consecutive patients with 19 NobelPerfect (Nobel Biocare, Yorba Linda, CA, USA) implants were reviewed for crevicular fluid sample outcomes. Anaerobic culture determined periodontopathogens 2 to 5 days, 3 and 6 months postimplant insertion. At 3, 6, and 12 months, real-time reverse transcriptase-polymerase chain reaction (RT-PCR) was performed to detect active HCMV, interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (INF-gamma). RESULTS Four of five, and six of seven patients harbored no periodontopathogens at 3- or 6-month intervals, respectively. In spite of absence of a bacterial challenge, IL-1beta and TNF-alpha activity was significant. INF-gamma was not detected, and HCMV was present at one time interval only. CONCLUSIONS TNF-alpha is produced mainly in the early stages of acute inflammation, and high levels of this cytokine at 3 and 6 months postimplant placement may be related to a repetitive acute-phase inflammatory response. Lack of INF-gamma and a high cytokine presence without significant corresponding periopathogens or viruses raise a concern that inflammation and, thus, inflammatory bone destruction, is possible outside of these variables. Inflammation and bone loss around this same group of scalloped implants, reported by our previous study, may have been initiated by local factors, such as particular implant design features.