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Objectives: Peri‐implantitis (PI) is caused by bacteria in the peri‐implant space but the consensus on microbial profile is still lacking. Current microbial sampling of PI lesions has largely focused on analyzing bacterial species that have been shed from the implant surface and captured in the pocket fluid. The purpose of the present study was to investigate the morphotypes of bacteria in biofilm covering the implant threads and explore whether certain morphotypes were associated with PI. Methods: Fourteen failed implants were removed and instantly processed for scanning electron microscope analysis. The implants were imaged at three equally divided sub‐crestal levels of the exposed area. Bacterial morphotypes were identified and quantified by three examiners. Mobility and years in function were correlated to the presence of different morphotypes. Results: The implants demonstrated the presence of variable bacterial morphotypes that did not correlate to disease progression in our study. Some implants were dominated by filaments and others showed the presence of combinations of cocci/rods or spirilles/spirochetes. In general, all implants showed variable morphologic biofilm composition. However, individual implants tended to have similar composition throughout the entire implant. Rods and filaments were dominant morphotypes throughout the surfaces and cocci showed increased presence toward the apical third. There were some differences in the biofilm morphology with mobility and time in function. Conclusions: The profiles of bacterial biofilm morphotypes in failing implants with similar clinical presentations were highly variable. While there were significant differences between implants, similar morphotypes in individual implants were often found throughout the entire surface. [ABSTRACT FROM AUTHOR]

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Tooth enamel has the highest degree of biomineralization of all vertebrate hard tissues. During the secretory stage of enamel formation, ameloblasts deposit an extracellular matrix that is in direct contact with the ameloblast plasma membrane. Although it is known that integrins mediate cell-matrix adhesion and regulate cell signaling in most cell types, the receptors that regulate ameloblast adhesion and matrix production are not well characterized. We hypothesized that αvβ6 integrin is expressed in ameloblasts where it regulates biomineralization of enamel. Human and mouse ameloblasts were found to express both b6 integrin mRNA and protein. The maxillary incisors of Itgb6-/- mice lacked yellow pigment and their mandibular incisors appeared chalky and rounded. Molars of Itgb6-/- mice showed signs of reduced mineralization and severe attrition. The mineral-to-protein ratio in the incisors was significantly reduced in Itgb6-/- enamel, mimicking hypomineralized amelogenesis imperfecta. Interestingly, amelogenin-rich extracellular matrix abnormally accumulated between the ameloblast layer of Itgb6-/- mouse incisors and the forming enamel surface, and also between ameloblasts. This accumulation was related to increased synthesis of amelogenin, rather than to reduced removal of the matrix proteins. This was confirmed in cultured ameloblast-like cells, in which αvβ6 integrin was not an endocytosis receptor for amelogenins, although it participated in cell adhesion on this matrix indirectly via endogenously produced matrix proteins. In summary, integrin αvβ6 is expressed by ameloblasts and it plays a crucial role in regulating amelogenin deposition and/or turnover and subsequent enamel biomineralization. [ABSTRACT FROM AUTHOR]

The aim of this paper was to determine the torque resistance of this new implant during placement in different types of bone, immediate placement into sockets, and in grafted bone. The torque at time of placement serves as an indication of initial stability, which is accepted as an important factor for implant osseointegration and immediate loading. Within a 13-month period, 140 NobelActive implants in 84 consecutive patients were placed into types I-IV bone in fresh sockets, and into grafted bone (both in maxillary sinuses and on the facial alveolar surfaces where bone had been lost). The final torque was measured with a manual torque control wrench as manufactured by Nobel Biocare for clinical use with this type of implant. One hundred forty implants with 3.5 to 5 mm diameters and 10 to 15 mm lengths were placed in different types of bone, either as delayed or immediate implants into fresh extraction sockets. These implants demonstrated a mean torque stability value of 50.8 Ncm. The average insertion torque for delayed implants was 49.7 Ncm. For immediate implants the average torque was 52.6 Ncm. Placement into soft bone was also favorable at an average of 47.9 Ncm. Typical straight walled and tapered implants generally exhibit 10 to 35 Ncm insertion torques. The NobelActive implant consistently reaches higher torque levels. This may indicate they are more favorably suited to early provisionalization and loading. Soft bone (type IV) did not seem to decrease significantly the torque of insertion of these implants. Further longer term studies are needed to investigate whether this indeed makes these implants more suited for early provisionalization and loading than traditional root form. Long term studies are also needed to investigate maintenance of bone levels surrounding these implants. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to (1) introduce the features of this new implant, (2) investigate the clinical benefits as advertised by the manufacturer in comparison with traditional root form implants, and (3) provide guidelines for its use. One hundred seven NobelActive implants were placed in 67 consecutive patients with type I-IV bone within 8 months. Cases also include implants placed in sinus grafts, ridges with insufficient thickness and facial bone loss and were placed with delayed and immediate loading. Parameters were assessed to determine whether we could confirm the manufacturer's statements on this implant system. Results obtained with 107 implants of 3.5, 4.3, and 5 mm diameters with 10- to 15-mm lengths placed in different types of bone with delayed and immediate loading demonstrated a final insertion torque from 15 to 70 Ncm. All types of bone allowed "redirection" of the implant but were limited in the bone with higher density. According to the manufacturer, this new design of the NobelActive implant has high initial stability, bone condensing properties, redirecting capability, built-in platform shifting, and dual-function prosthetic connections. After investigating these 5 statements within the limits of our study, we were able to confirm these claims, but with some recommendations for the clinical use and placement of these implants. [ABSTRACT FROM AUTHOR]

Scar formation is a common, unwanted result of wound healing in skin, but the mechanisms that regulate it are still largely unknown. Interestingly, wound healing in the oral mucosa proceeds faster than in skin and clinical observations have suggested that mucosal wounds rarely scar. To test this concept, we created identical experimental wounds in the oral mucosa and skin in red Duroc pigs and compared wound healing and scar development over time. We also compared the pig oral mucosal wound healing to similar experimental wounds created in human subjects. The findings showed significantly reduced scar formation at both clinical and histological level in the pig oral mucosa as compared with skin 49 days after wounding. Additionally, the skin scars contained a significantly increased number of type I procollagen immunopositive cells and an increased fibronectin content, while the oral mucosal wounds demonstrated a prolonged accumulation of tenascin-C. Furthermore, the pig oral mucosal wounds showed similar molecular composition and clinical and histological scar scores to human oral mucosal wounds. Thus, the reduced scar formation in the pig oral mucosa provides a model to study the biological processes that regulate scarless wound healing to find novel approaches to prevent scar formation in skin. [ABSTRACT FROM AUTHOR]

Background: The association of aggressive periodontitis with Kindler syndrome was based on a single case in 1996 and later confirmed with a larger population. Since then, significant research has greatly increased our understanding of the molecular pathology of this disorder. We review recent advances in the molecular mechanisms of the syndrome and present a maintenance case report of a patient who has been followed in our clinic. Methods: A female patient who was diagnosed with Kindler syndrome and aggressive periodontitis at the age of 16 years has been followed and treated in our clinic for 12 years. Her main treatment has been maintenance therapy following her initial treatment and restorative work previously documented. Gingival biopsies obtained during the recent extraction of hopeless maxillary molars were used for histologic assessment of gingival tissue attachment apparatus and to isolate gingival fibroblasts. Reverse transcription-polymerase chain reaction (RT-PCR) was performed using these cells to confirm the lack of expression of kindlin-1. Results: RT-PCR showed the total loss of kindlin-1 mRNA in cultured gingival fibroblasts, supporting the clinical diagnosis of Kindler syndrome. Tissue biopsies revealed atypical pocket epithelium. Maintenance therapy has been moderately successful. Teeth that were recently lost had a poor prognosis at the initial assessment. The patient's gingiva and oral mucosa continue to be fragile with episodes of sloughing and inflammation. Conclusions: Periodontitis in Kindler syndrome responds to maintenance therapy, but the gingiva and oral mucosa continue to display an abnormal appearance with white patches. Histologic findings suggest that the junctional epithelium in Kindler syndrome may be abnormal and could explain why these patients have periodontal disease. Attachment loss progressed around teeth with an initial guarded or poor prognosis. Teeth that started with a good or fair prognosis continue to have a fair prognosis. Limited dental implant treatment is being considered. [ABSTRACT FROM AUTHOR]

Background: Gingiva is composed of attached and marginal (free) gingiva and interdental papilla. Increasing esthetic demands in dentistry have created a need to restore all parts of the gingiva. However, the interdental papilla has limited regeneration potential compared to other parts of the gingiva. It also is more susceptible to glngival overgrowth, suggesting that it has distinct cellular and molecular properties from other parts of the gingiva. Very little is known about the possible differences in the molecular composition of different parts of the gingiva. Methods: We compared the expression of a set of key molecules in interdental papilla and marginal gingiva from seven healthy subjects by immunohistochemical staining. Results: In the interdental papilla, immunoreactivity for integrin αvβ6 and cytokeratin 19 in the oral epithelium was significantly higher than in marginal gingiva. Expression of type I procollagen, extra domain A (EDA) and extra domain B (EDB) fibronectin isoforms, tenascin-C, transforming growth factor-β (TGF-β), connective tissue growth factor (CTGF), and the signaling molecule son-of-sevenless (SOS)-1 also were increased in the interdental papilla. The expression of small leucine-rich proteoglycans decorin, biglycan, fibromodulin, and lumican in the interdental papilla was partially different from the marginal gingiva. Conclusions: Molecular composition of the interdental papilla is distinct from marginal gingiva. Increased expression of molecules normally induced in wound healing (αvβ6 integrin, fibronectin-EDB and -EDA, tenascin-C, type I procollagen, TGF-β, CTGF, and SOS 1) suggests that the cells in the interdental papilla are in an activated state and/or inherently display a specific phenotype resembling wound healing. J Periodontol 2007;78:304-314. [ABSTRACT FROM AUTHOR]

Theoretical, numerical and experimental methods are used to develop a comprehensive understanding of how cell shape affects the mechanical characteristics of two-dimensional aggregates such as epithelia. This is an important step in relating the mechanical properties of tissues to those of the cells of which they are composed. Statistical mechanics is used to derive formulas for the in-plane stresses generated by tensions γ along cell-cell interfaces in sheets with anisotropic cellular fabric characterized by average cell aspect ratio κ . These formulas are then used to investigate self-deformation (strain relaxation) of an anisotropic sheet composed of cells of thickness h and having effective viscosity μ . Finite element simulations of epithelia and of isolated cells and novel relaxation studies of specimens of embryonic epithelia reported herein are consistent with the predictions of the theory. In all cases, geometric factors cause the relaxation responses to be more complex than a single decaying exponential. [ABSTRACT FROM AUTHOR]

The case report describes placement of an implant in the posterior maxilla so as to avoid a pneumatized sinus and also to avoid the need for a sinus lift procedure. An 81-year-old woman presented with an edentulous span in the upper right posterior maxilla. She had been missing teeth in this area for many years, and there was a combination of resorption of the alveolar ridge and pneumatization of the maxillary sinus. Eleven years previously, implants had been placed anterior to this region, but the patient was told that implants could not be placed posteriorly unless a sinus lift was done. At the time of the current presentation she was still unwilling to undergo a sinus lift procedure but wanted to know if implants could be placed in the posterior right maxilla. A tomogram obtained with a radiographic stent in place indicated that there was insufficient bone height to allow placement of implants at the usual angulation without a sinus lift. Therefore, to avoid the need for a sinus lift, 2 implants were placed with palatal angulation as guided by tomographically determined surgical stent. The treatment planning and surgical and restorative techniques are reviewed here. A favourable for the patient and the clinicians. In the situations where there is sufficient palatal bone medial to the maxillary sinus, placing implants at an angle may prevent the need for a sinus lift procedure, assuming that proper development of an occlusal restorative scheme is possible. [ABSTRACT FROM AUTHOR]

Background: Little is known about the onset and prevalence of periodontal disease in patients with the rare Kindler syndrome, a genodermatological disorder. This study investigated the level of clinical periodontal attachment in relation to age and presence of putative periodontopathogenic bacteria in individuals with Kindler syndrome. Methods: Eighteen individuals diagnosed with Kindler syndrome and 13 control subjects, aged 4 to 37 years, from rural Panama received a limited clinical periodontal examination. Subgingival samples were collected for identification of putative periodontal pathogens by polymerase chain reaction. Results: Mild to severe gingivitis was a common finding in all adults of the study population. Seventy-two percent (13/18) of the Kindler patients and 46% (6/13) of the control subjects showed mild to severe periodontal disease (P= 0.001, chi-square test). The onset of periodontitis was earlier and the progression occurred at a faster rate in the Kindler group. There was a strong correlation (r = 0.83) between the level of attachment loss and age in the Kindler group and a weaker correlation (r = 0.66) in the control group. The appearance of gingival tissues suggested atypical periodontitis with spontaneous bleeding and fragile, often desquamative, gingiva. In periodontitis patients, Porphyromonas gingivalis and Dialister pneumosintes tended to occur more frequently in control individuals compared to those with Kindler syndrome. Conclusions: In the Kindler group, periodontitis had an onset in early teenage years and progressed more rapidly compared to non-Kindler individuals of the same geographic and ethnic group. Clinical and microbiological findings suggest atypical periodontitis in Kindler patients. We propose to include Kindler syndrome in the category of medical disorders predisposing to destructive periodontal disease. [ABSTRACT FROM AUTHOR]

Background: Various approaches to treating the periodontal condition associated with Papillon-Lefèvre syndrome have been reported. These include oral hygiene instruction, use of mouthrinses, frequent debridement, multiple antibiotic regimens, periodontal surgery, extraction of hopeless teeth, and extraction of all deciduous teeth. Because Papillon-Lefèvre syndrome is rare, most publications are case reports, and very few document long-term successful treatment of the periodontal condition. Methods: In 1986, a 3.5-year-old Indo-Canadian male was diagnosed with Papillon-Lefèvre syndrome and began periodontal treatment. Initial therapy consisted of debridement every 3 weeks, a 0.12% chlorhexidine mouthrinse, 2 regimens of metronidazole, and oral hygiene instruction for his parents. After 10 months it became apparent that the treatment was having little beneficial effect, since the periodontal destruction continued and teeth 51 and 61 exfoliated. At age 4, all remaining deciduous teeth were extracted and complete dentures inserted for the following 2-year edentulous period; then a 3-month maintenance schedule was maintained. Results: The patient is now 17 years old and all his adult teeth are present with the exception of the third molars. His oral hygiene varies between moderate and good, with his most recent plaque score at 80% effectiveness. There are no probing depths greater than 4 mm, with the exception of the distal of the lower second molars where opercula are present. Conclusions: Extraction of all the deciduous teeth followed by a period of edentulousness may partially explain the fact that there has been no recurrent attachment loss in the permanent teeth up to age 17. Other explanations are discussed as part of the literature review of Papillon-Lefèvre syndrome. [ABSTRACT FROM AUTHOR]

Background: Historically, animal models for the study of periodontal diseases have incorporated surgically created defects, plaque retentive ligatures, as well as soft and high-sucrose diets which may not accurately reflect progression of the natural disease. Spontaneous periodontal disease is seen in a few animal species, but these are often expensive to maintain and are unsuitable for manipulation using advanced molecular biology techniques. Mice are inexpensive, easy to maintain, and are routinely used for transgenic experiments and are therefore an optimal animal for research purposes. However, it is commonly accepted that mice do not spontaneously develop periodontal disease. The purpose of this study was to determine if a mouse population that exhibits periodontal breakdown in the wild could be found, allowing for genetic manipulation of naturally occurring periodontal disease. Methods: We examined over 2,500 dry skulls of several Peromyscus species from various locations and habitats on the west coast of North America for periodontal bone loss in the molars, using furcation involvement as an indicator of disease severity. Alveolar bone loss was classified as Grade I) horizontal component of bone loss in the furcations; II) through-and-through furcations; and III) through-and-through furcations with alveolar bone loss into the apical third of the root. Results: The proportions of individual mice experiencing bone loss were 3.8% for Class I-III involvement, 1.3% for Class II-III involvement, and 0.5% for Class III alone. Three subspecies of P. keeni and one subspecies of P. maniculatus had periodontal disease prevalences in 7% to 13.5% of their samples. Mice from isolated islands had 1.8- to 4.7-fold higher disease prevalence than those located on the mainland, with even greater prevalence on small islands. No statistically significant differences between genders were found. Conclusions: It appears that periodontal disease is far more common in this mouse genus than previously believed. Some of the subspecies demonstrated severe periodontal disease at a prevalence comparable to that found in humans. [ABSTRACT FROM AUTHOR]

Until recently, the accepted standard for the classification of periodontal diseases was the one agreed upon at the 1989 World Workshop in Clinical Periodontics. This classification system, however, had its weaknesses. In particular, some criteria for diagnosis were unclear, disease categories overlapped, and patients did not always fit into any one category. Also, too much emphasis was placed on the age of disease limited to the gingiva existed. In 1999, an International Workshop for a Classification of Periodontal Diseases and Conditions was organized by the American Academy of Periodontology to address these concerns and to revise the classification system. The workshop proceedings have been published in the Annals of Periodontology. The major changes to the 1989 proceedings and the rationale for these changes are summarized here. In addition, the potential impact of these changes is discussed. [ABSTRACT FROM AUTHOR]

Traditionally, periodontal hand instruments are honed or sharpened during patient care as they dull easily during contact with enamel, calculus and cementum. This approach is taught in dental and hygiene schools around the world and remains the standard of care. Recently, some professional organizations have questioned whether this practice should be abandoned because of safety issues. Questions have been raised whether sharpening stones can be properly sterilized and whether the sharpening of contaminated instruments poses a health hazard for the provider. Using bacteria culture techniques and scanning electron microscopy, we tested whether contaminated ceramic sharpening stones can be sterilized. Our results demonstrate that the stones were sterile after being subjected to the manufacturer's sterilization protocol. In addition, over the last year, no incidents related to periodontal instrument sharpening have been reported among nearly 400 students at the faculty of dentistry, University of British Columbia, where chair-side sharpening is taught. Therefore, we conclude that ceramic sharpening stones can be sterilized using normal office protocols and that chair-side sharpening adds little risk beyond routine handling of operatory or periodontal instruments during patient care when proper protocols are followed. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to an article on cracked tooth syndrome by Christopher D. Lynch and Robert J. McConnell in the September 2002 issue.

Traditionally, periodontal hand instruments are honed or sharpened during patient care as they dull easily during contact with enamel, calculus and cementum. This approach is taught in dental and hygiene schools around the world and remains the standard of care. Recently, some professional organizations have questioned whether this practice should be abandoned because of safety issues. Questions have been raised whether sharpening stones can be properly sterilized and whether the sharpening of contaminated instruments poses a health hazard for the provider. Using bacteria culture techniques and scanning electron microscopy, we tested whether contaminated ceramic sharpening stones can be sterilized. Our results demonstrate that the stones were sterile after being subjected to the manufacturer's sterilization protocol. In addition, over the last year, no incidents related to periodontal instrument sharpening have been reported among nearly 400 students at the faculty of dentistry, University of British Columbia, where chair-side sharpening is taught. Therefore, we conclude that ceramic sharpening stones can be sterilized using normal office protocols and that chair-side sharpening adds little risk beyond routine handling of operatory or periodontal instruments during patient care when proper protocols are followed.

Our research group is comparing clinical, histological and molecular healing profiles of oral and skin wounds using human and pig models. The goal is to determine the molecular cues that lead to scarless healing in the oral mucosa and use that information to develop scar prevention therapies for skin and prevent aberrant wound healing in the oral cavity. Wound healing in human and pig palatal mucosa is almost identical, and scar formation is reduced in oral wounds compared with skin. The striking difference between these tissues is transient and rapidly resolving inflammation in oral wounds compared with long-lasting inflammation in the skin wounds. Currently, we are looking at wound transcriptomes (genes differentially regulated) and proteomes (a set of proteins) to investigate how these wound healing responses in skin and oral mucosa are regulated at the molecular level.

Oral mucosal wounds heal with reduced scar formation compared with skin. The epithelial integrin alphavbeta6 is induced during wound healing, and it can activate fibrogenic transforming growth factor beta1 (TGF-beta1) and anti-fibrogenic TGF-beta3 that play key roles in scar formation. In this study, expression of beta6 integrin and members of the TGF-beta pathway were studied in experimental wounds of human gingiva and both gingiva and skin of red Duroc pigs using real-time PCR, gene microarrays, and immunostaining. Similar to human wounds, the expression of beta6 integrin was induced in the pig wounds 7 days after wounding and remained upregulated >49 days. The alphavbeta6 integrin was colocalized with both TGF-beta isoforms in the wound epithelium. Significantly higher expression levels of beta6 integrin and TGF-beta1 were observed in the pig gingival wounds compared with skin. Early gingival wounds also expressed higher levels of TGF-beta3 compared with skin. The spatio-temporal colocalization of alphavbeta6 integrin with TGF-beta1 and TGF-beta3 in the wound epithelium suggests that alphavbeta6 integrin may activate both isoforms during wound healing. Prolonged expression of alphavbeta6 integrin along with TGF-beta3 in the gingival wound epithelium may be important in protection of gingiva from scar formation.

This case report describes placement of an implant in the posterior maxilla so as to avoid a pneumatized sinus and also to avoid the need for a sinus lift procedure. An 81-year-old woman presented with an edentulous span in the upper right posterior maxilla. She had been missing teeth in this area for many years, and there was a combination of resorption of the alveolar ridge and pneumatization of the maxillary sinus. Eleven years previously, implants had been placed anterior to this region, but the patient was told that implants could not be placed posteriorly unless a sinus lift was done. At the time of the current presentation she was still unwilling to undergo a sinus lift procedure but wanted to know if implants could be placed in the posterior right maxilla. A tomogram obtained with a radiographic stent in place indicated that there was insufficient bone height to allow placement of implants at the usual angulation without a sinus lift. Therefore, to avoid the need for a sinus lift, 2 implants were placed with palatal angulation as guided by a tomographically determined surgical stent. The treatment planning and surgical and restorative techniques are reviewed here. A postoperative tomogram was obtained to determine the final position of the implants. The outcome has been favourable for the patient and the clinicians. In situations where there is sufficient palatal bone medial to the maxillary sinus, placing implants at an angle may prevent the need for a sinus lift procedure, assuming that proper development of an occlusal restorative scheme is possible.