A clinical evaluation of fixed-bridge restorations supported by the combination of teeth and osseointegrated titanium implants

Abstract. The present paper reports on the result of the use of osseointegrated titanium fixtures and teeth as combined abutments for fixed-bridge restorations in 10 partially dentate patients. In these patients, the remaining teeth were too few or too unfavourably distributed in the jaws to serve as sole abutments for fixed bridgework. Titanium fixtures ad modum Brånemark were therefore implanted in suitable positions and used as abutments in combination with the remaining teeth. Evaluations at periods of 6 to 30 months postoperatively revealed good clinical results. Some tissue reactions, however, were also observed, indicating the presence of certain clinically significant differences in the functional behaviour of tooth abutments and titanium fixture abutments. These reactions and differences are discussed.     

Guided tissue regeneration in the treatment of furcation defects in mandibular molars

The present investigation was designed to evaluate the regenerative potential of the periodontal tissues in degree III furcation defects at mandibular molars using a treatment procedure based on the principle of guided tissue regeneration. The patient sample included 21 patients, 26-65 years of age, who presented periodontal lesions in the right and left molar regions including "through and through" furcation defects. After an initial examination, each patient was subjected to a series of full-mouth scaling and root planing. 2-3 months later, they were recalled for a baseline examination. The furcation-involved molars were randomly assigned in each patient to either a test or a control treatment procedure. The test procedure included the elevation of muco-periosteal flaps at the buccal and lingual aspects of the molars. Granulation tissue was removed and the exposed root surfaces were debrided and planed. The width and the height of the entrance openings to the furcation defects were assessed. A teflon membrane was adjusted to cover the entrances to the defects (buccal and lingual) and was retained in the manner described by Pontoriero et al. (1988). The flaps were repositioned on the outer surface of the membrane and secured by sutures which were removed after 10 days. Following surgery, the patients were instructed to rinse the mouth twice daily for 4 weeks with chlorhexidine gluconate. The membranes were removed after a healing period of 1-2 months. A surgical procedure identical to the test procedure was performed in the control tooth regions with the exception of the placement of membranes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intra‐oral pattern of tooth and periodontal bone loss between the age of 50 and 60 years. A longitudinal prospective study

Objective: In a 10‐year prospective study we analyzed (i) the intra‐oral pattern of and (ii) potential risk factors for tooth and periodontal bone loss in 50‐year‐old individuals. Methods: A randomized subject sample of 50‐year‐old inhabitants in the County of Värmland, Sweden, was examined at baseline and after 10 years. Data from full‐mouth clinical and radiographic examinations and questionnaire surveys of 309 (72%) of the individuals who were dentate at baseline were available for analysis. Non‐parametric tests and binary logistic multiple regression models were used for statistical analysis of the data. Results: 4.1% of the 7,101 teeth present at baseline, distributed among 39% of the subjects, were lost during the 10‐year interval. The incidence of tooth loss was highest among mandibular molars (7.5%) and lowest among canines (1.8%). The relative risk (RR) for tooth loss for endodontically compromised teeth was 4.1 and for furcation‐involved molars 2.4–6.5, depending on tooth position. Logistic regression analysis identified baseline alveolar bone level (ABL), endodontic conditions, CPITN score (Community Periodontal Index of Treatment Needs), tooth position, caries, and educational level as risk factors for tooth loss. The overall mean 10‐year ABL change was ?0.54?mm (S.E. 0.01). On a tooth level the ABL change varied between ?0.35?mm (mandibular molars) and ?0.79?mm (mandibular incisors). Smokers experienced a greater (20–131% depending on tooth type) mean bone loss than non‐smokers. The logistic regression model revealed that tooth position, smoking, and probing pocket depth ≥4?mm were risk factors for bone loss of >1?mm. No pertinent differences were observed with respect to risk factors for ABL change in the subgroup of non‐smokers compared to the results of the analysis based on the entire subject sample. Conclusion: Tooth loss was more common in the molar than in the anterior tooth regions, while periodontal bone loss had a random distribution in the dentition. The predominant risk factors identified with regard to further radiographic bone loss were ‘probing pocket depth ≥6?mm’ and ‘smoking’.     

Dynamics of Bio‐Oss® Collagen incorporation in fresh extraction wounds: an experimental study in the dog

Aim: The objective of this experiment was to analyze processes involved in the incorporation of Bio‐Oss^® Collagen in host tissue during healing following tooth extraction and grafting. Methods: Five beagle dogs were used. Four premolars in the mandible (₃P₃, ₄P₄) were hemi‐sected, the distal roots were removed and the fresh extraction socket filled with Bio‐Oss^® Collagen. The mucosa was mobilized and the extraction site was closed with interrupted sutures. The tooth extraction and grafting procedures were scheduled in such a way that biopsies representing 1 and 3 days, as well as 1, 2 and 4 weeks of healing could be obtained. The dogs were euthanized and perfused with a fixative. Each experimental site, including the distal socket area, was dissected. The sites were decalcified in EDTA, and serial sections representing the central part of the socket were prepared in the mesio‐distal plane and parallel with the long axis of the extraction socket. Sections were stained in hematoxylin and eosin and were used for the overall characteristics of the tissues in the extraction socket. In specimens representing 1, 2 and 4 weeks of healing the various tissue elements were assessed using a morphometric point counting procedure. Tissue elements such as cells, fibers, vessels, leukocytes and mineralized bone were determined. In deparaffinized sections structures and cells positive for tartrate‐resistant acid phosphatase activity (TRAP), alkaline phosphatase and osteopontin were identified. Results: The biomaterial was first trapped in the fibrin network of the coagulum. Neutrophilic leukocytes [polymorphonuclear (PMN) cells] migrated to the surface of the foreign particles. In a second phase the PMN cells were replaced by multinuclear TRAP‐positive cells (osteoclasts). The osteoclasts apparently removed material from the surface of the xenogeneic graft. When after 1–2 weeks the osteoclasts disappeared from the Bio‐Oss^® granules they were followed by osteoblasts that laid down bone mineral in the collagen bundles of the provisional matrix. In this third phase the Bio‐Oss^® particles became osseointegrated. Conclusions: It was demonstrated that the incorporation of Bio‐Oss^® in the tissue that formed in an extraction wound involved a series of different processes. To cite this article:
Araújo MG, Liljenberg B, Lindhe J. Dynamics of Bio‐Oss^® Collagen incorporation in fresh extraction wounds: an experimental study in the dog.
Clin. Oral Impl. Res. 21 , 2010; 55–64.     

Bone dimensional variations at implants placed in fresh extraction sockets: a multilevel multivariate analysis

Aim: To use multilevel, multivariate models to analyze factors that may affect bone alterations during healing after an implant immediately placed into an extraction socket. Material and methods: Data included in the current analysis were obtained from a clinical trial in which a series of measurements were performed to characterize the extraction site immediately after implant installation and at re‐entry 4 months later. A regression multilevel, multivariate model was built to analyze factors affecting the following variables: (i) the distance between the implant surface and the outer bony crest (S‐OC), (ii) the horizontal residual gap (S‐IC), (iii) the vertical residual gap (R‐D) and (iv) the vertical position of the bone crest opposite the implant (R‐C). Results: It was demonstrated that (i) the S‐OC change was significantly affected by the thickness of the bone crest; (ii) the size of the residual gap was dependent of the size of the initial gap and the thickness of the bone crest; and (iii) the reduction of the buccal vertical gap was dependent on the age of the subject. Moreover, the position of the implant opposite the alveolar crest of the buccal ridge and its bucco‐lingual implant position influenced the amount of buccal crest resorption. Conclusions: Clinicians must consider the thickness of the buccal bony wall in the extraction site and the vertical as well as the horizontal positioning of the implant in the socket, because these factors will influence hard tissue changes during healing. To cite this article:
Tomasi C, Sanz M, Cecchinato D, Pjetursson B, Ferrus J, Lang NP, Lindhe J. Bone dimensional variations at implants placed in fresh extraction sockets: a multilevel multivariate analysis.
Clin. Oral Impl. Res. 21 , 2010; 30–36.     

New concepts of destructive periodontal disease

The most common forms of destructive periodontal disease have been thought to slowly and continuously progress until treatment or tooth loss. Recently, data have become available which are inconsistent with this "continuous disease" hypothesis. Data from longitudinal monitoring of periodontal attachment levels and alveolar bone in humans and in animals suggest that periodontal disease progresses by recurrent acute episodes. In addition, rates of attachment loss have been measured in individual sites which are faster than those consistent with the continuous disease hypothesis or slower than those expected from estimates of prior loss rates. To account for these observations, a model of destructive periodontal disease is described in which bursts of activity occur for short periods of time in individual sites. These bursts appear to occur randomly at periodontal sites throughout the mouth. Some sites demonstrate a brief active burst of destructive periodontal disease (which could take a few days to a few months) before going into a period of remission. Other sites appear to be free of destructive periodontal disease throughout the individual's life. The sites which demonstrate destructive periodontal activity may show no further activity or could be subject to one or more bursts of activity at later time periods. Comparison of monitored loss rates for a year with mean loss rates prior to monitoring suggested that there may be relatively short periods in an individual's life in which many sites undergo periodontal destruction followed by periods of extended remission. An extension of the random disease model is also suggested in which bursts of destructive periodontal disease activity occur with higher frequency during certain periods of an individual's life.