Biomedical subjects

Jan Lindhe

Publications and source records attributed to Jan Lindhe.

At least 19 recordsLinked to original sources

PubMed2007

Morphogenesis of the peri-implant mucosa: an experimental study in dogs.

PURPOSE: The objective of the present experiment was to study the morphogenesis of the mucosal attachment to implants made of c.p. titanium. MATERIAL AND METHODS: All mandibular premolars were extracted in 20 Labrador dogs. After a healing period of 3 months, four implants (ITI Dental Implant System) were placed in the right and left sides of the mandible. A non-submerged implant installation technique was used and the mucosal tissues were secured to the conical marginal portion of the implants with interrupted sutures. The sutures were removed after 2 weeks and a plaque control program including daily cleaning of the remaining teeth and the implants was initiated. The animals were sacrificed and biopsies were obtained at various intervals to provide healing periods extending from Day 0 (2 h) to 12 weeks. The mandibles were removed and placed in the fixative. The implant sites were dissected using a diamond saw and processed for histological analysis. RESULTS: Large numbers of neutrophils infiltrated and degraded the coagulum that occupied the compartment between the mucosa and the implant during the initial phase of healing. At 2 weeks after surgery, fibroblasts were the dominating cell population in the connective tissue interface but at 4 weeks the density of fibroblasts had decreased. Furthermore, the first signs of epithelial proliferation were observed in specimens representing 1-2 weeks of healing and a mature barrier epithelium occurred after 6-8 weeks of healing. The collagen fibers of the mucosa were organized after 4-6 weeks of healing. CONCLUSION: It is suggested that the soft-tissue attachment to implants placed using a non-submerged installation procedure is properly established after several weeks following surgery.

Animals↗

PubMed2006

A three-year prospective study of adult subjects with gingivitis. I: clinical periodontal parameters.

AIM: The objective of this study was to monitor prospectively clinical parameters in subjects without signs of destructive periodontal disease who were involved in a primary prevention programme, and to determine the changes that occurred between yearly examinations over a 3-year period. MATERIAL AND METHODS: One hundred and twenty-six subjects aged at least 20 years with a maximum of two tooth sites with probing pocket depth (PPD)>4 mm and no proximal sites with clinical attachment loss participated in the study. Primary prevention was provided at baseline of the study and then every 6 months. Plaque, bleeding on probing (BoP) and PPD were scored at baseline, 1, 2 and 3 years. RESULTS: There were no significant changes in the plaque score over the 3 years. After year 1, the BoP score was significantly improved with 5.6%, while no further improvement in BoP was found at years 2 and 3. The mean PPD decreased from 2.3 to 2.1 mm over the 3 years (p<0.05). CONCLUSION: Although some individuals exhibiting minor signs of periodontal pathology may have benefited from the primary prevention, the overall clinical improvement was limited for such subjects in the present 3-year study.

Adult↗

PubMed2006

Bone tissue formation adjacent to implants placed in fresh extraction sockets: an experimental study in dogs.

OBJECTIVE: To study the healing of marginal defects that occurred at implants placed in a healed ridge or in fresh extraction sockets. MATERIAL AND METHODS: Six dogs were used. The right side of the mandible was used in the first part of the study. The first, second premolars and first molars were extracted. After 3 months of healing the bone was prepared for implant installation in these premolar and molar sites. The marginal 5 mm of each recipient site was widened with a conical drill. Following implant installation a gap of varying dimension occurred around the titanium rod (artificial defect (A) sites). At this interval the third and fourth premolars were extracted and implants were installed in the distal socket of the two teeth (natural defect (N) sites). The flaps were sutured to allow non-submerged healing. After 2 months, the procedures were repeated in the left side. Two months later the animals were euthanized, and biopsies were obtained and prepared for histological examination. RESULTS: The length of the zone of de novo'bone-to-implant contact' in the defect region was longer at the A sites than at the N sites both at the 2- and the 4-month interval. Further, while after 4 months of healing the marginal bone crest at the A sites was located close to the abutment/fixture junction, at the N sites a marked reduction of the height of the bone crest was documented. Hence, most A site defects became completely resolved whereas healing of the N site defects was incomplete. CONCLUSION: The process of bone modeling and remodeling at an implant placed in a fresh extraction socket differs from the resolution of marginal defects that may occur following implant installation in a healed ridge.

Animals↗

PubMed2006

Modeling of the buccal and lingual bone walls of fresh extraction sites following implant installation.

OBJECTIVE: To determine whether the reduction of the alveolar ridge that occurs following tooth extraction and implant placement is influenced by the size of the hard tissue walls of the socket. MATERIAL AND METHODS: Six beagle dogs were used. The third premolar and first molar in both quadrants of the mandible were used. Mucoperiostal flaps were elevated and the distal roots were removed. Implants were installed in the fresh extraction socket in one side of the mandible. The flaps were replaced to allow a semi-submerged healing. The procedure was repeated in the contra later side of the mandible after 2 months. The animals were sacrificed 1 month after the final implant installation. The mandibles were dissected, and each implant site was removed and processed for ground sectioning. RESULTS: Marked hard tissue alterations occurred during healing following tooth extraction and implant installation in the socket. The marginal gap that was present between the implant and the walls of the socket at implantation disappeared as a result of bone fill and resorption of the bone crest. The modeling in the marginal defect region was accompanied by marked attenuation of the dimensions of both the delicate buccal and the wider lingual bone wall. Bone loss at molar sites was more pronounced than at the premolar locations. CONCLUSION: Implant placement failed to preserve the hard tissue dimension of the ridge following tooth extraction. The buccal as well as the lingual bone walls were resorbed. At the buccal aspect, this resulted in some marginal loss of osseointegration.

Alveolar Bone Loss↗

PubMed2006

Tissue modeling following implant placement in fresh extraction sockets.

OBJECTIVE: To study whether osseointegration once established following implant placement in a fresh extraction socket may be lost as a result of tissue modeling. MATERIAL AND METHODS: Seven beagle dogs were used. The third and fourth premolars in both quadrants of the mandible were used as experimental teeth. Buccal and lingual full-thickness flaps were elevated and distal roots were removed. Implants were installed in the fresh extraction socket. Semi-submerged healing of the implant sites was allowed. In five dogs, the experimental procedure was first performed in the right side of the mandible and 2 months later in the left mandible. These five animals were sacrificed 1 month after the final implant installation. In two dogs, the premolar sites on both sides of the mandible were treated in one surgical session and biopsies were obtained immediately after implant placement. All biopsies were processed for ground sectioning and stained. RESULTS: The void that existed between the implant and the socket walls at surgery was filled at 4 weeks with woven bone that made contact with the SLA surface. In this interval, (i) the buccal and lingual bone walls underwent marked surface resorption and (ii) the height of the thin buccal hard tissue wall was reduced. The process of healing continued, and the buccal bone crest shifted further in the apical direction. After 12 weeks, the buccal crest was located>2 mm apical of the marginal border of the SLA surface. CONCLUSION: The bone-to-implant contact that was established during the early phase of socket healing following implant installation was in part lost when the buccal bone wall underwent continued resorption.

Animals↗

PubMed2005

Dimensional ridge alterations following tooth extraction. An experimental study in the dog.

OBJECTIVE: To study dimensional alterations of the alveolar ridge that occurred following tooth extraction as well as processes of bone modelling and remodelling associated with such change. MATERIAL AND METHODS: Twelve mongrel dogs were included in the study. In both quadrants of the mandible incisions were made in the crevice region of the 3rd and 4th premolars. Minute buccal and lingual full thickness flaps were elevated. The four premolars were hemi-sected. The distal roots were removed. The extraction sites were covered with the mobilized gingival tissue. The extractions of the roots and the sacrifice of the dogs were staggered in such a manner that all dogs contributed with sockets representing 1, 2, 4 and 8 weeks of healing. The animals were sacrificed and tissue blocks containing the extraction socket were dissected, decalcified in EDTA, embedded in paraffin and cut in the buccal-lingual plane. The sections were stained in haematoxyline-eosine and examined in the microscope. RESULTS: It was demonstrated that marked dimensional alterations occurred during the first 8 weeks following the extraction of mandibular premolars. Thus, in this interval there was a marked osteoclastic activity resulting in resorption of the crestal region of both the buccal and the lingual bone wall. The reduction of the height of the walls was more pronounced at the buccal than at the lingual aspect of the extraction socket. The height reduction was accompanied by a "horizontal" bone loss that was caused by osteoclasts present in lacunae on the surface of both the buccal and the lingual bone wall. CONCLUSIONS: The resorption of the buccal/lingual walls of the extraction site occurred in two overlapping phases. During phase 1, the bundle bone was resorbed and replaced with woven bone. Since the crest of the buccal bone wall was comprised solely of bundle this modelling resulted in substantial vertical reduction of the buccal crest. Phase 2 included resorption that occurred from the outer surfaces of both bone walls. The reason for this additional bone loss is presently not understood.

Alveolar Bone Loss↗

PubMed2005

The effect of systemic administration of ibuprofen in the experimental gingivitis model.

BACKGROUND: Studies in humans have indicated that systemically administered flurbiprofen and ibuprofen may reduce gingivitis. De novo plaque formation is enhanced at tooth surfaces adjacent to inflamed gingivae. OBJECTIVE: The aim of the present clinical trial was to evaluate the effect of systemic administration of ibuprofen on gingivitis and plaque build-up. MATERIAL AND METHODS: Eleven subjects were recruited for the study and were given oral hygiene instruction, scaling and professional mechanical tooth cleaning (PTC). At the end of a preparatory period (Day 0), the participants were told to abstain from all mechanical plaque control measures during a 2-week experimental period but to rinse with an assigned mouth rinse (positive control: 0.1% chlorhexidine digluconate; negative control: saline) or administer ibuprofen (tablets of 200 mg twice daily). Mouth rinsing was performed twice a day (after breakfast and in the evening), for 60 s with 10 ml. Re-examination was performed after 14 days of experiment. After a 2-week "wash-out" period, the participants received a new PTC and a second 14-day experimental period was initiated. The experimental and "wash-out" periods were repeated until all volunteers had been involved in all three regimens. Dental plaque was scored using the Quigley & Hein Plaque Index system and gingivitis according to the Gingival Index (GI) system. Supragingival plaque was collected and prepared for dark-field microscopy. One hundred bacterial cells were counted and classified into six different groups: coccoid cells, straight rods, filaments, fusiforms, spirochetes and motile rods. Gingival crevicular fluid (GCF) was collected from the same sites that were sampled for plaque. The volume of GCF collected in each strip was measured and analysed regarding content of lactoferrin and albumin. RESULTS: During the period when the panelists rinsed with saline they accumulated large amounts of plaque and developed marked signs of gingivitis. When they rinsed with chlorhexidine digluconate, small amounts of plaque formed and few sites received GI score > or =2. After the 2 weeks of ibuprofen administration, the panelists presented with significantly fewer sites that scored GI > or =2 but had formed similar amounts of plaque as during the negative control period. CONCLUSION: It is suggested that ibuprofen administered via the systemic route has an effect on gingivitis but not on de novo plaque formation.

Administration, Oral↗

PubMed2005

Bone regeneration at implants with turned or rough surfaces in self-contained defects. An experimental study in the dog.

BACKGROUND: Marginal hard tissue defects present at implants with a rough surface can heal with a high degree of bone fill and osseointegration. The healing of similar defects adjacent to implants with a smooth surface appears to be less predictable. OBJECTIVE: The aim was to compare bone healing at implants with turned or rough surface topographies placed in self-contained defects using either a submerged or non-submerged installation technique. MATERIAL AND METHODS: Six dogs were used. Three months after tooth extraction four experimental sites were prepared for implant installation in both sides of the mandible. The marginal 5 mm of the canal prepared for the implant was widened. Thus, following implant placement a circumferential gap occurred between the bone tissue and the implant surface that was between 1 and 1.25 mm wide. In each side of the mandible two implants with a turned surface and two implants with a rough surface were installed. The implants in the right side were fully submerged, while a non-submerged technique was applied in the left side. The animals were sacrificed 4 months later, block biopsies of each implant site were dissected and ground as well as paraffin sections were prepared. RESULTS: The marginal defects around rough surface implants exhibited after 4 months of healing substantial bone fill and a high degree of osseointegration following either the submerged or the non-submerged installation technique. Healing at turned implants was characterized by incomplete bone fill and the presence of a connective tissue zone between the implant and the newly formed bone. The distance between the implant margin (M) and the most coronal level of bone-to-implant contact (B) at implants with a rough surface was 0.84+/-0.37 mm at submerged and 0.90+/-0.39 mm at non-submerged sites. The distance M-B at implants with a turned surface was 3.39+/-0.52 mm at submerged and 3.23+/-0.68 mm at non-submerged sites. The differences between the rough and turned implants regarding the length of distance M-B were statistically significant (paired t-test). CONCLUSION: Osseointegration at implants placed in sites with marginal defects is influenced by the surface characteristics of the implant.

Alveolar Bone Loss↗

PubMed2005

Implant-supported single-tooth restorations: a 5-year prospective study.

BACKGROUND: Comparatively few studies are available reporting at least 5 years of follow-up data of implant-supported single-tooth replacements. OBJECTIVE: To evaluate prospectively the 5-year outcome of implant-supported single-tooth prosthetic restorations. MATERIAL AND METHODS: Forty subjects (mean age 41 years), 23 males and 17 females, who required single-tooth prosthetic replacement for a missing tooth were recruited. A total of 45 self-tapping implants (Astra Tech ST-implants)--40 in the maxilla and five in the mandible--were installed in a two-stage procedure. Abutment connection was performed 3-6 months after implant installation. Clinical and radiographic examinations were performed at the completion of the prosthetic treatment and once a year during a 5-year follow-up period. The analysis of peri-implant bone level alteration was performed on subject and implant levels and by the use of analysis of variance and binary logistic regression. RESULTS: Three patients were lost during the 5 years of follow-up. One implant was lost after 2.5 years in function and another four implants could not be accounted for at the 5-year follow-up examination. The overall failure rate at 5 years was 2.6% (subject level) and 2.3% (implant level). The mean loss of marginal bone at the implants during the first year in function was 0.06 mm (SD 0.67) on the subject level and 0.02 mm (0.65) on the implant level. During the subsequent 4 years the annual change in peri-implant bone level amounted to -0.02 mm (0.22) on both subject and implant levels. Thus, the mean total bone level change over the 5-year interval was -0.14 mm (1.04) on subject level and -0.11 mm (1.00) on the implant level of analysis (p>0.05). The frequency of implants with a 5-year bone loss of > or =1 mm was 13%. Approximately 50% of the implants demonstrated no bone loss. CONCLUSION: The present clinical trial on single-tooth replacements with the Astra Tech implant system demonstrated that the bone loss during the first year of function as well as annually thereafter was small.

Adult↗

PubMed2005

Ridge alterations following implant placement in fresh extraction sockets: an experimental study in the dog.

OBJECTIVE: To study dimensional alterations of the alveolar ridge that occurred following implant placement in fresh extraction sockets. MATERIAL AND METHODS: Five beagle dogs were included in the study. In both quadrants of the mandible, incisions were made in the crevice region of the third and fourth pre-molars. Buccal and minute lingual full-thickness flaps were elevated. The mesial root of the four pre-molars root was filled and the teeth were hemi-sected. Following flap elevation in (3)P(3) and (4)P(4) regions, the distal roots were removed. In the right jaw quadrants, implants with a sand blasted and acid etched (SLA) surface were placed in the fresh extraction sockets, while in the left jaws the corresponding sockets were left for spontaneous healing. The mesial roots were retained as surgical control teeth. After 3 months, the animals were examined clinically, sacrificed and tissue blocks containing the implant sites, the adjacent tooth sites (mesial root) and the edentulous socket sites were dissected, prepared for ground sectioning and examined in the microscope. RESULTS: At implant sites, the level of bone-to-implant contact (BC) was located 2.6+/-0.4 mm (buccal aspect) and 0.2+/-0.5 mm (lingual aspect) apical of the SLA level. At the edentulous sites, the mean vertical distance (V) between the marginal termination of the buccal and lingual bone walls was 2.2+/-0.9 mm. At the surgically treated tooth sites, the mean amount of attachment loss was 0.5+/-0.5 mm (buccal) and 0.2+/-0.3 mm (lingual). CONCLUSIONS: Marked dimensional alterations had occurred in the edentulous ridge after 3 months of healing following the extraction of the distal root of mandibular pre-molars. The placement of an implant in the fresh extraction site obviously failed to prevent the re-modelling that occurred in the walls of the socket. The resulting height of the buccal and lingual walls at 3 months was similar at implants and edentulous sites and vertical bone loss was more pronounced at the buccal than at the lingual aspect of the ridge. It is suggested that the resorption of the socket walls that occurs following tooth removal must be considered in conjunction with implant placement in fresh extraction sockets.

Alveolar Process↗

PubMed2005

Methyl cellulose gel obstructed bone formation by GBR: an experimental study in rats.

AIM: To evaluate whether bone formation under Teflon capsules may be enhanced by concomitant implantation of recombinant human platelet-derived growth factor-BB/insulin-like growth factor-I (rhPDGF-BB/IGF-I) incorporated into a methyl cellulose gel. MATERIALS AND METHODS: Fifty-five male 6-month-old albino rats of the Wistar strain were used in the study. The lateral aspect of the mandibular ramus was exposed on both sides of the jaw. In 70 sites, the periosteum was removed from the ramus, leaving the bone denuded, while in 35 sites, it was preserved. On 10 non-periosteal (P-) sites and five periosteal (P+) sites, an empty rigid teflon capsule (d=7 mm), serving as control, was placed on the ramus. In the 40 test animals, the capsule placed on the one side of the jaw was filled at random with one of three different concentrations (1,200, 600, 150 microg/ml) of rhPDGF-BB/IGF-I gel. The capsules placed on the contralateral side of the jaw contained a placebo methyl cellulose gel. Each growth factor group, defined according to the gel concentration, and the placebo group contained 10 capsules placed on the P- side and five capsules placed on the P+ side. Two months after surgery, all animals were sacrificed. RESULTS: Histologic analysis revealed that in the non-filled control capsules, the amount of new bone including the bone marrow was 29.9% and 39.7% of the capsule area on the P- and P+ sides, respectively. In the test capsules with the growth factor gel and placed on the P-sides, the amounts of new bone ranged from 5.6% to 6.3%, which were similar (p>0.05) to that formed in the capsules filled with the methyl cellulose gel (5.5%). New bone formation was larger in the capsules on the P+ sides than in those on the P- sides but was similar in the capsules with different growth factor concentrations (range 17.9-19.6%) and in those with placebo gel (21.0%). In all groups, the carrier gel was poorly absorbed and occupied most of the capsules. CONCLUSION: Local application of a methyl cellulose gel obstructed bone formation under Teflon capsules placed adjacent to uninjured cortical bone in the mandibular ramus of rats. These data suggest that another material should be utilized to deliver growth factors under Teflon membranes for guided bone regeneration.

Animals↗

PubMed2005

Implant stability during initiation and resolution of experimental periimplantitis: an experimental study in the dog.

BACKGROUND: Histologic studies have demonstrated the possibility to reestablish direct bone-implant contacts after ligature-induced periimplantitis. The influence of the reosseointegration on the stability of implants is not known. PURPOSE: The aim of the present investigation was to study bone tissue and associated implant stability alterations that occurred during induction and resolution of periimplantitis using resonance frequency analysis (RFA), radiography, and histology. MATERIALS AND METHODS: Three implants with smooth (turned) or roughened (SLA) surfaces were placed in each side of the edentulous mandible of four dogs. Experimental periimplantitis was induced for 3 months. Five weeks later, the animals were treated with antibiotics and surgical therapy and were followed for another 6 months. Periapical radiographs and RFA were used to evaluate marginal bone levels and implant stability throughout the study period. After termination, the tissue-implant interface was evaluated by light microscopy in ground sections. RESULTS: There was a linear relationship between radiographic and RFA findings because continuous loss of marginal bone and a decrease in implant stability were observed for both implant surfaces during the periimplantitis period. Antibiotic treatment and surgical therapy resulted in some reosseointegration, which was more marked for the SLA surface. The resonance frequency values corresponded well to the histometric measurements because reosseointegration resulted in an increase in implant stability. CONCLUSIONS: The findings from the present study indicate a linear relationship between marginal bone level and resonance frequency value. It is suggested that the RFA technique is sensitive and may be used to detect even a minor change in the level of bone-implant contact.

Alveolar Bone Loss↗

PubMed2004

The influence of a biomaterial on the closure of a marginal hard tissue defect adjacent to implants. An experimental study in the dog.

OBJECTIVES: The present experiment was performed to determine the influence of Bio-Oss on hard tissue formation at sites that, following implant installation, presented a 1-1.25 mm wide marginal defect. MATERIAL AND METHODS: Four Labrador dogs were used. The premolars and first molars on both sides of the mandible were extracted. After 3 months, mucoperiosteal flaps were elevated and three experimental sites were prepared for implant installation in each side of the mandible. A step drill was used to widen the marginal 5 mm of the canal. Thus, following the placement of the implant (3.3 x 10 mm, SLA surface, Straumann AG, Waldenburg, Switzerland) a circumferential gap, about 1-1.25 wide and 5 mm deep, remained lateral to the titanium rod. The test sites in the left side of the mandible were first filled with a deproteinized cancellous bone mineral (Bio-Oss). The defect sites in the right side of the mandible (control sites) were left for spontaneous healing. A resorbable barrier membrane (Bio-Gide) was placed to cover the implant and the bone tissue in two sites of each quadrant, while the third site was left without membrane placement. The flaps were repositioned to cover all defect sites and were sutured. After 4 months of healing, block biopsies of each implant site were dissected and processed for ground sectioning. RESULTS: It was demonstrated that at 4 months, all types of defects were filled with newly formed bone and that the biomaterial placed in the marginal defect in conjunction with implant installation during healing became incorporated in the newly formed bone tissue. A high degree of contact was established between the Bio-Oss particles and the newly formed bone. CONCLUSION: Bio-Oss became integrated with the newly formed bone. In the model used, Bio-Oss did not enhance the process of bone formation and defect closure.

Absorbable Implants↗

PubMed2004

Some characteristics of 50/55-year-old individuals with various experience of destructive periodontal disease: a cross-sectional study.

OBJECTIVE: To analyze the association between subject characteristics and degree of destructive periodontal disease in a randomly selected sample of 50/55-year-old individuals. METHODS: A randomized and geographically stratified (urban/rural districts) subject sample composed of dentate 50-year-old (n = 190) and 55-year-old individuals (n = 359) from the county of Varmland, Sweden were examined. Data were collected through full mouth clinical and radiographic examinations and by the use of questionnaires. Based on the cumulative distribution of the individuals with respect to mean probing attachment loss (PAL), subgroups of subjects with the lowest (L20%) and highest (H20%) experience of PAL were identified. Similar classifications were made for never-smokers and current smokers. Correlation analyses and forward stepwise logistic regression models were performed. RESULTS: The subgroup with the most extensive PAL loss (H20%) included a significantly higher proportion of (i) males (60 vs 33%), (ii) subjects with low educational level (65 vs 41%), (iii) smokers (49 vs 15%), and had (iv) less favorable lifestyle characteristics than the subgroup with minimal experience of PAL loss (L20%). The same pattern of differences was observed when the analysis was restricted to never-smokers, with the addition of a significantly lower proportion of subjects living in urban areas (40 vs 69%) in the H20% compared to the L20% subgroup. The stepwise logistic regression analysis revealed that number of teeth and smoking habits were significant factors in the identification of individuals in the L20% subgroup. For the H20% subgroup, number of teeth, gender, number of cigarettes/day and lifestyle index were significant explanatory variables. CONCLUSION: Number of remaining teeth and smoking habits were identified as the main discriminating factors for classification of subjects with regard to degree of destructive periodontal disease.

Analysis of Variance↗

PubMed2004

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 Varmland, 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 > or =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 > or =6 mm" and "smoking".

Alveolar Bone Loss↗

PubMed2004

Early bone formation adjacent to rough and turned endosseous implant surfaces. An experimental study in the dog.

OBJECTIVE: To validate a proposed model (Berglundh et al. 2003) and to evaluate the rate and degree of osseointegration at turned (T) and sand blasted and acid etched (SLA) implant surfaces during early phases of healing. MATERIAL AND METHODS: The devices used for the study of early healing had a geometry that corresponded to that of a solid screw implant with either a SLA or a T surface configuration. A circumferential trough had been prepared within the thread region (intra-osseous portion) that established a geometrically well-defined wound chamber. Twenty Labrador dogs received totally 160 experimental devices to allow the evaluation of healing between 2 h and 12 weeks. Both ground and decalcified sections were prepared from mesial/distal and buccal/lingual device sites. Histometric and morphometric analyses of the ground sections and morphometric analysis of the tissue components in decalcified sections were performed. RESULTS: The ground sections provided an overview of the various phases of tissue formation, while the decalcified, thin sections enabled a more detailed study of events involved in bone tissue modeling and remodeling for both SLA and T surfaces. The initially empty wound chamber became occupied with a coagulum and a granulation tissue that was replaced by a provisional matrix. The process of bone formation started already during the first week. The newly formed bone present at the lateral border of the cut bony bed appeared to be continuous with the parent bone, but on the SLA surface woven bone was also found at a distance from the parent bone. Parallel-fibered and/or lamellar bone as well as bone marrow replaced this primary bone after 4 weeks. In the SLA chambers, more bone-to-device contact, more initial woven bone and earlier lamellar bone formation was found than in the T chambers. CONCLUSION: Osseointegration represents a dynamic process both during its establishment and its maintenance. While healing showed similar characteristics with resorptive and appositional events for both SLA and T surfaces, the rate and degree of osseointegration were superior for the SLA compared with the T chambers.

Animals↗

PubMed2004

Histopathological observations of human periimplantitis lesions.

OBJECTIVE: The aim of the present study was to analyze some characteristics of advanced and progressive periimplantitis lesions in man. MATERIAL AND METHODS: Soft tissue biopsies were obtained from 12 implants in six patients. The implants had been in function between 4 and 21 years and were, with one exception, located in the maxilla. The radiographic examination performed prior to biopsy revealed that all sites exhibited advanced bone loss. Further, clinical signs of severe inflammation, such as suppuration, swelling and/or fistula formation were detected in the majority of sites and seven of the 12 implants were found to be mobile at biopsy. Each biopsy was following fixation embedded in epoxy resin and sections were prepared for histometric and morphometric analysis. RESULTS AND CONCLUSION: It was demonstrated (i). that all soft tissue units harbored large inflammatory cell infiltrates (ICT) that extended to a position apical of a pocket epithelium and (ii). that about 60% of the lesions were occupied by inflammatory cells, among which plasma cells dominated. Numerous amounts of PMN cells occurred not only in the pocket epithelium and adjacent connective tissue areas, but were also present in peri-vascular compartments in more central areas of the ICT.

Aged↗

PubMed2004

Resolution of bone defects of varying dimension and configuration in the marginal portion of the peri-implant bone. An experimental study in the dog.

BACKGROUND: It was demonstrated that a marginal defect of about 1 mm between the bone wall and the metal surface after implant installation can heal with a high degree of bone fill and osseointegration. OBJECTIVE: The aim of the present animal experiment was to study bone healing at implant sites with hard tissue defects of varying dimensions and configuration. MATERIAL AND METHODS: Four Labrador dogs were used. All mandibular premolars and first molars were extracted. After 3 months of healing, five experimental sites, two control (C1, C2) and three test (T1, T2, T3) sites, were identified. In all five sites, custom-made implants with a sand-blasted, large-grit, acid-etched (SLA) surface and with an outer dimension of 3.3x10 mm, were used. In site C1, traditional implant installation was performed. In site C2, the marginal 5 mm of the canal, prepared for the implant, was widened to 5.3 mm using a step-drill. Thus, following the installation of the implant, a circumferential gap occurred between the bone tissue and the metal rod that was 5 mm deep and between 1 and 1.25 mm wide. In test site T1, the canal was widened to establish a marginal gap of 2-2.25 mm. In test sites T2 and T3, the marginal 5 mm of the canal was first widened to 5.3 mm (T2) or 7.3 mm (T3). The buccal bone wall opposite the defect was subsequently removed. Following the placement of a cover screw in sites C2, T1, T2, and T3, a resorbable membrane was placed over the defect. All implants were submerged. After 4 months of healing, block biopsies of each implant site were dissected and processed for ground sectioning. RESULTS: The observations disclosed that four-wall defects of different dimensions (1-2.25 mm wide) that occurred in the marginal portion of the recipient sites following implant installation were resolved during healing. Further, at sites where the buccal bone wall during defect preparation was intentionally removed, healing resulted in defect resolution at the mesial, distal, and lingual aspects. At the buccal aspects, healing was incomplete but the dimension of the defect was reduced by the limited amounts of new bone formation extending from the lateral and apical borders of the defect. CONCLUSION: Wide marginal defects may during healing be filled with bone. In such defects a high degree of osseointegration may occur to implants designed with an SLA surface.

Absorbable Implants↗