Occurrence of complications in patients restored with implants.

OBJECTIVES: To determine the occurrence and clustering of complications in subjects restored with fixed implant-supported prostheses. METHODS: In the present retrospective case series, 241 subjects treated at one clinical centre and provided with 729 implants were included. A clinical and radiographic examination was performed after a mean follow-up period of 4.8 ± 2.0 years. Additional information on occurrence of technical (chipping, loss of retention, fracture of components) and biological complications (marginal bone loss, implant loss) during follow-up was extracted from patient records. For each type of complication and complications overall, regression analyses were performed to identify potential risk factors. Cox regression analyses were used to evaluate time to event for implant loss and technical complications. RESULTS: In all, 30% of the 241 patients presented with at least one complication of technical and/or biological character during the follow-up period. Technical complications affected 19.5% of subjects, while 14.1% presented with marginal bone loss >2 mm. Implant loss occurred in 4.6% of subjects. While technical complications were noted already early during the maintenance period (<1200 days), implant loss typically occurred during a later phase. A small subgroup of subjects (7.9%) experienced more than one type of complication. CONCLUSIONS: Complications occurred frequently and the most common type of complication was of technical character. Technical and biological complications occurred independently of each other.

Peri-implant health.

OBJECTIVE: The aim is to define clinical and histologic characteristics of peri-implant tissues in health and describe the mucosa-implant interface. IMPORTANCE: An understanding of the characteristics of healthy peri-implant tissues facilitates the recognition of disease (i.e., departure from health). FINDINGS: The healthy peri-implant mucosa is, at the microscopic level, comprised of a core of connective tissue covered by either a keratinized (masticatory mucosa) or non-keratinized epithelium (lining mucosa). The peri-implant mucosa averages about 3 to 4 mm high, and presents with an epithelium (about 2 mm long) facing the implant surface. Small clusters of inflammatory cells are usually present in the connective tissue lateral to the barrier epithelium. Most of the intrabony part of the implant appears to be in contact with mineralized bone (about 60%), while the remaining portion faces bone marrow, vascular structures, or fibrous tissue. During healing following implant installation, bone modeling occurs that may result in some reduction of the marginal bone level. CONCLUSIONS: The characteristics of the peri-implant tissues in health are properly identified in the literature, including tissue dimensions and composition. Deviation from the features of health may be used by the clinician (and researcher) to identify disease, including peri-implant mucositis and peri-implantitis.

Long-term outcome of surgical treatment of peri-implantitis. A 2-11-year retrospective study.

OBJECTIVE: To assess long-term clinical and radiological outcomes of surgical treatment of peri-implantitis. MATERIAL AND METHODS: Files and radiographs from 50 patients who had received surgical treatment for peri-implantitis were analyzed. Data on clinical characteristics prior to surgical therapy and at latest follow-up were obtained. In each radiograph, the marginal bone level was assessed at the mesial and distal aspects of the affected implants. The treatment included oral hygiene instruction, professional supra-mucosal instrumentation, and surgical therapy aiming at pocket elimination. Following flap elevation and removal of inflamed tissue, the affected implant was cleaned using gauze soaked in saline. Calculus was removed. When indicated, osseous re-contouring was carried out to facilitate pocket elimination. Flaps were adjusted, sutured, and compressed to the crestal bone. Supportive therapy including oral hygiene control was provided with 4-month intervals. RESULTS: Treatment was effective in resolving the inflammatory condition as documented by marked reduction in peri-implant probing depth and bleeding on probing scores together with crestal bone level preservation. Treatment outcome was significantly better at implants with non-modified surfaces than at implants with modified surfaces. The probability of an implant to exhibit no further bone loss or bone gain after treatment was high if the peri-implant mucosa at the site presented with shallow pockets and the absence of bleeding on probing at follow-up. CONCLUSIONS: The results of the study revealed that (i) surgical treatment of peri-implantitis was effective in the long-term, (ii) outcome was better at implants with non-modified than with modified surfaces, and (iii) preservation of crestal bone support was consistent with healthy peri-implant tissue conditions.

Bone loss at implants and teeth in the same inter-proximal unit: A radiographic study.

OBJECTIVE: This study was performed to determine whether the distance between an implant and a tooth present in an inter-proximal unit influenced the amount of marginal bone loss that occurred at the two facing (adjacent) surfaces. MATERIALS AND METHODS: One hundred and eighty patients with a total of 278 inter-proximal units were included. Radiographs of implants that also included adjacent (facing) natural tooth/teeth were digitalized, and various linear measurements were performed using a software program. The marginal bone level and the bone level change that had occurred during a mean of 5.8 years were assessed as well as distance between the implant and the adjacent tooth/teeth. RESULTS: The mean amount of additional marginal bone loss that took place during the observation period was about 0.4 mm at both implants and adjacent tooth surfaces. The horizontal distance between an implant and the facing tooth did not influence the amount of marginal bone loss that had occurred. In most inter-proximal units, more advanced bone loss (>1 mm, >2 mm) had ensued either at the implant or at the facing tooth surface. Advanced additional bone loss occurred at both the implant and the tooth in only about 3% of the examined subjects. CONCLUSION: Bone loss at implants and teeth appears to be a site-specific phenomenon and not dependent on the inter-proximal distance.

Marginal bone loss at implants with different surface characteristics - A 20-year follow-up of a randomized controlled clinical trial.

OBJECTIVE: This report is a 20-year follow-up of a randomized controlled clinical trial evaluating the potential long-term effect of a modified implant surface on the preservation of the peri-implant marginal bone level. MATERIAL & METHODS: In each of 51 patients and for each fixed partial denture (FPD), by randomization at least one implant installed had a non-modified turned surface and one a modified and roughened surface (TiOblast® ). Clinical and radiological examinations were performed at various follow-up intervals. Primary outcome variables were peri-implant marginal bone level change from time of loading and proportion of implants with no bone loss at 20 years. Multilevel analysis followed by nonparametric and Pearson's Chi-Square tests were applied for statistical analysis. RESULTS: At the 20-year follow-up, 25 patients carrying 64 implants were available for evaluation. Turned and TiOblast implants presented with a mean bone level change from the time of FDP delivery amounting to -0.41 mm (95% CI -0.84/0.02) and -0.83 mm (95% CI -1.38/-0.28) respectively (inter-group comparison p > .05). 47% of the Turned and 34% TiOblast implants (p > .05) showed no bone loss. All but one of these implants were free of bacterial plaque and inflammation as well as presented with probing pocket depths ≤5 mm at both the 5- and 20-year follow-up examinations. CONCLUSION: It is suggested that a moderate increase of implant surface roughness has no beneficial effect on long-term preservation of the peri-implant marginal bone level.

Effect of socket grafting with deproteinized bone mineral: An RCT on dimensional alterations after 6 months.

OBJECTIVE: To examine if (i) characteristics of the fresh extraction socket site influenced subsequent dimensional alterations and (ii) placement of deproteinized bovine mineral in the socket affected volumetric change during healing. MATERIALS AND METHODS: Twenty seven subjects and 28 extraction sites were included. Immediately after the removal of the tooth and after 6 months of healing, stone and virtual models of the jaw were produced. A cone beam computerized tomography scan was obtained immediately after extraction and the thickness of the buccal bone wall at the extraction site was measured. Extraction sites were randomly assigned to test or control group. In the test group, extraction sockets were filled with deproteinized bone mineral and covered with a collagen membrane. In the control group, only a collagen membrane was placed. RESULTS: The thickness of the buccal bone wall at the extraction site influenced the amount of volume reduction that occurred. Socket grafting influenced the degree of ridge diminution only at sites where the buccal bone wall was thin (≤ 1 mm). CONCLUSION: A graft comprised of collagen-enriched deproteinized bovine bone mineral, placed to fill extraction sockets failed to influence the overall diminution of the ridge that occurred during healing. The thickness of the buccal bone wall apparently had a significant influence on volumetric alterations of the edentulous ridge following tooth extraction.

Bone loss at implants and teeth in the same segment of the dentition in partially dentate subjects.

BACKGROUND: Some studies have indicated that marginal bone loss at implants and at teeth are similar, while results from other studies showed that implants lost more bone than teeth in the same dentition. AIM: To determine the amount of progressive marginal bone loss that had occurred at implants and teeth in the same segment of the dentition following implant placement in partially dentate subjects. MATERIAL AND METHODS: A total of 217 patients with a total of 573 implants and 318 teeth present in the same segments of the dentition were included. Radiographs were available from 1 year (baseline) and ≥3 years after loading. RESULTS: The mean bone loss that occurred between the two examinations was at implants 0.42 ± 0.68 mm and at teeth 0.44 ± 0.52 mm. Thirty-eight subjects (18%) had ≥1 implant exhibiting >1 mm bone loss. Bone loss at the 148 implants in this category of patients was 1.30 ± 1.04 mm with a corresponding loss at the 69 teeth of 0.53 ± 0.62 mm. Eighteen subjects (8%) had ≥1 tooth that exhibited >1 mm bone loss. The mean amount of bone loss in this sample was 1.37 ± 0.87 mm (38 teeth) and 0.29 ± 0.31 mm (56 implants). CONCLUSIONS: This study showed that marginal bone loss at implants and teeth in many partially dentate subjects might be independent phenomena.

The effect of placing a bone replacement graft in the gap at immediately placed implants: a randomized clinical trial.

OBJECTIVE: To assess the added value of using a bone replacement graft in combination with immediate implants in reducing the bone dimensional changes occurring in the residual ridge. MATERIAL AND METHODS: Randomized parallel controlled clinical trial to study the efficacy of grafting with demineralized bovine bone mineral with 10% collagen (DBBM-C) in the gap between the implant surface and the inner bone walls when the implants were immediately placed in the anterior maxilla. The changes between implant placement and 16 weeks later in the horizontal and vertical crestal bone changes in relation to the implant were evaluated through direct bone measurements using a periodontal probe. Mean changes were compared between the experimental and control sites using parametric statistics. RESULTS: A total of 86 implant sites in 86 subjects were included in the analysis (43 in the test group and 43 in the control group). The horizontal crest dimension underwent marked changes during healing mainly at the buccal aspect of the alveolar crest where this reduction amounted to 1.1 (29%) in the test group and 1.6 mm (38%) in the control group, being these statistically significant (P = 0.02). This outcome was even more pronounced at sites in the anterior maxilla and with thinner buccal bone plates. CONCLUSIONS: In conclusion, the results from this clinical trial demonstrated that placing a DBBM-C bone replacement graft significantly reduced the horizontal bone resorptive changes occurring in the buccal bone after the immediate implantation in fresh extraction sockets.

The alveolar process following single-tooth extraction: a study of maxillary incisor and premolar sites in man.

OBJECTIVE: The present investigation was performed to determine some dimensional alterations that occur in the alveolar process of the incisor and premolar sites of the maxilla following tooth removal. MATERIAL AND METHODS: Computer-assisted cone-beam computed tomography (CBCT) scans were obtained from the maxilla using an iCAT unit, and involved edentulous and contralateral tooth sites. For each site included in the study, parasagittal and axial reconstructions, 1 mm apart, were made and measurements of different variables (cross-sectional area, height, and width) performed. RESULTS: The study involved 69 subjects and disclosed that the cross-sectional area and the height and width of the alveolar process of the lateral incisor site were the smallest and those of the second premolar the largest. All parameters had been significantly reduced after the completion of the ≥1 year of healing. Thus, the overall (i) cross-sectional area was reduced from 99.1 to 65.0 mm(2) , (ii) the height from 11.5 to 9.5 mm, and (iii) the width from 8.5 to 3.2 mm (marginal 1/3(rd) ), 8.9 to 4.8 mm (middle portion), and 9.0 to 5.7 mm (apical portion). CONCLUSION: The removal of single tooth caused marked hard tissue diminution. The loss of hard tissue was most pronounced in the buccal and marginal portions of the edentulous ridge that in most sites had acquired a triangular shape.

Implant-supported single-tooth restorations. A 12-year prospective study.

OBJECTIVE: The aim of this study was to evaluate prospectively the 12-year outcome of implant-supported single-tooth restorations. MATERIAL AND METHODS: Originally 45 self-tapping Astra Tech TiOblast® ST-implants were installed by a two-stage protocol in 40 subjects requiring single-tooth prosthetic replacement for a missing tooth. Clinical and radiologic examinations were performed at completion of the prosthetic treatment 4-7 months after implant installation surgery and after 5 and 12 years in function. RESULTS: At 12 years 31 patients and 35 implants were available for evaluation. The overall failure rate after 12 years was 10.3% on the subject level and 9.1% on the implant level. The mean bone loss amounted to 0.67 mm (SD 2.20) on a subject level and 0.47 mm (1.72) on an implant level. Three subjects (10%) and three implants (8.6%) were diagnosed with peri-implantitis. Five subjects had experienced technical complications; three incidences of loosening of the abutment retention screw during the first 5 years and two minor porcelain fracture of the crown (two patients) between 5- and 12-years of follow-up. CONCLUSION: The findings reported in this 12-year prospective case series suggest that the use of the Astra Tech dental implants may be a valid treatment alternative for single-tooth replacement prostheses.

Temporal sequence of hard and soft tissue healing around titanium dental implants.

The objective of the present review was to summarize the evidence available on the temporal sequence of hard and soft tissue healing around titanium dental implants in animal models and in humans. A search was undertaken to find animal and human studies reporting on the temporal dynamics of hard and soft tissue integration of titanium dental implants. Moreover, the influence of implant surface roughness and chemistry on the molecular mechanisms associated with osseointegration was also investigated. The findings indicated that the integration of titanium dental implants into hard and soft tissue represents the result of a complex cascade of biological events initiated by the surgical intervention. Implant placement into alveolar bone induces a cascade of healing events starting with clot formation and continuing with the maturation of bone in contact with the implant surface. From a genetic point of view, osseointegration is associated with a decrease in inflammation and an increase in osteogenesis-, angiogenesis- and neurogenesis-associated gene expression during the early stages of wound healing. The attachment and maturation of the soft tissue complex (i.e. epithelium and connective tissue) to implants becomes established 6-8 weeks following surgery. Based on the findings of the present review it can be concluded that improved understanding of the mechanisms associated with osseointegration will provide leads and targets for strategies aimed at enhancing the clinical performance of titanium dental implants.

Dimensions of the healthy gingiva and peri-implant mucosa.

OBJECTIVE: To determine the dimensions of the soft tissue cuff present at various aspects of teeth and to compare these dimensions to those of the mucosa surrounding single implants. MATERIAL AND METHODS: Fifty volunteers were recruited that were ≥25 years of age and exhibited no signs of (i) untreated caries; (ii) loss of periodontal tissue support in the incisor, canine, and premolar regions; (iii) systemic or local disease. Furthermore, among the 50 patients recruited (iV), 27 had one single implant in the maxilla with teeth present mesial and/or distal to the implant. Probing pocket depth (PPD) and transmucosal sounding depth (TS) were assessed by five experienced, carefully calibrated examiners and with the use of a periodontal probe at the proximal (mesial, distal) and flat (facial, buccal and palatal/lingual) surfaces of all teeth/implants. The width of the keratinized mucosa (KM) was also determined. RESULTS: It was demonstrated that (i) PPD and TS were greater at proximal than at flat surfaces at both tooth and implant sites. In addition, both PPD and TS were deeper at implant than at tooth sites. The TS values documented that the cuff of healthy soft tissue that surrounded a tooth varied between 2 mm at flat surfaces and 4 mm at proximal surfaces, while at implant sites, the mucosa at proximal as well as flat surfaces was 1-1.5 mm greater. CONCLUSION: The probing pocket depth (PPD) and the transmucosal sounding depth (TS) values were greater at proximal than at flat, that is, facial/palatal (lingual) surfaces at tooth sites and frequently also at implant sites. Furthermore, the PPD and the TS dimensions were greater at implant than at adjacent tooth sites.

Ridge alterations following grafting of fresh extraction sockets in man. A randomized clinical trial.

OBJECTIVE: To evaluate dimensional alterations of the alveolar ridge that occurred following tooth extraction at sites grafted with Bio-Oss(®) Collagen. MATERIAL AND METHODS: Twenty-eight subjects with maxillary incisors, canines, and premolars scheduled for extraction were included. The tooth was carefully removed. The patients were randomly assigned to a test or a control group. In the test group patients, Bio-Oss(®) Collagen was placed in the fresh extraction socket while in the controls no grafting was performed. Radiographic examination (cone beam computed tomograms, CBCT) was performed immediately after tooth extraction and socket treatment. Four months later, a new CBCT was obtained. In the radiographs, (i) the distance (mm) between base of the alveolar process (apex) and the buccal and palatal crests was determined, (ii) the outer profile of alveolar process of the experimental sites was outlined, and the cross section of the area (mm(2) ) determined. RESULTS: After 4 months of healing, the buccal and to a less extent also the palatal bone plate had become markedly reduced in height. The placement of a biomaterial in the socket failed to prevent resorption of the buccal and palatal bone walls. The cross-sectional area of the control ridge was reduced about 25% and of the test ridge with 3%. CONCLUSION: The placement of a xenograft in fresh extraction sockets markedly counteracted the reduction in the hard tissue component of the edentulous sites.

Mucosal inflammation and incidence of crestal bone loss among implant patients: a 10-year study.

OBJECTIVE: The objective of this prospective study was to determine the prevalence and incidence of marginal bone loss and, in addition, peri-implantitis in subjects and implant sites after 10 years in function. MATERIAL AND METHODS: One hundred and thirty-three subjects with a total of 407 implants that had been in function for about 5 years attended a follow-up visit in 2007 (visit 2; V2). 100 of the 133 subjects returned for a new clinical and radiographic examination in 2012 (visit 3; V3). The clinical examination included assessment of "bleeding on probing" (BoP+) and "probing pocket depth." Subjects with implant sites that in the radiograph exhibited crater-shaped marginal bone loss of >0.5 mm were identified as losers. RESULTS: During the interval between V2 and V3 (about 5 years), 13 implants in 7 subjects exhibited progressive bone loss and were removed. The overall amount of crestal bone loss that had occurred at the remaining implants between visit 1 (V1; ≥1 year of loading) and V3 (10 years) was small (0.36 ± 1.4 mm). The bone-level reduction was twice as great between V2 and V3 as between V1 and V2. Forty subjects and 75 (26%) implant sites exhibited marginal bone loss of >0.5 mm between V1 and V3. In the interval between V2 and V3, 37 new implant sites lost significant amounts of bone. During the entire 10-year period (V1-V3), 12% of patients and 5% of implants displayed signs of peri-implantitis (bone loss >0.5 mm, BoP+, PPD ≥6 mm), while in the V2-V3 interval, the corresponding numbers were 10% (patients) and 4% (implant sites). CONCLUSION: Sites with marginal bone loss of ≥1 mm were not common among implant patients. Peri-implantitis occurred in about 10% of patients and 4% of implant sites.

Ridge preservation with the use of deproteinized bovine bone mineral.

OBJECTIVE: The aim was to examine the tissue composition of extraction sockets that had been grafted with deproteinized bovine bone mineral and allowed to heal for 6 months. MATERIAL AND METHODS: Twenty-five subjects with one tooth each scheduled for extraction and replacement with dental implants were recruited. The assigned teeth were carefully removed. The site/patient was thereafter allocated to a test or a control group. In the test group patients, Bio-Oss(®) Collagen was placed to fill the fresh extraction socket while in the controls no grafting was performed. After about 6 months of healing, a biopsy was sampled from the center of the extraction site. The specimens were decalcified, embedded in paraffin, sectioned, and stained in HTX. The proportions occupied by mineralized bone, osteoid, bone marrow, fibrous tissue, and Bio-Oss(®) particles were determined by morphometric point counting. RESULTS: Mineralized bone made up 57.4 ± 12.4% of the control sites (C) and 48.9 ± 8.5% of the T1 sites (graft material not included). The amount of bone marrow (C: 7.1 ± 6.1%, T1: 2.1 ± 3.1%) and osteoid (C: 7.3 ± 4.9%, T1: 1.9 ± 2.1%) was about five times greater in the control than in the test sites. Fibrous tissue comprised 23.1 ± 16.3% (C) and 40.0 ± 11.9% (T1). I n the T2 sites (graft material included), the percentage mineralized bone was 39.9 ± 8.6 while the proportions of bone marrow and osteoid were 1.8 ± 2.5% and 1.6 ± 1.8%. Fibrous tissue occupied 32.4 ± 9.2% and Bio-Oss(®) particles 19.0 ± 6.5% of the T2 sites. CONCLUSION: Placement of the biomaterial in the fresh extraction socket retarded healing. The Bio-Oss(®) particles were not resorbed but became surrounded by new bone. This may explain why grafted extraction sites may fail to undergo dimensional change.

Implants placed in fresh extraction sockets in the maxilla: clinical and radiographic outcomes from a 3-year follow-up examination.

AIM: The aim of this prospective, randomized, controlled multicenter study was to determine the 3-year efficacy and stability of the soft and hard tissues at implants with a different geometry that were placed in fresh extraction sockets. MATERIAL AND METHODS: Implants with two different configurations, cylindrical (Group A) or conical/cylindrical (Group B) were installed, and healing abutments were attached. Sixteen weeks after implant placement, subjects returned for a re-entry procedure. Prosthetic restorations were delivered 22 weeks after implant placement. Each subject was placed in a 3-year follow-up program, including examinations at yearly visits including various soft tissue and bone level parameters. RESULTS: The percentage of sites that were considered inflamed during the follow-up period was stable and varied between 8.8% and 10.2%. The radiographic examinations documented improved bone levels at the final examination and the mean improvement from baseline (placement of permanent restoration; PR) amounted to 0.17 ± 0.67 mm. More than 70% (54 of 76) of the implants monitored in this study suffered no bone loss during the maintenance period. Moreover, there was an obvious "gain" of interproximal soft tissue volume and at the 3-year examination around 25% of all embrasure gaps were completely filled with "papillae". CONCLUSIONS: Both conical/cylindrical and cylindrical implants placed in fresh extraction sockets allowed proper soft and hard tissue healing to occur. At both types of implants, mucosal inflammation was infrequent, marginal bone levels were maintained, and soft tissue volume increased gradually after the placement of the permanent restoration.

Effect of periodontal therapy on the subgingival microbiota over a 2-year monitoring period. I. Overall effect and kinetics of change.

AIM: To examine the 2-year post-therapy kinetics of change in the composition of subgingival biofilms. MATERIAL AND METHODS: In this study, 178 chronic periodontitis subjects were recruited and clinically monitored at baseline, 3, 6, 12, 18 and 24 months after therapy. All subjects received scaling and root planing and 156 one or more of periodontal surgery, systemically administered amoxicillin + metronidazole or local tetracycline at pockets ≥5 mm. Subgingival biofilm samples taken from each subject at each time point were analysed for their content of 40 bacterial species using checkerboard DNA-DNA hybridization. The significance of changes in median species counts over time was sought using the Wilcoxon or Friedman tests and adjusted for multiple comparisons. RESULTS: Mean counts were significantly reduced from baseline to 2 years for 30 of the 40 taxa. Marked reductions were observed for periodontal pathogens including Tannerella forsythia, Treponema denticola and Eubacterium nodatum. The kinetics of change differed from species to species. When data were subset according to baseline PD, patterns of change in the microbial profiles were generally similar. CONCLUSION: Periodontal therapy leads to a rapid reduction in periodontal pathogens, followed by a slower reduction in other taxa that can be sustained for at least 2 years.

A cross-sectional study on the prevalence of marginal bone loss among implant patients.

OBJECTIVE: The aim of the present cross-sectional retrospective study was to determine bone loss in a sample of subjects restored with implant-supported prostheses and the prevalence and severity of peri-implantitis in a sub-sample. MATERIAL AND METHODS: A total of 139 patients who had attended a follow-up visit in 2007 were considered for inclusion. Subjects with implants that had been in function for less than 3 years or had poor quality radiographs were excluded. The final study population comprised 133 subjects with a total of 407 implants. Radiographic measurements identified subjects who had ≥1 implant site exhibiting marginal bone loss of >0.5 mm; 40 subjects met this criterion and were recalled for a clinical examination. Of the 40 subjects that were recalled for the clinical examination, 30 attended. The following parameters were recorded at mesial, distal, buccal, and lingual/palatal aspects of all implants: oral hygiene standard (plaque), bleeding on probing, probing pocket depth (PPD). RESULTS: The mean interval between the baseline (1-year post-loading) and the follow-up radiographs was 4.8 ± 2.3 years. In the total subject sample (133 subjects and 407 implants), the mean amount of marginal bone loss that had occurred was 0.2 ± 1.2 mm. Ninety-three subjects with 246 implant sites exhibited no bone level alteration (group A), whereas 40 subjects with 161 implant sites (group B) displayed marginal bone loss of >0.5 mm at ≥1 implant (loser site). Sixty-eight implant sites in group B exhibited bone loss of >0.5 mm. However, only 20% of subjects and 11% of sites had lost >1 mm marginal bone, and 8% of subjects and 4% of sites had lost >2 mm bone. The total amount of bone loss that had occurred in group B was (i) 0.88 ± 1.5 mm and (ii) among the loser sites 2.1 ± 1.4 mm. Thirty subjects from group B were exposed to a clinical examination; out of 37 sites with bone loss >0.5 mm in this subgroup, 29 sites had a PPD value of ≥4 mm. CONCLUSION: Marginal bone loss (>0.5 mm) at implants was observed in 30% of subjects and 16% of implant sites. More advanced loss of marginal bone occurred in much fewer subjects and sites. Sites with marginal bone loss was in the sub-sample characterized by bleeding on probing, but only occasionally with deep (≥6 mm) pockets.

Bone tissue in different parts of the edentulous maxilla and mandible.

BACKGROUND: The composition of the fully healed edentulous ridge of the posterior maxilla was recently examined and was found to contain about 50% mineralized bone and 16% bone marrow. AIM: The objective was to examine the composition of the tissue of the fully healed ridge in different portions of the maxilla and the mandible in partially dentate subjects. MATERIAL AND METHODS: Eighty-seven healthy subjects were included. A trephine drill was used to harvest hard tissue specimens. The biopsies were decalcified, embedded in paraffin, sectioned, stained, and examined using a point-counting procedure. RESULTS: The marginal portion of the jaws almost consistently contained a cortical cap that was significantly wider in the mandible than in the maxilla and twice as wide in the anterior as in the posterior segments of the mandible. Lamellar bone and bone marrow were the dominating tissue elements. Lamellar bone occupied about 63% of the tissue in the mandible and 46% in the maxilla. The maxilla contained about 23% bone marrow as compared to 16% in the mandible. In the mandible, 70% (anterior) and 57% (posterior) were made up of lamellar bone. In the maxilla, the proportion of lamellar bone in the anterior and posterior segments was similar (about 45%). Bone marrow occupied close to 40% of the anterior maxilla, while in the posterior maxilla and the anterior and posterior mandible marrow comprised between 13 and 18%. CONCLUSION: Marked differences existed with respect to tissue composition of the edentulous ridge between the maxilla and the mandible. The cortical crest was wider in the mandible than in the maxilla, and widest in the symphysis region of the mandible. The proportion of bone marrow was greater in the maxilla than in the mandible. The maxillary front tooth region was poor in lamellar bone but rich in bone marrow, while the anterior mandible contained large amounts of mineralized bone but small amounts of bone marrow.

Control of periodontal infections: a randomized controlled trial I. The primary outcome attachment gain and pocket depth reduction at treated sites.

OBJECTIVE: To compare the treatment outcome of scaling and root planing (SRP) in combination with systemic antibiotics, local antibiotic therapy and/or periodontal surgery. MATERIAL AND METHODS: One hundred and eighty-seven patients were assigned to eight groups treated by SRP plus none, one, two or three adjunctive treatments and monitored for 24 months in a randomized controlled clinical trial using a 2 × 2 × 2 factorial design. Systemic amoxicillin + metronidazole (SMA), local tetracycline delivery (LTC) and periodontal surgery (SURG) were evaluated as adjuncts. Changes in clinical attachment level (CAL) and probing pocket depth (PPD) were statistically evaluated by ancova of main effects. RESULTS: Effects of adjunctive therapy to SRP were minimal at 3 months. Between 3 and 6 months PPD reduction occurred particularly in patients receiving periodontal surgery. After 6 months, both CAL gain and PPD reduction reached a plateau that was maintained at 24 months in all groups. The 24-month CAL gain was improved by SMA (0.50 mm) while PPD was reduced by SMA (0.51 mm) and SURG (0.36 mm). Smoking reduced CAL gain and PPD reduction. CONCLUSION: Patients receiving adjunctive therapies generally exhibited improved CAL gain and/or PPD reduction when compared with the outcome of SRP alone. Only additive, not synergistic effects of the various adjunctive therapies were observed.