Bone Height Changes Research Articles

Immediate versus Delayed Loading of Mandibular Bar Retained Implant Overdenture

Immediate implant loading protocol is popular to patients' over the delayed loading protocol. Due to its high risks association, documented results were essential. Study objective; assess the bone height and density change using direct digital radiography in immediately loaded implants connected by a bar, and compare the results with those of the delayed loaded implants. 10 completely edentulous patients participated in a randomized controlled trial. All patients were treated by; conventional maxillary complete denture; mandibular overdenture supported by a prefabricated bar connecting two implants placed in the canine region. Patients were randomly divided into; test group (Group A) with immediate loaded implants and control group (Group B) with implants submerged and loaded three months after insertion. Intraoral direct digital radiography used to measurement marginal bone height level and radiodensitometric analysis of bone at intervals time of loading at 3, 6, 9 and 12 months. The result statistically revealed: an insignificant difference (p ≤ 0.05) in the mean marginal bone loss between both groups; a significant increase (p ≤ 0.05) in the bone density measurements adjacent to the immediately loaded implants from time of loading. In conclusion, immediate loading of two mandibular implants splinted passive bar is a predictable alternative treatment comparable to delayed loading.

Radiographic evaluation of marginal bone maintenance around tissue level implant and bone level implant: a randomised controlled trial. A 1‐year follow‐up

The etiologic factors associated with crestal bone loss have not been comprehensively clarified. Several theories exist as to the reason for the observed changes in crestal bone height following implant restoration. In the 1990s, the wide-diameter implants were commercially introduced. Initially, the implants were restored with standard-diameter abutments because of lack of matching prosthetic components. Long-term radiographic follow-up of these 'platform-switched' restored wide-diameter dental implants has demonstrated a smaller-than-expected vertical change in the crestal bone height around these implants that is typically observed around implants restored conventionally with prosthetic components of matching diameters. The aim of this randomised controlled study was to assess radiographically marginal bone level alterations in implants restored according to the platform-switching concept compared with traditionally restored implants. Fifty-four subjects to participate in this randomised controlled study were selected. Two groups were assigned at random: control group (56 implants were restored with standard matching-diameter abutments) and test group (58 implants were restored with medialised abutments). X-ray explorations were taken for peri-implant bone level at the minute the last cementing of the prosthesis and at 1-year follow-up. NHI Image was used to digitally process and manipulate the radiographic images and perform the measurements. Mean of bone loss with platform-switching implants was -0·01 mm, and the mean of bone loss with standard platform implant was 0·42 mm. Outcomes of this study indicated that the platform-switching design could preserve the crestal bone levels to 1-year follow-up. There was a statistically significant difference in marginal bone loss.

Resorption of fibular bone following mandibular reconstruction for osteoradionecrosis

Introduction: The free fibular flap (FFF) is commonly used for mandibular reconstruction due to its length, consistent blood supply and relative ease of harvest. The fibular bone has been demonstrated to maintain mass over time conferring a potential advantage over other osseous flaps. However when using the FFF in conjunction with a reconstruction plate resorption may occur secondary to stress shielding. There is no published literature of changes in fibular bone height in patients treated for osteoradionecrosis (ORN).

Cone beam computed tomography evaluations of marginal alveolar bone before and after orthodontic treatment combined with premolar extractions

Using cone beam computed tomography (CBCT) we investigated the distance between the cemento-enamel junction (CEJ) and the marginal bone crest (MBC) at buccal, lingual, mesial, and distal surfaces of incisors to first molars in adolescents before (baseline) and after extractive orthodontic treatment (study end point). Patients with Class I malocclusion, crowding and an overjet of ≤ 5 mm were examined with a CBCT unit using a 60 × 60-mm field of view and a 0.125-mm voxel size. Large differences in marginal bone height were found at baseline, particularly between tooth surfaces. There was a slight correlation between age and CEJ-MBC distance. From baseline to the study end point, large bone-height changes among teeth and tooth surfaces could be seen. Lingual surfaces, followed by buccal surfaces, showed the largest changes. Eighty-four per cent of lingual surfaces of mandibular central incisors exhibited a bone-height decrease of > 2 mm. The bone-height decrease was larger at lingual surfaces in the mandible than in the maxilla, and larger in girls (mean=1.8 mm) than in boys (mean=1.5 mm). Fewer than 1% of proximal surfaces exhibited changes of > 2 mm. It is unknown whether the changes in marginal bone height are transitory. A high-quality CBCT technique may help to determine this by providing a deeper insight into the long-term side effects of orthodontic treatment.

Bone Healing after Tooth Extraction with or without an Intervention: A Systematic Review of Randomized Controlled Trials

To assess whether the use of a graft and/or membrane post-tooth extraction improves healing of the site dimensionally, radiographically, and/or histologically. MEDLINE and EMBASE and the Cochrane Central register of controlled trials (CENTRAL) were searched up until August 2011. Randomized controlled trials that included and compared healing post-tooth extraction between a control (no intervention) and a graft and/or membrane (test) were selected. Titles and abstracts of 2,861 papers were screened. A total of 42 papers were selected for full text reading. Nine papers met the eligibility criteria and were selected for further analysis. Because of the varying graft materials used and the different methods of investigation, as well as the variation in follow-up times, a meta-analysis was not possible. The present review found that clinically, there was a range in loss of width in the control sites of 2.46 mm (SD 0.4 mm) to 4.56 mm (SD 0.33 mm) compared to 1.14 mm (SD 0.87 mm) to 2.5 mm (SD 1.2 mm) in the test sites. The range in loss of height in control sites was 0.9 mm (SD 1.6 mm) to 3.6 mm (SD 1.5 mm) compared to a gain of 1.3 mm (SD 2 mm) to a loss of 0.62 mm (SD 0.51 mm) in test sites. Radiographically a range of change in bone height of between 0.51 mm (No SD) to 1.17 mm (SD 1.23 mm) was noted in control sites compared to a change of between 0.02 mm (SD 1.2 mm) and 1 mm (SD 1.4 mm) in test sites. There is limited data regarding the effectiveness of alveolar ridge preservation therapies when compared to the control. Overall the socket intervention therapies did reduce alveolar ridge dimensional changes post-extraction, but were unable to prevent resorption. Histology did demonstrate a large proportion of residual graft material that may account for some of the difference in alveolar ridge dimensions at follow up.

Sinus bone formation and implant survival after sinus membrane elevation and implant placement: a 1‐ to 6‐year follow‐up study

To investigate the long-term clinical and radiographic results of the maxillary sinus membrane elevation technique where implants were inserted in a void space created by the elevation of the sinus membrane without adding any graft material. A total of 84 patients were subjected to 96 membrane elevation procedures and simultaneous placement of 239 implants. Changes of intra-sinus and marginal bone height in relation to the implants were measured in intraoral radiographs taken at insertion, after 6 months of healing, after 6 months of loading and then annually. Computerized tomography was performed pre-surgically and 6 months post-surgically. Resonance Frequency Analyses measurements were performed at the time of implants placement, at abutment connection and after 6 months of loading. The implant follow-up period ranged from a minimum of one to a maximum of 6 years after implants loading. All implants were stable after 6 months of healing. A total of three implants were lost during the follow-up period giving a survival rate of 98.7%. Radiography demonstrated on average 5.3±2.1 mm of intra-sinus new bone formation after 6 months of healing. RFA measurements showed adequate primary stability (implant stability quotient 67.4±6.1) and small changes over time. Maxillary sinus membrane elevation and simultaneous placement of implants without the use of bone grafts or bone substitutes result in predictable bone formation with a high implant survival rate of 98.7% during a follow-up period of up to 6 years. The intra-sinus bone formation remained stable in the long-term follow-up. It is suggested that the secluded compartment allowed for bone formation according to the principle of guided tissue regeneration. The high implant survival rate of 98.7% indicated that the implants sufficiently supported the fixed bridges throughout the study period. This technique reduces the risks for morbidity related to harvesting of bone grafts and eliminates the costs of grafting materials.

Randomized clinical trial on the efficacy ofEscherichia coli-derived rhBMP-2 with β-TCP/HA in extraction socket

PURPOSEThis randomized clinical trial was conducted to assess the safety and effectiveness of the ErhBMP-2 in alveolar bone regeneration as well as preservation of the β-TCP bone graft material that contains ErhBMP-2.MATERIALS AND METHODSThis study involved 72 patients at the 3 study centers. The patients, who were divided into 2 groups: the experiment group who had ErhBMP-2 coated TCP/HA and the control group who had TCP/HA graft material alone transplanted immediately after tooth extraction. CT was taken before and 3 months after the transplantation and healing status was compared between the two groups. The efficacy endpoints that were used to measure the degree of bone induction included alveolar bone height and 3 measurements of bone width. The paired t test was used to determine the significance of the changes (P<.05).RESULTSChanges in alveolar bone height were -1.087 ± 1.413 mm in the control group and -.059 ± 0.960 mm in the experimental group (P<.01). At 25% extraction socket length [ESL], the changes were 0.006 ± 1.149 mm in the control group and 1.279 ± 1.387 mm in the experimental group. At 50% ESL, the changes were 0.542 ± 1.157 mm and 1.239 ± 1.249 mm, respectively (P<.01 for 25% ESL, and P<.05 for 50% ESL). During the experiment, no adverse reactions to the graft material were observed.CONCLUSIONErhBMP-2 coated β-TCP/HA were found to be more effective in preserving alveolar bone than conventional β-TCP/HA alloplastic bone graft materials.

Loss of tooth-supporting bone in the koala (Phascolarctos cinereus) with age

This study investigated changes in alveolar bone height in free-ranging koalas of different age groups. Twenty-seven free-ranging Queensland koalas (15 female, 12 male), admitted to the Moggill Koala Hospital, Brisbane, were used in this study. Koalas were divided into three groups (young, adult, old) on the basis of tooth wear, each group containing nine animals. Defleshed jaws were examined for the presence of alveolar bone defects. The distance from the cemento-enamel junction and the interproximal crestal alveolar bone height was measured on the buccal aspects of the second and third molars. Jaws were photographed and radiographed. Bone defects (dehiscences and fenestrations) were observed in both jaws and were predominantly located on the buccal aspect of the alveolar process. The loss of height of crestal alveolar bone, relative to the cemento-enamel junction, increased with age, with 25 koalas showing moderate to severe bone loss and only two koalas having none/mild loss levels at all measurement sites. Female koalas had higher frequency of ‘none/mild’ cases of bone loss than did males. There was no variation in levels of alveolar bone loss between the upper and lower jaws or the corresponding right and left arches.

Maxillary anterior and mandibular posterior residual ridge resorption in patients wearing a mandibular implant-retained overdenture

The mandibular implant-retained overdenture could improve masticatory function compared to the conventional complete denture. However, increased forces exerted by the overdenture could increase residual ridge resorption of the maxillary anterior and mandibular posterior areas. The aim of this study was to compare the effect of the mandibular implant-retained overdenture using two or four dental implants, or the conventional complete denture on resorption of the residual ridge of the maxillary anterior and mandibular posterior areas over a period of 10 years. In total, 120 patients, 30 patients treated with an overdenture on two implants (two-implant group), 30 patients with an overdenture on four implants (four-implant group) and 60 patients treated with a conventional full denture (conventional group), participated in this study. On panoramic radiographs, made before and 10 years after treatment, proportional area measurements were applied to determine changes in bone height. After 10 years, a statistically significant amount of bone resorption had occurred in the anterior maxilla in the two-implant group and in the four-implant group. A significant amount of bone resorption had occurred in the posterior mandible in all three groups. There were no statistically significant differences between the groups in both areas. Patients presented large individual differences. It is concluded that patients rehabilitated with implant-retained mandibular overdentures are not subjected to more residual ridge resorption in the anterior maxilla when compared to patients wearing a conventional full denture. Regarding the mandibular posterior residual ridge, resorption was irrespective of wearing an implant-retained mandibular overdenture or a conventional mandibular denture.

Implant Restoration 3 Months after One Stage Sinus Lift Surgery in Severely Resorbed Maxillae: 2‐Year Results of a Multicenter Prospective Clinical Study

This multicenter prospective study was aimed to clinically evaluate implant behavior inserted in severely resorbed maxillae and restored 3 months after sinus grafting. In three clinical centers, 67 totally rough wide diameter implants were inserted during 30 consecutive sinus lifts. Computed tomography and panoramic analysis were preoperatively requested for each patient. Sinus grafting was performed using a nano-crystalline hydroxyapatite sole bone filler; no membrane was used to cover the buccal window. Preoperative residual bone height ranged between 1-4 mm (mean value: 2.70 mm, standard deviation [SD]: 0.9 mm). Uncovering procedure was carried out following 3 months of healing; 2 weeks later, a definitive restoration was seated using platform switching concept. To monitor stability changes, resonance frequency analysis was performed and implant stability quotient (ISQ) values were collected at the first surgery (baseline, T(0) ), at the abutment connection (T(1) ), and at 2-year follow-up (T(2) ). To measure bone changes, patients underwent panoramic analysis after 2-year follow-up. The image analysis software calculated the grafted bone height changes at level of implant site comparing preoperative and follow-up panoramic films; the software compensated for eventual radiographic distortion. Mean ISQ value was 35.7 (SD: 8.8) at baseline, 66.61 (SD: 4.76) at T(1) , and 77.9 (SD: 4.7) at T(2) . Statistically significant differences (p ≤ 0.005) regarding ISQ mean values were found between T(1) and T(0) , as well as between T(1) and T(2) . After 24 months of functional loading, only two implants were lost (cumulative survival rate: 97%). During the same observation period, the mean value of radiographic vertical height of grafted sinus was 13.75 mm (SD = 1.3 mm), with a mean gain of 11 mm. Within the limits of this study, despite preoperative residual bone height ranging 1 to 4 mm and absence of the membrane covering the buccal bone wall, maxillary sinus lift restoration 14 weeks after first surgery seems to be a reliable procedure using totally-rough surfaced implants restored using platform switching concept and nano-structured hydroxyapatite as sole bone filler.

Radiographic follow-up evaluation of sinus augmentation with deproteinized bovine bone and implant installation after loading

Computed tomography (CT) has been used in diagnosis and implant treatment, and CT can be used to assess the dimensional stability of graft materials after maxillary sinus augmentation. A 50-year-old male patient was treated for the simultaneous placement of implants with sinus augmentation and two post-operative CT scans were performed after the delivery of the prosthesis at 9 months and 15 months after the operation. There were no significant changes in alveolar bone height and the buccal window seemed to show remodeling over time. The continuity of the defect and the cortication were apparent in the 15-month post-operative CT scan. Implants installed simultaneously with sinus augmentation were well in function and the graft material seemed to be stable in maintaining tissue dimensions after the loading of the implants. The presented results need to be validated in further large case series or case-controlled studies.

Outcome of Brånemark Novum® Implant Treatment in Edentulous Mandibles: A Retrospective 5‐Year Follow‐Up Study

A gradual progression from a two-stage surgical technique to a one-stage and even immediate surgical protocol has occurred during the last decade with most oral implant systems. However, every new approach must obviously be reported individually, with long-term results, in order to assess whether the changes have any real patient value. The aim of the present report was to retrospectively review the 5-year outcome of patients treated with the Brånemark Novum (Nobel Biocare AB, Göteborg, Sweden) protocol. The first 15 patients treated according to the Novum procedure in a private specialist clinic in Lovere, Italy, were followed-up with clinical, radiographic, and resonance frequency analyses. All the patients' fixed constructions had been in function for an average of 5 years. Parameters recorded were implant survival, prosthesis success, oral hygiene and mucosal health, marginal bone remodeling, type and frequency of complications, and patient's opinion of the treatment outcome. After 5 years, the cumulative survival rate for implants was 91%, and for inserted bridge constructions it was 87%. Very small changes in implant stability occurred during implant loading from 1 to 5 years. Oral health conditions were good; 87% of mucosal quadrants around the implants were free from signs of inflammation. Very small marginal bone height changes were observed at the implants during the examination period, and except for four implant losses reported, severe complications were few. All patients were satisfied with the functional outcome of their constructions, but two patients were not completely happy with the aesthetics of their bridgework as supplied. This report shows 5-year evidence of acceptably good results with the Brånemark Novum implant technique in edentulous mandibles, when using only three implants to support the fixed bridge construction, and as long as inserted implants become and remain osseointegrated.

Computed Tomographic Evaluation of Sinus Augmentation with Simultaneous Endosseous Implant Placement

Computed tomography (CT) has become the gold standard by which a comprehensive implant treatment plan is determined and a postoperative assessment of cancellous and cortical bone is achieved. A patient with an insufficient alveolar bone height and sinus pneumatization was treated for the simultaneous placement of implants with sinus augmentation. CT scans were used not only for the presurgical evaluation, but also for the postoperative radiographic observation. The new sinus floor seemed to be more defined as time goes on and the decrease in alveolar bone height could not be found. The cortication and remodeling of the buccal window were apparent in the 10-month postoperative CT scan. No significant change in alveolar bone height was seen between the 6- and 10-month postoperative measurements. Implants placed simultaneously with the sinus augmentation procedure were maintained in a healthy condition up to 18 months and it was shown that CT scans can serve as a good follow-up tool in assessing postoperative results.

Pivotal, Randomized, Parallel Evaluation of Recombinant Human Bone Morphogenetic Protein-2/Absorbable Collagen Sponge and Autogenous Bone Graft for Maxillary Sinus Floor Augmentation

The purpose of this prospective study was to evaluate the safety and effectiveness of recombinant human morphogenetic protein-2 (rhBMP-2) on an absorbable collagen sponge (ACS) compared with an autogenous bone graft when used for 2-stage maxillary sinus floor augmentation. The study assessed new bone formation, placement integration, and functional loading after 6 months and long term for 2 years. A total of 160 subjects were randomized, enrolled, and followed from January 1999 to February 2004 at 21 centers in the United States. The subjects with less than 6 mm of native bone height were treated with 1.50 mg/mL rhBMP-2/ACS or with an autograft. The height and density measurements were quantified by computed tomography scans. Core biopsies were obtained at dental implant placement and used for histological analysis. Safety was evaluated by oral examinations, radiographs, serum chemistries, and hematology. A significant amount of new bone was formed by 6 months postoperatively in each group. The mean change in bone height in the rhBMP-2/ACS subjects was 7.83 +/- 3.52 mm versus 9.46 +/- 4.11 mm for the bone graft subjects. At 6 months after dental restoration, the induced bone in the rhBMP-2/ACS group was significantly denser than that in the bone graft group. No marked differences were found in the histologic parameters evaluated between the 2 groups. The new bone was comparable to the native bone in density and structure in both groups. The success rate for the rhBMP-2/ACS group was 79% (64 of 81 subjects), and 201 of 251 implants placed in the bone graft group and 199 of 241 implants placed in the rhBMP-2/ACS group were integrated, retained, and functional at 6 months after loading. No adverse events were deemed related to the rhBMP-2/ACS treatment. The autograft group was noted to have a 17% rate of long-term parasthesia, pain, or gait disturbance related to the bone graft harvest. The results of our multicenter, randomized, prospective, clinical trial have shown the effectiveness and safety of rhBMP-2/ACS compared with bone graft for sinus floor augmentation. The study's primary endpoint was exceeded, and the implants placed in rhBMP-2/ACS and bone graft groups performed similarly after functional loading.

A randomized, controlled clinical trial to evaluate a new membrane for guided bone regeneration around dental implants

The use of barrier membranes in guided bone regeneration (GBR) procedures for the treatment of alveolar bone defects is common practice. The objective of this study was to test whether a synthetic bioresorbable polyethylene glycol (PEG) hydrogel membrane could result in a similar amount of vertical bone fill as a standard collagen membrane, both combined with a membrane supporting material. The study enrolled 37 patients requiring implant treatment with an expected osseous defect in the posterior maxilla or mandible. After raising a mucoperiosteal flap, the implant sites were prepared and dental implants placed. The defect height was then measured and defects <3 mm were excluded from the study. Defects were grafted with bovine bone mineral and randomly covered with either a collagen membrane (control group, 18 patients) or a PEG hydrogel membrane (test group, 19 patients), which is applied as a liquid. After a healing period of 6 months, surgical re-entry was performed and the change in vertical bone height from baseline evaluated. Well-vascularized hard tissue was apparent at all sites and the regenerated bone was similar to the surrounding native bone. Mean vertical defect fill after 6 months was 5.63+/-1.84 mm at test sites and 4.25+/-1.16 mm at control sites, and the mean defect fills were 94.9% and 96.4% at test and control sites, respectively. More soft tissue complications were observed with the PEG membrane (e.g., delayed or incomplete wound healing) but all sites recovered uneventfully. The new PEG hydrogel membrane was as successful as a standard collagen membrane in the treatment of bony dehiscence defects around dental implants with simplified clinical handling.

In vivo evaluation of crestal bone heights following implant placement with ′flapless′ and ′with-flap′ techniques in sites of immediately loaded implants

To evaluate and compare the changes in crestal bone height around implants placed with flapless surgery and with-flap surgery. Ten implants were placed in six patients--five using flapless and five using with-flap techniques. Single-piece root-form implants and a one-stage approach with immediate nonfunctional loading protocol were used. The change in heights of crestal bone was measured on standardized digital periapical radiographs taken at 0, 1, and 3 months. On mesial side, the mean change from months 0-1, months 1-3, and months 0-3 for flapless method was significantly lower than with-flap method [0.01-0.06 mm for flapless and 0.13-0.40 mm for with-flap ( P = 0.01)]. On the distal side, the mean change from months 0-1, months 1-3, and months 0-3 for flapless method was significantly lower than with-flap method [0.02-0.05 mm for flapless and 0.09-0.30 mm for with-flap ( P = 0.01)]. During the three-month period, reduction of crestal bone height around the implants placed with flapless surgery (0.06 mm) was not statistically significant, while the reduction of crestal bone height around the implants placed using with-flap surgery (0.4 mm) was statistically significant. Comparitively, flapless approach showed lesser crestal bone height reduction, which was statistically significant.

Vertical alveolar crest bone maintenance around implants in two-stage surgery: an in situ study in dogs

The aim of this study was to evaluate in situ changes in the alveolar crest bone height around immediate implant-supported crowns in comparison to tooth-supported crowns (control) with the cervical margins located at the bone crest level, without occlusal load. In Group I, after extraction of 12 mandibular premolars from 4 adult dogs, implants from Branemark System (MK III TiU RP 4.0 x 11.5 mm) were placed to retain complete acrylic crowns. In Group II, premolars were prepared to receive complete metal crowns. Sixteen weeks after placement of the crowns (38 weeks after tooth extraction), the height of the alveolar bone crest was measured with a digital caliper. Data were analyzed statistically by the Mann-Whitney test at 5% significance level. The in situ analysis showed no statistically significant difference (p=0.880) between the implant-supported and the tooth-supported groups (1.528 + 0.459 mm and 1.570 + 0.263 mm, respectively). Based on the findings of the present study, it may be concluded that initial peri-implant bone loss may result from the remodeling process necessary to establish the biological space, similar to which occurs with tooth-supported crowns.

Inflammatory mediator release following bone grafting in humans: a pilot study

The aim of this pilot study was to track markers of periodontal inflammation and bone resorption associated with decalcified freeze-dried bone allografts. Eleven subjects completed standardized treatment of intrabony defects > or =3 mm with allografts. Gingival crevicular fluid was collected from the defect site and an adjacent interproximal site within the surgical field at baseline, 2, 4, and 8 weeks post-operatively, and analysed for biochemical markers of inflammation/bone resorption. Probing depth, recession, bleeding on probing, plaque, and 6-month radiographic bone height change were measured. Both prostaglandin E(2) (p=0.007) and bone-specific type 1 collagen (p=0.01) increased in crevicular fluid after 2 weeks in the bone graft sites. Matrix metalloproteinase-9 levels remained constant over time. There were positive correlations between prostaglandin levels during the first 8 weeks and bone height change over 6 months. Periodontal bone grafts stimulate an inflammatory response during the first 2 weeks post-operatively, and the potential negative effects of inhibiting prostaglandins post-operatively should be investigated further.

Inter‐Implant Bone Height Changes in Anterior Maxillary Immediate and Non‐Immediate Adjacent Dental Implants

The purpose of this study was to evaluate inter-implant bone crest height changes between immediate and non-immediate dental implants placed in the anterior maxillary region. A retrospective study was conducted on consecutively treated patients requiring at least two adjacent implants in the anterior maxillary region that were placed in the same operation during 1994 to 2004. Files of 45 healthy patients reporting 200 implants were reviewed. Age, gender, smoking status, and implant characteristics (coating and dimensions) were recorded. Inter-implant bone measurements were taken on two panoramic radiographs from each patient: one after implant placement and the other at the last follow-up. The distance between adjacent implants was measured at the implant-abutment interface (implant platform). Overall, 130 inter-implant gaps were found. Follow-up ranged from 8 to 146 months. Two-tailed Pearson correlation tests revealed a negative correlation between inter-implant distance and bone loss (P = 0.036). Mean peak-crest bone loss for immediate implants was higher than for delayed implants (P = 0.026). There was more bone loss when hydroxyapatite (HA)-coated implants were used, although no statistical significance was observed. No statistically significant difference was found between the different locations in the anterior maxilla. No correlation was found between patient's age, smoking habits, and bone loss or between follow-up time and bone loss. A negative correlation was found between inter-implant distance and bone loss at the inter-implant bone crest in the anterior maxillary region. Bone loss was small in this study cohort.

Granulocyte elastase in gingival crevicular fluid: improved monitoring of the site-specific response to treatment in patients with destructive periodontitis.

In 13 patients with severe destructive periodontitis, the response to periodontal therapy was estimated by granulocyte elastase level in gingival crevicular fluid (GCF). 62 sites were classified according to changes of probing depths (PD) and quantitative bone height (BH%) before and after 5-year regular maintenance treatment: (i) 17 consistently healthy sites with no changes of PD and BH%; (ii) 6 initially healthy sites with deterioration in PD and BH%; (iii) 14 diseased sites with improvement in PD and BH%; (iv) 25 diseased sites with no improvement in PD and BH%. GCF was collected by an intracrevicular washing system. The released elastase in the supernatants (EA-S) and the cell-bound elastase in the pellets (EA-P) were determined with a low molecular weight substrate specific for granulocyte elastase. The ratio of EA-S and EA-P (S/P-ratio) was used as a relative measure of elastase released by the granulocytes present. The sites classified as diseased with no improvement or initially healthy but deteriorating, had significantly higher EA-S, EA-P and S/P-ratios than the consistently healthy sites or diseased but improving sites (p < 0.01). Both EA-S and S/P-ratio showed strongly positive correlations with the current levels of gingival inflammation and periodontal destruction (p < 0.001). The present study suggests that increased elastase level is associated with disease progression, and may be used to monitor the response to longitudinal maintenance therapy.