Post-treatment stability after 5 years of retention with vacuum-formed and bonded retainers-a randomized controlled trial.

BACKGROUND: Retention after orthodontic treatment is still a challenge and more evidence about post-treatment stability and patients' perceptions of different retention strategies is needed. OBJECTIVES: This trial compares removable vacuum-formed retainers (VFR) with bonded cuspid-to-cuspid retainers (CTC) after 5 years of retention. TRIAL DESIGN: A single centre two-arm parallel-group randomized controlled trial. METHODS: This trial included 104 adolescent patients, randomized into two groups (computer-generated), using sequentially numbered, opaque, and sealed envelopes. All patients were treated with fixed appliances in both jaws with and without tooth extractions. Patients in the intervention group received a VFR in the mandible (n = 52), and patients in the active comparator group received a CTC (n = 52). Both groups had a VFR in the maxilla. Dental casts at debond (T1), after 6 months (T2), after 18 months (T3), and after 5 years (T4) were digitized and analysed regarding Little's Irregularity Index (LII), overbite, overjet, arch length, and intercanine and intermolar width. The patients completed questionnaires at T1, T2, T3, and T4. RESULTS: Post-treatment changes between T1 and T4 in both jaws were overall small. In the maxilla, LII increased significantly (median difference: 0.3 mm), equally in both groups. In the mandible, LII increased significantly in the group VFR/VFR (median difference: 0.6 mm) compared to group VFR/CTC (median difference: 0.1 mm). In both groups, overjet was stable, overbite increased, and arch lengths decreased continuously. Intercanine widths and intermolar width in the mandible remained stable, but intermolar width in the maxilla decreased significantly. No differences were found between groups. Regardless of retention strategy, patients were very satisfied with the treatment outcome and their retention appliances after 5 years. LIMITATIONS: It was not possible to perform blinded assessments of digital models at follow-up. CONCLUSIONS: Post-treatment changes in both jaws were small. Anterior alignment in the mandible was more stable with a bonded CTC retainer compared to a removable VFR after 5 years of retention. Patients were equally satisfied with fixed and removable retention appliances. TRIAL REGISTRATION: ClinicalTrials.gov (NCT03070444).

Vacuum-formed retainers and bonded retainers for dental stabilization-a randomized controlled trial. Part II: patients' perceptions 6 and 18 months after orthodontic treatment.

OBJECTIVE: To compare removable vacuum-formed Essix C retainers with bonded cuspid-to-cuspid retainers (CTCs) regarding patients' perceptions after debonding and 6 and 18 months of retention. TRIAL DESIGN: A single-centre two-arm parallel-group randomized controlled trial. METHODS: This trial included 104 adolescent patients, computer-generated randomized, with sequentially numbered, opaque and sealed envelopes, into two groups and stratified by gender. They were treated with fixed appliances with and without tooth extractions in both jaws and were ready for debond. Patients in the intervention arm received a vacuum-formed retainer (VFR) in the mandible (n = 52), and patients in the active comparator arm received a CTC (n = 52). Both groups had a VFR in the maxilla. Treatment outcome satisfaction, quality of care and attention, side-effects during the retention phase, and retainer acceptance and compliance were assessed with questionnaires at baseline (T1, 2 weeks after debond) and after 6 (T2) and 18 months (T3) of retention. Operator was blinded to group assignment during measurements. RESULTS: Ninety-five patients completed the questionnaires at all three time points. Patients were overall satisfied with treatment outcome, quality of care and attention, and how their retainers worked at all three time points, with no differences between groups. At T1 and T3, the VFR group reported significantly more pain and discomfort (T1: P = 0.005, T3: P < 0.0001) and soreness (T1: P = 0.001, T3: P = 0.011) in the mandible compared to the CTC group. The CTC group found it easier to get used to their retainers. After 18 months, 70.5 per cent in the VFR group and 73.9 per cent in the CTC group reported the recommended wear-time of the VFRs. Decreased wear-time was correlated to perceived pain and discomfort (rs = -0.421, P < 0.0001). LIMITATIONS: The results were limited by our retainer design and recommended wear regimen. CONCLUSIONS: Both groups reported high treatment outcome satisfaction and low levels of side-effects during the retention phase. Nevertheless, the VFR group reported more pain and discomfort at T1 and at T3. Self-reported compliance was the same in both groups. The VFR group was more concerned about relapse. TRIAL REGISTRATION: NCT03070444 (https://clinicaltrials.gov).

Comparison of a polyethylene glycol membrane and a collagen membrane for the treatment of bone dehiscence defects at bone level implants-A prospective, randomized, controlled, multicenter clinical trial.

OBJECTIVES: The aim of the present randomized, controlled clinical multicenter trial was to compare a polyethylene glycol (PEG) and a native collagen membrane (BG) for simultaneous guided bone regeneration at bony dehiscence-type defects around bone level titanium implants. MATERIAL AND METHODS: The study enrolled 117 patients requiring implant treatment in the posterior maxilla or mandible with expected buccal bony dehiscence-type defects at the placed titanium implants. According to a parallel groups design, defects were filled with a synthetic bone filler and randomly assigned to either PEG or BG membrane. As primary parameter, the relative vertical bone fill was assessed at baseline and at re-entry after 6 months of healing. As secondary parameters, the marginal bone level (MBL) was assessed radiographically and soft tissue conditions were recorded up to 18 months postloading. RESULTS: Both groups showed comparable vertical bone fill revealing a relative change in defect height of 59.7% (PEG) and 64.4% (BG). The absolute mean reduction in defect size was 2.5 mm in the PEG group and 3.2 mm in the BG group. Although both groups revealed a statistically significant mean defect reduction (p < .001), a comparison between the two groups did not show statistical significances. The non-inferiority test with inferiority limit of -5% could not be rejected, based on the 90% confidence interval of the differences of the two means with lower limit -15.4%. After 18 months, an MBL increase of 0.45 ± 0.43 mm in the PEG group and 0.41 ± 0.81 mm in the BG group was detected (p < .001). Soft tissue complications were observed in both groups without showing statistical significance. CONCLUSIONS: Both membranes supported bone regeneration at dehiscence-type defects and obtained vertical bone fill with a relative change in defect height of 59.7% (PEG) and 64.4% (BG); however, the non-inferiority of PEG could not be shown.

Histological and histomorphometrical outcome after lateral guided bone regeneration augmentation of the mandible with different ratios of deproteinized bovine bone mineral and autogenous bone. A preclinical in vivo study.

OBJECTIVE: To test the hypotheses of no differences in (I) percentage of bone (POB), non-mineralized tissue (NMT), and deproteinized bovine bone mineral (DBBM), and (II) ingrowth of mineralized bone after lateral guided bone regeneration (GBR) augmentation of the mandible with different ratios of DBBM and particulate autogenous bone (PAB) at different time points. MATERIAL AND METHODS: Twenty-four minipigs were randomly allocated into three groups. Lateral augmentation in 96 sites (4 in each animal) was performed unilaterally with a standardized quantity of grafting material in each animal with different ratios of DBBM and PAB (50:50, 75:25, 100:0) and autogenous bone block in combination with DBBM and covered with a collagen membrane. The percentage of different tissues in the graft and ingrowth of mineralized bone was assessed by histomorphometrical and histological analyses after 10, 20, and 30 weeks, respectively. RESULTS: The POB was 54% (50:50), 50% (75:25), and 48% (100:0) after 10 weeks, 60% (50:50), 61% (75:25), and 60% (100:0) after 20 weeks, and 63% (50:50), 62% (75:25), and 62% (100:0) after 30 weeks. There was no significant difference between the groups at any time points. There was a significant increase in POB and a significant decrease in NMT for 75:25 and 100:0 from 10 to 30 weeks. All ratios demonstrated a non-complete ingrowth of mineralized bone into the graft after 10 weeks and complete mineralization after 30 weeks. CONCLUSION: Within the limitations of the present study, it seems like addition of autogenous bone to DBBM for LRA did not affect the bone formation nor graft incorporation after 10-30 weeks of healing. However, a prolonged healing time seems to result in an increased POB for all ratios.

Vacuum-formed retainer versus bonded retainer for dental stabilization in the mandible-a randomized controlled trial. Part I: retentive capacity 6 and 18 months after orthodontic treatment.

BACKGROUND: Evidence concerning the most appropriate retention strategy after orthodontic treatment is still inconclusive. OBJECTIVE: This trial compares the retentive capacity of vacuum-formed Essix C-retainers (VFR) and bonded cuspid-to-cuspid retainers (CTC) in the mandible 6 and 18 months after orthodontic treatment. TRIAL DESIGN: A single-centre two-arm parallel-group randomized controlled trial. METHODS: This study included 104 adolescent patients, computer-generated randomized with sequentially numbered, opaque, and sealed envelopes into two groups and stratified by gender (52 females and 52 males). The patients were treated with fixed appliances with and without tooth extractions in both jaws and were ready for debond. In the intervention arm, patients received a VFR (n = 52); in the active comparator arm, patients received a CTC (n = 52). Dental casts were obtained at debond (T1), after 6 months (T2), and after 18 months (T3). The casts were digitized. The retentive capacity was evaluated on digital three-dimensional models using Little's Irregularity Index (LII), overbite, overjet, arch length, and intermolar and intercanine width. RESULTS: Baseline values were similar for both groups. Statistically significant increases were noted in LII and overbite, mainly between T1 and T2, but also between T1 and T3 in the VFR group (LII = 0.52 mm, P < 0.001, overbite = 0.51 mm, P < 0.001) and in the CTC group (LII = 0.45 mm P < 0.001, overbite = 0.36 mm, P < 0.001). There were no significant differences between groups. Overjet showed small variations during the observation periods but was overall stable within and between groups after 18 months. Arch length decreased slightly in both groups after 6 and 18 months. Intermolar and intercanine widths remained stable after debond. LIMITATIONS: Patients, operator, and outcome assessor could not be blinded due to the study design. CONCLUSIONS: VFR and CTC have the same retention capacity in the mandible after 6 and 18 months. Relapse mainly occurs during the first 6 months of retention, but the post-treatment changes are generally small. Shorter VFRs in the mandible do not cause negative vertical effects. Part-time wear regimen is not associated with increased relapse. TRIAL REGISTRATION: NCT03070444.

Osteotome-Mediated Sinus Floor Elevation With or Without a Grafting Material: A Systematic Review and Meta-analysis of Long-term Studies (≥5-Years).

OBJECTIVE: To test the hypothesis of no difference in the long-term treatment outcome after osteotome-mediated sinus floor elevation with or without a grafting material. MATERIALS AND METHODS: A MEDLINE/PubMed, Cochrane Library, and EMBASE search in combination with a hand-search of relevant journals was conducted, including human studies published in English from January 1, 1986 to December 1, 2017. RESULTS: One comparative and 7 noncomparative studies fulfilled the inclusion criteria. Survival of suprastructures had never been compared within the same study. Meta-analysis demonstrated an overall estimated patient-based implant survival of 94%. Gain in vertical alveolar bone height was similar with the 2 treatment modalities. Noncomparative studies demonstrated high long-term survival rate of suprastructures and implants with the 2 treatment modalities, as well as limited periimplant marginal bone loss. CONCLUSION: High long-term implant survival was demonstrated after osteotome-mediated sinus floor elevation with or without a grafting material. However, long-term randomized controlled trials comparing the 2 treatment modalities are sparse. Hence, conclusions drawn from this systematic review should be interpreted with caution.

Sinus floor elevation procedures to enable implant placement and integration: techniques, biological aspects and clinical outcomes.

Implant treatment in an atrophied edentulous posterior maxilla constitutes a challenge for the therapeutic team. The authors of the present study acknowledge that modern micro-rough surface implants in lengths of about 8-10 mm or longer and of different brands are similarly successful. Consequently, the authors propose that the use of different sinus floor elevation techniques should be considered when < 8 mm of bone is available below the maxillary sinus. The type of sinus floor elevation technique selected is mainly based on residual vertical bone height, marginal bone width, local intrasinus anatomy and the number of teeth to be replaced, although other factors (such as surgical training and surgical experience) may have an impact. It is proposed that a transcrestal sinus floor elevation approach can be considered as a first-choice method for single tooth gaps in situations with sufficient width for implant placement and a residual bone height of 5-8 mm, while lateral sinus floor elevation, with or without grafting materials, is indicated when < 5 mm of bone is available and when several teeth are to be replaced. With regard to time of implant placement, a one-stage procedure is preferred provided that high primary stability can be ensured.

Sinus Floor Augmentation Using Straumann® BoneCeramic™ and Bio-Oss® in a Split Mouth Design and Later Placement of Implants: A 5-Year Report from a Longitudinal Study.

BACKGROUND: Straumann® BoneCeramic™ is a synthetic biphasic calcium phosphate (BCP) aimed for sinus floor augmentation. Long-term follow-up of implants placed in BCP after sinus augmentation is still missing. PURPOSE: The primary aim of the study was to compare survival rates and marginal bone loss of Straumann SLActive implants placed in either BCP (test) or Bio-Oss® (DBB) (control) after sinus floor augmentation. The secondary aim was to calculate graft sinus height at different time points. MATERIALS AND METHODS: Bilateral sinus floor augmentation was performed in a split mouth model. Eleven patients (mean age 67 years) received 100% BCP on one side and 100% DBB on the contralateral side. After 8 months of graft healing, 62 Straumann SLActive implants were placed. After 5 years of functional loading (6 years after augmentation) of implants, marginal bone levels and grafted sinus height were measured, and implant survival and success rates were calculated. RESULTS: After 5 years of loading, all prosthetic constructions were in function although two implants were lost in each grafting material. The overall implant survival rate was 93.5% (91.7% for BCP, 91.3% for DBB, and 100% for residual bone). The success rates were 83.3% and 91.3% for BCP and DBB, respectively. There was no statistically significant difference in mean marginal bone level after 5 years between BCP (1.4 ± 1.2 mm) and DBB (1.0 ± 0.7 mm). Graft height reduction (GHR) after 6 years was limited to 6.6% for BCP and 5.8% for DBB. CONCLUSION: In this limited RCT study, the choice of biomaterial used for sinus floor augmentation did not seem to have any impact on survival rates and marginal bone level of the placed implants after 5 years of functional loading and GHR was minimal.

A randomized and controlled clinical trial of two different compositions of deproteinized bovine bone and autogenous bone used for lateral ridge augmentation.

OBJECTIVE: The aim of the study was to radiologically and histologically evaluate the graft healing and volumetric changes after lateral augmentation with two different compositions of deproteinized bovine bone (DPBB) and autogenous bone (AB). MATERIAL AND METHODS: Thirteen patients with a mean age of 59.6 ± 12.1 years (six men and seven women) were included in this randomized and controlled trial, designed as a split-mouth study. Ten edentulous and four partially edentulous jaws with an alveolar ridge width of ≤4 mm were laterally augmented with a graft composition of 60 : 40 (DPBB/AB) on one side and 90 : 10 (DPBB/AB) on the contralateral side. Cone beam computed tomography (CB/CT) was obtained immediately postoperatively and after a healing period of 7.5 months. Width changes were measured on CB/CT scans. After a mean healing period of 8.1 months (range, 7.9-8.3), biopsies were retrieved perpendicular to the crest from each graft by means of a trephine bur. Histomorphometry was performed, and the following variables were recorded: Ingrowth of new bone (percentage of total graft width), percentage of DPBB, bone and soft tissue, and percentage of DPBB particles in contact with bone. RESULTS: The mean gained width of the alveolar crest after 7.5 months was significantly more for the 60 : 40 mixture compared with the 90 : 10 mixture, 3.5 (±1.3) mm and 2.9 (±1.3) mm, respectively. There was a significant difference in graft width reduction between 60 : 40 and 90 : 10 after 7.5 months, 37 (±19.9)% and 46.9 (±23.5)%, respectively. New bone ingrowth had occurred in 82.1 (±23.3)% and 82.3 (±26.6)% of the graft, respectively. There were no statistical differences between fractions of different tissues between the 90 : 10 and 60 : 40 compositions. However, there were significantly more soft tissue and less new bone formation closer to the periosteum compared with the graft portion closer to the residual bone in both 60 : 40 and 90 : 10 compositions. CONCLUSIONS: There was significantly less graft width reduction with a mixture of 60 : 40 (DPBB/AB) compared with a mixture of 90 : 10 composition, but the results from the histomorphometry showed no statistical differences comparing the groups.

A 10-year clinical and radiographic study of implants placed after maxillary sinus floor augmentation with an 80:20 mixture of deproteinized bovine bone and autogenous bone.

BACKGROUND: There is a need for prospective, long-term follow-up studies of implants placed after maxillary sinus floor augmentation (MSFA). PURPOSE: The aim of the present study was to determine whether deprotenized bovine bone (DPBB) used for MSFA may result in long-term stability of placed dental implants. MATERIAL AND METHODS: Fourteen of the 20 patients included in the study were followed throughout the 10 years study period. These patients had 53 implants placed in 22 (6 unilateral and 8 bilateral) maxillary sinuses augmented with a mixture of 80% DPBB and 20% autogenous bone (80:20), and 15 implants placed in non-grafted sites. Clinical and radiographic examinations of the implants and grafts were performed. RESULTS: After 10 years of functional loading 15 of the initially placed 108 implants had been lost giving a cumulative survival rate of 86%. The mean marginal bone loss was 1.6 ± 1.0 mm. There were no statistically significant differences in marginal bone level, pocket depth, or ISQ-values between implants placed in residual or grafted bone or between smokers or non-smokers at 10 years follow-up. There was a statistically significant reduction (p < .01) in graft height between 3 months and 2 years but no further significant reduction up to 10 years. CONCLUSIONS: The first 2 years after placement of implants with turned surfaces placed in sites after sinus floor augmentation with DPBB and autogenous bone seem to be critical for implant survival. At 10 years follow-up, the remaining implants presented excellent clinical and radiological results regardless of smoking habits or implant sites (augmented or residual bone).

A 3-year clinical follow-up of implants placed in two different biomaterials used for sinus augmentation.

PURPOSE: The aims of the present study were to compare a novel biphasic calcium phosphate (BCP) with deproteinized bovine bone (DBB) for maxillary sinus floor augmentation in a split-mouth design and to perform a clinical follow-up of dental implants placed in the augmented sinuses. MATERIALS AND METHODS: Partially or completely edentulous patients requiring bilateral sinus augmentation were included in the study. The patients were randomized for augmentation with BCP (test) and DBB (control) in the contralateral side. Eight months after grafting, dental implants were placed. After 3 years of graft healing, core biopsy specimens were obtained from the grafted areas for histologic and histomorphometric analyses. After 3 years of functional implant loading, implant survival/success rates and clinical indices were assessed and radiographic examination and resonance frequency analysis were performed. RESULTS: Nine completely edentulous patients and two partially edentulous patients (mean age, 67 years) who required bilateral sinus augmentation were included in the study, and 62 implants were placed. The mean values for the area of newly formed bone in the retrieved specimens were 29% ± 14.3% and 32% ± 18.0% for BCP and DBB, respectively; the percentage of graft particles in contact with bone was 38% ± 10.9% in the BCP group and 44% ± 12.1% in the DBB group (no statistical significant differences between groups). The mean values for the area of BCP particles and DBB particles were 20% ± 7.5% and 24% ± 13.5%, respectively (difference not significant). One dental implant was lost from each group, resulting in an overall implant survival rate of 96.8% after 3 years of loading. CONCLUSION: After 3 years, a similar amount of newly formed bone was present regardless of the biomaterial used. The choice of biomaterial did not seem to influence implant survival rates.

A prospective 1-year clinical and radiographic study of implants placed after maxillary sinus floor augmentation with synthetic biphasic calcium phosphate or deproteinized bovine bone.

BACKGROUND: The technique of using bone grafts or different biomaterials for augmentation of the maxillary sinus prior to implant placement is well accepted by clinicians. However, clinical documentation of some bone substitutes is still lacking. PURPOSE: This prospective study was designed to evaluate the success rate of implants placed after maxillary sinus augmentation with a novel synthetic biphasic calcium phosphate (BCP) or deproteinized bovine bone (DBB), the latter acting as control. MATERIAL AND METHODS: Nine edentulous patients and two partially edentulous patients with a mean age of 67 years with a bilateral need for sinus augmentation, < 5 mm residual bone in the floor of the sinus and a crestal width ≥ 4 mm, were included in the study. After bilateral elevation of the Schneiderian membrane, all patients were randomized for augmentation with synthetic BCP in one side and DBB in the contralateral side. After 8 months of graft healing, 62 implants with an SLActive surface were placed. Implant survival, graft resorption, plaque index, bleeding on probing, sulcus bleeding index, probing pocket depth, and implant success rate were evaluated after 1 year of functional loading. RESULTS: After a mean of 118 days, all patients received their fixed prosthetic constructions. One implant was lost in each biomaterial, giving an overall survival rate of 96.8%. Success rates for implants placed in BCP and DBB were 91.7 and 95.7%, respectively. No significant difference in marginal bone loss was found around implants placed in BCP, DBB, or residual bone, respectively. The mean graft resorption was 0.43 mm (BCP) and 0.29 mm (DBB). CONCLUSION: In this limited study, implant success rate was not dependent on the biomaterial used for maxillary sinus augmentation. Similar results were found after 1 year of functional loading for implants placed after sinus augmentation using BCP or DBB.

A clinical and histological case series study on calcium sulfate for maxillary sinus floor augmentation and delayed placement of dental implants.

BACKGROUND: Maxillary sinus floor augmentation is a procedure that is indicated in cases when the volume of the posterior maxillary bone is inadequate. The goal of this treatment is to obtain sufficient amount of bone tissue in order to gain osseointegration of endosseous implants. PURPOSE: The purpose of this study was to conduct a clinical and histological analysis of calcium sulfate (CaS) as bone graft substitute in sinus floor augmentation. MATERIAL AND METHODS: Ten patients with edentulous maxillas were included in this study. They had moderate to severe atrophy of the posterior maxilla. Surgiplaster (Classimplant®, Rome, Italy) was used as graft material in the maxillary sinus and was covered by BioGide® (Geistlish Pharmaceutical, Wolhusen, Switzerland). After 4 months of graft healing, 40 dental implants were placed and a biopsy for histomorphometry was taken at these occasions. The specimens were viewed by light microscope, and the extent of bone regeneration and remaining graft material was evaluated. Radiographs were taken at the time of sinus augmentation and after 4 months of graft healing. RESULTS: At the time of abutment surgery, one implant was considered as a failure and was consequently removed, giving a survival rate of 97.5% after 1 year of loading. Radiographs showed a mean of 26.5% shrinkage of the augmented area. A significant resorption of CaS was noted with a mean value of 8.8% of remaining graft material after 4 months of healing. The biopsies also revealed new bone formation with a mean value of 21.2% of the total biopsy area. Histology showed signs of an acellular substitution of CaS with bone-like tissue. CONCLUSION: The results of this study show that new bone regeneration occurs in the maxillary sinus after augmentation with CaS. This enabled successful placement, integration, and loading of dental implants in the posterior maxilla, as only 1 of 40 implants was lost during 1 year of follow-up.

Tissue reactions to subperiosteal onlays of demineralized xenogenous dentin blocks in rats.

OBJECTIVES: This study was undertaken to examine the influence of partial demineralization of xenogenous dentin on bone formation in an osteoconductive environment. MATERIALS AND METHODS: Sixty dentin blocks, 2-3 mm thick and 4 mm in diameter, were prepared from developing teeth of young pigs. Forty blocks were demineralized in 24% ethylenediaminetetraacetic acid (pH 7.0) for 1, 2, 6 or 12 h. Forty adult rats divided into eight groups with five rats in each group were used. A sagittal midcranial incision was made from the occipital to the frontal region. Through a subperiostal dissection, a pocket was created on each side of the skull. One demineralized block was placed on one side, and a non-demineralized block was placed on the contralateral side, or the pocket was left empty as controls. Thus, eight experimental groups with five rats in each were formed. RESULTS: Resorption increased significantly with increasing degree of demineralization while bone formation increased significantly with increasing degree of demineralization, provided inflammation was compensated for. This suggests an important role for inflammation or infection control during the healing period of osteogenic implants to optimize osseous integration in an osteoconductive environment. CONCLUSION: Partial demineralization of xenogenous dentin blocks may provide a method for optimizing the integration of dentin onlays in an osteoconductive environment, thus stabilizing the implant and slowing down replacement resorption.

Histological and histomorphometrical analyses of biopsies harvested 11 years after maxillary sinus floor augmentation with deproteinized bovine and autogenous bone.

OBJECTIVE: The purpose of the present study was to histologically and histomorphometrically evaluate the long-term tissue response to deproteinized bovine bone (DPBB) particles used in association with autogenous bone and to compare particle size after 6 months and 11 years, in the same patients, in order to determine possible resorption. MATERIAL AND METHODS: Twenty consecutive patients (14 women and six men) with a mean age of 62 years (range 48-69 years) with severe atrophy of the posterior maxilla were included in this study. Thirty maxillary sinuses with <5 mm subantral alveolar bone were augmented with a mixture of 80% DPBB and 20% autogenous bone. Eleven years (mean 11.5 years) after augmentation, biopsies were taken from the grafted areas of the 11 patients who volunteered to participate in this new surgical intervention. The following histomorphometrical measurements were performed in these specimens: total bone area in percentage, total area of the DPBB, total area of marrow space, the degree of DPBB-bone contact (percentage of the total surface length for each particle), the length of all DPBB particles and the area of all DPBB particles. The length and the area of the particles were compared with samples harvested from the same patients at 6 months (nine samples) and pristine particles from the manufacturer. RESULTS: The biopsies consisted of 44.7+/-16.9% lamellar bone, 38+/-16.9% marrow space and 17.3+/-13.2% DPBB. The degree of DPBB to bone contact was 61.5+/-34%. There were no statistically significant differences between the length and area of the particles after 11 years compared with those measured after 6 months in the same patients or to pristine particles from the manufacturer. CONCLUSION: DPBB particles were found to be well integrated in lamellar bone, after sinus floor augmentation in humans, showing no significant changes in particle size after 11 years. To cite this article: Mordenfeld A, Hallman M, Johansson CB, Albrektsson T. Histological and histomorphometrical analyses of biopsies harvested 11 years after maxillary sinus floor augmentation with deproteinized bovine and autogenous bone.

Back-scattered electron imaging and elemental analysis of retrieved bone tissue following sinus augmentation with deproteinized bovine bone or biphasic calcium phosphate.

OBJECTIVES: To compare resorption of a synthetic biphasic calcium phosphate (BCP) bone-graft substitute with deproteinized bovine bone (DBB) used for human maxillary sinus augmentation. MATERIALS AND METHODS: Eleven patients underwent bilateral maxillary sinus floor augmentation with DBB in one side and a BCP (40%beta-tricalcium phosphate (beta-TCP) and 60% hydroxyapatite) in the contralateral side. Simultaneously, with the augmentation on each side a microimplant was placed vertically from the top of the alveolar crest penetrating the residual bone and the grafting material. Eight months after initial surgery the microimplants were retrieved with a surrounding bone core. The composition of residual graft material and surrounding bone was analysed by scanning electron microscopy and energy dispersive X-ray spectroscopy. RESULTS: Residual graft material of both types was present as 10-500 mum particles in direct contact with, or completely surrounded by, newly formed bone; smaller particles were also present in non-mineralized tissue. In the case of BCP the bone-graft substitute interface showed evidence of superficial disintegration of particles into individual grains. Median Ca/P ratios (at.%), determined from >200 discreet sites within residual graft particles and adjacent bone, were: DBB: 1.61 (confidence interval [CI] 1.59-1.64); BCP: 1.5 (CI 1.45-1.52); DBB-augmented bone: 1.62 (CI 1.59-1.66); BCP-augmented bone: 1.52 (CI 1.47-1.55); P=0.028 for DBB vs. BCP and DBB- vs. BCP-augmented bone. The reduction in Ca/P ratio for BCP over the healing period is consistent with the dissolution of beta-TCP and reprecipitation on the surface of calcium-deficient hydroxyapatite. CONCLUSION: The beta-TCP component of BCP may be gradually substituted by calcium-deficient hydroxyapatite over the healing period. This process and superficial degranulation of BCP particles may influence the progress of resorption and healing.

Bone replacement following dental trauma prior to implant surgery--status.

Dento-alveolar trauma often leads to a need for reconstruction of the alveolar crest before an implant can be placed. Although autogenous bone grafts is considered the 'gold standard', this may be associated with patient morbidity and graft resorption. Consequently, the use of bone substitutes has increased. Today, a substantial number of biomaterials are available on the market, but only a few are well documented. The user should be aware that these biomaterials have different properties: resorbable or non-resorbable, time of resorption and resorption mechanism. The purpose of this review is to describe the function of various bone substitutes and indications for their use in reconstructive implant surgery and to give an overview of the current situation.

Clinical histology of microimplants placed in two different biomaterials.

PURPOSE: This randomized, controlled study was designed to compare bone formation around microimplants with a sandblasted, acid-etched surface placed at the time of maxillary sinus floor augmentation with a synthetic biphasic calcium phosphate (BCP) or deproteinized bovine bone (DBB). MATERIALS AND METHODS: Nine completely edentulous patients and two partially edentulous patients (six women, five men) with a mean age of 67 years (range, 50 to 79 years) requiring bilateral sinus augmentation were included in the study. The patients were randomized for augmentation with BCP (test) in one side and DBB (control) in the contralateral side. At the time of augmentation, one microimplant on each side was placed vertically from the top of the alveolar crest, penetrating the residual bone and the grafting material. After 8 months of graft healing, at the time of ordinary implant placement, all 22 microimplants were retrieved with a surrounding bone core for histologic analyses. RESULTS: The bone-to-implant contact in the BCP group was 64.6% +/- 9.0%, versus 55.0% +/- 16.0% for the DBB group. The difference was not significant. The corresponding values for the area of newly formed bone in the biopsies were 41.1% +/- 9.8% and 41.6% +/- 14.0% for BCP and DBB, respectively. There were significantly more DBB particles in contact with newly formed bone than BCP particles (87.9 +/- 18.2% versus 53.9 +/- 26.1%; Wilcoxon rank sum test; P = .007). CONCLUSION: In this randomized, controlled clinical trial, new bone formation and bone-to-implant contact around microimplants with a sandblasted, acid-etched surface was found to be equivalent between sinuses augmented with BCP or DBB. Significantly more DBB particles than BCP particles were in contact with newly formed bone, but the clinical relevance of this has yet to be established.

Back-scattered electron imaging and elemental microanalysis of retrieved bone tissue following maxillary sinus floor augmentation with calcium sulphate.

OBJECTIVES: To investigate the presence and composition of residual bone graft substitute material in bone biopsies from the maxillary sinus of human subjects, following augmentation with calcium sulphate (CaS). MATERIAL AND METHODS: Bone cores were harvested from the maxillary sinus of patients who had undergone a sinus lift procedure using CaS G170 granules 4 months after the initial surgery. Samples from seven patients, which contained residual biomaterial particles, were examined by field emission scanning electron microscopy and energy dispersive X-ray spectroscopy was used to determine the composition of the remaining bone graft substitute material. RESULTS: Residual graft material occurred in isolated areas surrounded by bone and consisted of individual particles up to 1 mm in length and smaller spherical granules. On the basis of 187 separate point analyses, the residual material was divided into three categories (A, B and C) consisting of: A, mainly CaS (S/P atomic% ratio > or =2.41); B, a heterogeneous mixture of CaS and calcium phosphate (S/P=0.11-2.4) and C, mainly calcium phosphate (S/P< or =0.11; C), which had a mean Ca : P ratio of 1.63+/-0.2, consistent with Ca-deficient hydroxyapatite. Linescans and elemental maps showed that type C material was present in areas which appeared dense and surrounded, or were adjacent to, more granular CaS-containing material, and also occurred as spherical particles. The latter could be disintegrating calcium phosphate in the final stages of the resorption process. CONCLUSIONS: CaS resorption in the human maxillary sinus is accompanied by CaP precipitation which may contribute to its biocompatibility and rapid replacement by bone.

A new technique for reconstruction of the atrophied narrow alveolar crest in the maxilla using morselized impacted bone allograft and later placement of dental implants.

BACKGROUND: In cases when the alveolar crest is too narrow to host an implant, lateral augmentation is required. The use of autogenous bone blocks harvested from the iliac crest is often demanded. One disadvantage is the associated patient morbidity. PURPOSE: The purpose of this study was to clinically and histologically evaluate the use of morselized impacted bone allograft, a novel technique for reconstruction of the narrow alveolar crest. MATERIALS AND METHODS: Two patients with completely edentulous maxillae and one partially edentulous, with a mean age of 77 years (range 76-79 years) were included in the study. The alveolar crest width was <3 mm without possibility to place any implant. Bone grafts were taken from a bone bank in Gävle Hospital. Bone from the neck of femur heads was milled to produce bone chips. The milled bone was partially defatted by rinsing in 37 degrees C saline solution. After compression of the graft pieces with a size of 15 mm (height), 30 mm (length), and 6 mm (width), they were then fit to adapt to the buccal surface of the atrophied alveolar crest. One piece was placed to the right and one to the left side of the midline. On both sides fibrin glue was used (Tisseel, Baxter AG, Vienna, Austria) to stabilize the graft. After 6 months of graft healing, dental implants were placed, simultaneously biopsies were harvested and in one patient two oxidized microimplants were placed. At the time of abutment connection, microimplants were retrieved with surrounding bone for histology. Fixed screw-retained bridges were fabricated in mean of 7 months after implant surgery. Radiographs were taken before and after implant surgery and after 1 year of loading. RESULTS: Sixteen implants with an oxidized surface were placed (TiUnite, Nobel Biocare AB, Göteborg, Sweden). After 1 year of functional loading, all implants were clinically stable. The marginal bone loss was 1.4 mm (SD 0.3) after 1 year of loading. The histological examination showed resorption and subsequent bone formation on the allograft particles. There were no signs of inflammatory cell infiltration in conjunction with the allograft. The two microimplants showed bone formation directly on the implant surface. CONCLUSIONS: This study shows that morselized impacted bone allograft can be used to increase the width of the atrophied narrow alveolar crest as a good alternative to autogenous bone grafts in elderly patients. The histological examination of biopsies revealed a normal incorporation process and no signs of an immunological reaction. Further studies with larger samples are of important to be able to conclude if equal results can be obtained using morselized impacted bone allograft as for autogenous bone graft.