Guided bone regeneration with barrier membranes--a clinical and radiographic follow-up study after 24 months

Short-term and long-term success and survival rates of implants supporting single-unit and multiunit fixed prostheses: A systematic review and meta-analysis

STATEMENT OF PROBLEM

Whether placing implants to replace each missing tooth or using implant-supported fixed partial dentures provides better outcomes is unclear.

PURPOSE

The purpose of this systematic review and meta-analysis was to assess the success and survival rates of implants supporting single-unit and multiunit fixed prostheses by using conventional protocols for placement and loading in short- and long-term follow-ups.

MATERIAL AND METHODS

An electronic search was conducted in PubMed, Scopus, and Web of Science for studies published up to March 17, 2022. Comparative studies that reported the success or survival rates of both single-unit and splinted multiunit prostheses were considered for qualitative and quantitative analyses.

RESULTS

A total of 68 publications comprising 11 271 implants were included. Compared with the single prostheses, the splinted multiunit group showed no significant differences in implant success rates in the short-term (risk difference=-0.004; 95% confidence interval (CI)=-0.033 to 0.025; P=.780) and long-term (risk difference=0.003; 95% confidence interval (CI)=-0.029 to 0.034; P=.874) follow-ups. Significant statistical differences were also not found in terms of the survival rates of the 2 groups (short-term risk difference=-0.004; 95% CI=-0.031 to 0.023; P=.779, long-term risk difference=-0.002; 95% CI=-0.029 to 0.025; P=.887).

CONCLUSIONS

Implants supporting single-unit or splinted multiunit prostheses seem to be a predictable treatment in terms of survival and success over short and long periods. Nonetheless, it seems that cantilever and nonsplinted multiunit prostheses should be used with more caution.

Hard Tissue Volume Stability Effect beyond the Bony Envelope of a Three-Dimensional Preformed Titanium Mesh with Two Different Collagen Barrier Membranes on Peri-Implant Dehiscence Defects in the Anterior Maxilla: A Randomized Clinical Trial

This single-blinded, randomized, controlled study aimed to clinically and radiographically evaluate hard tissue volume stability beyond the bony envelope using three-dimensional preformed titanium mesh (3D-PFTM) for peri-implant dehiscence defects in the anterior maxilla. A total of 28 patients who wished to undergo implant surgery combined with guided bone regeneration (GBR) after extraction of a single maxillary anterior tooth were randomly assigned to two groups depending on the type of collagen membrane used, additionally with the 3D-PFTM—test (n = 14, cross-linked collagen membrane; CCM) and control (n = 14, non-cross-linked collagen membrane; NCCM) groups. Each implant was evaluated radiographically using CBCT at baseline, immediately after surgery, and at 6 months postoperatively. The relative position and distances from the bony envelope to the outlines of the augmented ridge were further determined immediately after GBR and 6 months after healing. At the platform level, the mean horizontal hard tissue gain (HG) at all the sites was 2.35 ± 0.68 mm at 6 months postoperatively. The mean HG rate was 84.25% ± 14.19% in the CCM group and 82.56% ± 13.04% in the NCCM group, but the difference was not significant between the groups. In all cases, HG was maintained beyond the bony envelope even after 6 months of GBR. This study suggests that 3D-PFTM should be considered a valuable option for GBR for peri-implant dehiscence defects in the anterior maxilla. In addition, 3D-PFTM may confer predictable hard tissue volume stability even after the healing period of hard tissue augmented outside the bony envelope by GBR.

Exposure of Barriers Used in GBR: Rate, Timing, Management, And Its Effect on Grafted Bone. A Retrospective Analysis

The purpose of this study is to compare exposure rate of three different barrier types after a guided-bone regenerationprocedure, as well as to compare the percentage grafted bone dimensional loss with and without exposed barriers. Patient records from September 2007 to May 2015 were reviewed to identify subjects that had received bone graft and then implant placement procedure after the graft is completely healed. The subjects were divided into 3 groups: 1) resorbable barrier 2) non-resorbable barrier, and 3) titanium-mesh barrier. Incidences of barrier exposure were recorded.  Cone-beam computed tomography images before treatment (T0), right after grafting (T1), and after healing (T2) were used to determine percentage grafted bone dimensional loss (%) and quantitative grafted bone remained (mm 2 ). Three cross-sectioned areas, at 1mm apart, of preplanned implant positions at the grafted site were measured on cone-beam computed tomography to calculate for grafted bone remained and grafted bone dimensional change. The exposure rate of all guided bone regeneration was 36.9%. Exposure rate of resorbable barrier (23.3%) is significantly lower than Titanium mesh (68.9%) and Non-resorbable (72.7%) (Chi-Square, P < .001).  The result from this study revealed that barrier types have significant effect on exposure rate. There was also a significant different in grafted bone dimensional loss in sites with barrier exposure (58.3%) and sites with no barrier exposure (44.1%) during the healing period (Mann-Whitney U, P = .008).

Retrospective Analysis of the Effect of Three-Dimensional Preformed Titanium Mesh on Peri-Implant Non-Contained Horizontal Defects in 100 Consecutive Cases

This study aimed to clinically and radiographically evaluate the results of guided bone regeneration (GBR) using three-dimensional preformed titanium mesh (3-D-PFTM) for non-contained horizontal defects in 100 consecutive cases. This study involved 100 patients (129 implants) with peri-implant non-contained horizontal defects. The patients were divided into three groups: 3-D-PFTM alone (Group 1), 3-D-PFTM plus cross-linked collagen membrane (Group 2), and 3-D-PFTM plus non-cross-linked collagen membrane (Group 3). Each implant was evaluated radiographically using CBCT at baseline and 6 months postoperatively. At the platform level, the mean horizontal hard tissue gain of all the sites was 3.1 ± 1.3 mm at 6 months postoperatively. The mean rate of mesh exposure was 11.8% in Group 1, 4.2% in Group 2, and 5.0% in Group 3. The mean hard tissue gain rate was 71.0 ± 23.0% in group 1, 84.2 ± 21.5% in group 2, and 84.0 ± 22.9% in group 3. Groups 2 and 3 showed significantly higher hard tissue gain rates than group 1. However, there was no significant difference between the rates in groups 2 and 3. Within the limitations of this study, 3-D-PFTM should be considered as a valuable option for GBR for peri-implant non-contained horizontal defects. The use of an additional resorbable collagen membrane provides additional advantages.

Distance of insertion points in a mattress suture from the wound margin for ideal primary closure in alveolar mucosa: an in vitro experimental study

Purpose

This study was conducted to determine how the distance of the near insertion points in a vertical mattress suture from the wound margin influences the pattern of primary closure in an in vitro experimental model.

Methods

Pairs of 180 porcine gingival and alveolar mucosa samples were harvested from 90 pig jaws and fixed to a specially designed model. A vertical mattress suture was performed with the near insertion point at 3 different distances from the wound margin (1-, 3-, and 5-mm) on both the gingival and mucosal samples (6 groups; n=30 for each group). The margin discrepancy and the presence of epithelium between the wound margins were measured on histologic slides.

Results

The margin discrepancy decreased significantly as the near insertion point became closer to the wound margin both in mucosal tissue (0.241±0.169 mm, 0.945±0.497 mm, and 1.306±0.773 mm for the 1-, 3-, and 5-mm groups, respectively) and in gingival tissue (0.373±0.304 mm, 0.698±0.431 mm, and 0.713±0.691 mm, respectively). The frequency of complications of wound margin adaptation reduced as the distance of the near insertion point from the wound margin decreased both in the mucosal and gingival tissues.

Conclusions

Placing the near insertion point close to the wound margin enhances the precision of wound margin approximation/adaptation using a vertical mattress suture.

Histology of augmented autogenous bone covered by a platelet-rich fibrin membrane or deproteinized bovine bone mineral and a collagen membrane: A pilot randomized controlled trial

OBJECTIVES

This study aimed to evaluate histologic and histomorphometric bone characteristics with a focus on vitality after lateral alveolar ridge augmentation using an autogenous bone graft as a block covered by either a platelet-rich fibrin (PRF) membrane (test group) or a standard procedure involving coverage of the bone block with a deproteinized bovine bone mineral and a resorbable collagen membrane (control group).

MATERIAL AND METHODS

A total of 27 (test = 14, control = 13) partially edentulous patients with indication for bone block augmentation before implant installation were included. For analyses, a biopsy of augmented bone was retrieved six months after bone grafting.

RESULTS

Histologic evaluation of augmented bone revealed a predominance of non-vital bone toward the periosteum and few localized areas of vital bone in the center of the graft in both groups. In contrast, augmented bone toward the native bone demonstrated extensive bone remodeling in both groups. Histomorphometric analyses demonstrated a mean of 14% vital bone, 80% non-vital bone, 5% soft tissue, and 1% blood vessels in the test group. In the control group, the corresponding shares were 14% vital bone, 63% non-vital bone, 22% soft tissue, and 1% blood vessels. We observed no significant differences between the groups (p > .05).

CONCLUSION

In conclusion, a comparable low bone vitality of augmented bone was observed in the PRF and in the control group. Consequently, the present study could not verify the potential beneficial effect of a PRF membrane on bone vitality of an autogenous bone graft used as a block.

Comparison of Different Bone Filling Materials and Resorbable Membranes by Means of Micro-Tomography. A Preliminary Study in Rabbits

The purpose of this work was to evaluate the behavior of different membranes and bone filling materials used to fill critical defects in rabbit calvaria. Four defects were prepared in the cranial calvaria of female rabbits. They were randomly divided into three subgroups according to the type of barrier membrane to be used. Four animals carried cross-linked bovine collagen membranes (Mem-Lok, Bio-Horizons, Birmingham, AL, USA)), four human fascia lata membranes (Tissue, Inbiomed SA, Córdoba, Argentina) and four human chorioamniotic membranes (Tissue. Inbiomed SA, Córdoba, Argentina). The defects were filled with the deproteinized bovine bone particulate Bio­Oss® (Geistlich­Pharma AG, Wolhusen, Switzerland), with particulate human hydroxyapatite MinerOss® (Bio-Horizons, Birmingham, AL, USA), with particulate dental material (Tissue Bank Foundation, Inbiomed S.A., Córdoba, Argentina), and the last one was left without the addition of filler material. In the first group of four specimens, a resorbable cross-linked bovine collagen membrane was placed over the skull and defects, without additional fixing. In the second group, a human fascia lata membrane was placed, without additional fixing. In the third group, a human chorioamniotic membrane was placed, without additional fixing. The animals were sacrificed at 4 and 8 weeks. The highest percentages of relative radiological density (average) were recorded considering the amnio-chorionic membranes (83.63%) followed by collagen (81.44%) and finally the fascia lata membranes (80.63%), but the differences were not statistically significant (p > 0.05). The sites grafted with a decellularized tooth (96.83%) and Bio­Oss (88.42%), recorded the highest percentages of radiological density but did not differ significantly from each other (subset 2). The three membranes used did not show statistical differences between them, in any of the two time periods used. There were statistical differences between the filling materials evidencing the presence of a large quantity of calcified material in the defects treated with particulate tooth and deproteinized bovine bone and while smaller amounts of calcified material were registered in the case of defects treated with human hydroxyapatite and those that were not treated.

Soft-tissue esthetic outcome of single implants: Immediate placement in fresh extraction sockets versus conventional placement in healed sockets

Background:

Immediate implant placement has advantages such as requiring fewer surgical procedures and decreased treatment time; however, unpredictable soft- and hard-tissue outcome is a problem. This study aimed to compare the soft-tissue esthetic outcome of single implants placed in fresh extraction sockets versus those placed in healed sockets.

Materials and Methods:

This cross-sectional, retrospective study was performed on 42 patients who received single implants. Twenty-two patients with a mean age of 40.14 years received immediate implants while 18 patients with a mean age of 43.40 years were subjected to conventional (delayed) implant placement. The mean follow-up time was 14.42 ± 8.37 months and 18.25 ± 7.10 months in the immediate and conventional groups, respectively. Outcome assessments included clinical and radiographic examinations. The esthetic outcome was objectively rated using the pink esthetic score (PES).

Results:

All implants fulfilled the success criteria. The mean PES was 8.54 ± 1.26 and 8.10 ± 1.65 in the immediate and conventional groups, respectively. This difference was not statistically significant (P = 0.329). The two PES parameters, namely, the facial mucosa curvature and facial mucosa level had the highest percentage of complete score.

Conclusions:

Immediate and conventional single implant treatments yielded comparable esthetic outcomes.

The effect of strontium ranelate on the healing of a fractured ulna with bone gap in rabbit

BACKGROUND

Fracture healing in bone gap is one of the major challenges encountered in Orthopedic Surgery. At present, the treatment includes bone graft, employing either internal or external fixation which has a significant impact on the patient, family and even society. New drugs are emerging in the markets such as anabolic bone-forming agents including teriparatide and strontium ranelate to stimulate bone growth. Based on the mechanism of their actions, we embarked on a study on the healing of a fractured ulna with bone gap in a rabbit model. We segregated ten rabbits into two groups: five rabbits in the test group and five rabbits in the control group. We created a 5 mm bone gap in the ulna bone, removing the periosteum as well. Rabbits in the test group received 450 mg/kg of strontium ranelate via oral administration, daily, for six weeks. The x-rays, CT scans and blood tests were performed every two weeks. At the end of six weeks, the rabbits were sacrificed, and the radius and ulna bones harvested for histopathological examination.

RESULTS

Based on the x-rays and CT scans, fracture healing or bone formation was observed to be faster in the control group. From the x-ray findings, 80 % of the fracture united and by CT scan, 60 % of the fracture united in the control group at the end of the six-week study. None of the fractures united in the test group. However, the histopathology report showed that a callus of different stages was being formed in both groups, consisting of 80 % of bone. The serum levels of osteocalcin and alkaline phosphatase initially remained similar up to three weeks and changed slightly at the end of six weeks.

CONCLUSIONS

We conclude that the strontium effect begins slowly, and while it may not interfere with bone cell proliferation it may interfere in the mineralization and delay the acute stage of fracture healing. We recommend that a larger sample size and a longer duration of the study period be implemented to confirm our finding.

Radiological and Biological Assessment of Immediately Restored Anterior Maxillary Implants Combined with GBR and Free Connective Tissue Graft

OBJECTIVES

Radiologic and biologic assessment of immediately restored Implants combined with guided bone regeneration (GBR) and free connective tissue graft.

METHODS

1-4 year retrospective study involving 34 patients treated with maxillary immediately restored anterior single-implants. Soft tissue dimensions, radiographic bone loss, and biological and prosthetic complications were assessed.

RESULTS

During the mean follow up period of 29 months the study group presented a mean mesial bone loss of 1.10 ± 0.39 mm (range: 0.5-2.4 mm), and mean distal bone loss of 1.19 ± 0.41 mm (range: 0.4-2.1 mm). Mean periimplant probing depth of 3.49 mm (SD ± 1.06) and 2.35 (SD ± 0.52) for the contralateral tooth (highly significant p < 0.001). Bleeding on probing was present in 29.4% of the examined implant supported crown sites and 10.4% of the contralateral teeth (p < 0.001).

CONCLUSIONS

Anterior maxillary single-tooth replacement, using GBR and connective tissue graft according to the concept of immediate implant placement, and non-functional restoration is an accepted treatment modality achieving favorable peri-implant soft tissue condition.

Are there specific indications for the different alveolar bone augmentation procedures for implant placement? A systematic review

Bone resorption following tooth loss often interferes with dental implant placement in a desired position, and requires additional bone augmentation procedures. Many techniques have been described to augment and reconstruct alveolar ridge width and height. The aim of this study was to systemically review whether there is evidence to provide indications for the various bone augmentation procedures based on defect dimension and type. An electronic search of the Medline database and Cochrane library, complemented by a manual search, was performed. Inclusion criteria for partial edentulism were: clinical trials on bone augmentation procedures in preparation or at the time of implant placement, reporting preoperative and postoperative dimensions of the ridge. For edentulous patients, studies were included when providing the data on ridge and defect description, or the amount of augmentation achieved. The search yielded 53 publications for partially edentulous patients and 15 publications for edentulous patients. The literature provides evidence that dehiscence and fenestrations can be treated successfully with guided bone regeneration (GBR) at the time of implant placement (mean implant survival rate (MISR) 92.2%, mean complication rate (MCR) 4.99%). In partially edentulous ridges, when a horizontal defect is present, procedures such as staged GBR (MISR 100%, MCR 11.9%), bone block grafts (MISR 98.4%, MCR 6.3%), and ridge expansion/splitting (MISR 97.4%, MCR 6.8%) have proved to be effective. Vertical defects can be treated with simultaneous and staged GBR (MISR 98.9%, MCR 13.1% and MISR 100%, MCR 6.95%, respectively), bone block grafts (MISR 96.3%, MCR 8.1%), and distraction osteogenesis (MISR 98.2%, MCR 22.4%). In edentulous patients, there is evidence that bone block grafts can be used (MISR 87.75%), and that Le Fort I osteotomies can be applied (MISR 87.9%), but associated with a high complication rate. The objective of extracting specific indications for each procedure could not be fully achieved due to the heterogeneity of the studies available. Further studies on bone augmentation procedures should report precise preoperative and postoperative measurements to enable a more exact analysis of the augmentation procedure, as well as to provide the clinician with the rationale for choosing the most indicated surgical approach.

Immediate versus delayed positioning of dental implants in guided bone regeneration or onlay graft regenerated areas: a systematic review

The aim of this study was to compare success rates in immediate and delayed dental implant placement following guided bone regeneration or onlay bone block ridge augmentation. A systematic review of all studies on this topic was performed. For inclusion, studies had to involve at least five patients, report specific success criteria, and have a minimum follow-up period of 6 months. Studies reporting only the survival rate of implants were excluded. From 287 studies identified, 79 were screened and 13 were included in the analysis. Six studies provided data on simultaneous (immediate) positioning of implants, five studies on delayed positioning, and two studies provided data on both of these approaches. Success rates for implants placed using a simultaneous approach ranged from 61.5% to 100%; success rates for implants placed using a staged approach ranged from 75% to 98%. Even though the current review revealed that there are not many studies reporting data relevant to the analyzed topic, the data obtained suggest that the delayed positioning of implants should be considered more predictable than the immediate positioning. Studies presenting a control group and adopting standardized success criteria are required, and data from this review must be considered indicative.

Success rate of dental implants inserted in horizontal and vertical guided bone regenerated areas: a systematic review

This study assessed the success rate of implants placed in horizontal and vertical guided bone regenerated areas. A systematic review was carried out of all prospective and retrospective studies, involving at least five consecutively treated patients, that analysed the success rate of implants placed simultaneously or as second surgery following ridge augmentation by means of a guided bone regeneration (GBR) technique. Studies reporting only the survival rate of implants and studies with a post-loading follow up less than 6 months were excluded. From 323 potentially relevant studies, 32 full text publications were screened and 8 were identified as fulfilling the inclusion criteria. The success rate of implants placed in GBR augmented ridges ranged from 61.5% to 100%; all studies, apart from three, reported a success rate higher than 90% (range 90-100%). The data obtained demonstrated that GBR is a predictable technique that allows the placement of implants in atrophic areas. Despite that, studies with well-defined implant success criteria after a longer follow-up are required.

A randomized-controlled clinical trial evaluating clinical and radiological outcomes after 3 and 5 years of dental implants placed in bone regenerated by means of GBR techniques with or without the addition of BMP-2

OBJECTIVE

The aim of this randomized-controlled clinical trial was to evaluate the long-term outcome of implants placed in bone augmented with a xenogenic bone substitute material and a collagen membrane with or without the addition of recombinant human bone morphogenetic protein-2 (rhBMP-2).

MATERIAL AND METHODS

Eleven patients received a total of 34 implants placed into sites exhibiting lateral bone defects. In a split mouth design, the defects were randomly treated with the graft material and the collagen membrane either with (test) or without (control) rhBMP-2. The patients were examined 3 and 5 years after insertion of the prosthetic restoration. Student's paired t-test was performed to detect differences between the two groups.

RESULTS

The survival rate at 3 and 5 years was 100% for both groups. The peri-implant soft tissues were stable and healthy without any difference between the two groups. The prosthetic reevaluation demonstrated four loose prosthetic screws during the first 3 years and seven ceramic chippings after 3 and 5 years. The mean distance between the first bone to implant contact to implant abutment junction at 3 years was 1.37 mm (test), 1.22 mm (control), and 1.38 mm (test), and 1.23 mm (control) at 5 years. The difference of <0.2 mm between test and control implants was not statistically significant. The mean change of the marginal bone level between baseline and 5 years ranged from -0.07 mm (mesial, test), -0.11 mm (distal, test), -0.03 mm (mesial, control), to +0.13 mm (distal, control). No statistically significant differences were observed between test and control sites.

CONCLUSION

Implants placed in bone augmented with and without rhBMP-2 revealed excellent clinical and radiological outcomes after 3 and 5 years.

Autograft containment in posterolateral spine fusion

BACKGROUND CONTEXT

Pseudoarthrosis rates in lumbar intertransverse fusion remain high. Compression and displacement of the developing fusion mass by the paraspinal musculature may be a contributory factor. Biocontainment devices have been clinically used in the skull and mandible to guide bone regeneration. The role of a mechanical device in containing graft material in the developing posterolateral lumbar spine fusion is unclear.

PURPOSE

To determine the benefits of using a bioabsorbable graft-containment device for lumbar intertransverse fusion, and to evaluate the biocompatibility of this implant by histological analysis of the host tissue reaction.

STUDY DESIGN

A rabbit intertransverse spine fusion model was used to evaluate a bioabsorbable graft-containment implant. Study and control groups were compared with regard to the rate, volume, and quality of fusion, as well as host tissue reaction to the graft and implant.

METHODS

Fourteen adult male New Zealand White rabbits underwent bilateral posterolateral intertransverse spine arthrodesis at L3-L4. The control group (n=7) received autograft alone, and the study group received autografts placed in open meshed hemicylinders fashioned from LactoSorb sheets (LactoSorb; Biomet Orthopedics Inc., Warsaw, IN). Spines were harvested at 6 weeks and imaged. Radiographs and computed tomography (CT) images were used to calculate the rate, area, and volume of fusion mass. Sections were fixed and stained with hematoxylin-eosin and Mallory trichrome for histological analysis of fusion and host tissue response. The Mann-Whitney nonparametric statistical test was used for the radiographic and CT qualitative assessments. The CT volume quantitation was analyzed using the Student t test. A p value of <.05 was used to assign statistical significance.

RESULTS

The fusion rates on radiographs and CT imaging did not show a significant difference (p>.05) between the biocontainment and control groups. The volume of fusion revealed a significant increase with biocontainment (mean+/-standard error; total left+right fusion sides=2.88+/-0.30 cc) compared with controls (2.12+/-0.15 cc) (p<.05). Histology revealed no difference in the maturity or the quality of the fusion mass between the two groups. Inflammatory response around the developing fusion mass and muscle necrosis were slightly increased in the study group. The LactoSorb biocontainment material led to variable inflammatory reaction, with some areas showing little or no response and other showing an inflammatory response with fibrous connective tissue, lymphocyte infiltration, and focal foreign body giant cell reaction.

CONCLUSIONS

The incidence of fusion was similar with or without a containment device for onlay bone graft. A significant increase in the volume of the fusion suggests that a biocontainment device does play a role in protecting the developing fusion mass from the mechanical effects of the paraspinal musculature. The clinical use of this device cannot be justified at this time, and further studies will determine whether this increase in fusion volume will translate into a better incidence and volume of fusion in primate and human models.

Oral rehabilitation using Camlog�screw?cylinder implants with a particle-blasted and acid-etched microstructured surface. Results from a prospective study with special consideration of short implants

OBJECTIVES

The purpose of the present clinical study was to report on the clinical performance of screw-cylinder implants with special consideration of the survival rate of short implants.

MATERIAL AND METHODS

In this prospective study with consecutive patient recruitment, Camlog screw-cylinder implants with a particle-blasted and acid-etched microstructured surface and a triple-cam tube-in-tube implant-abutment connection have been used only. Two groups of implants were evaluated: implants of 9 and 11 mm in length were considered short, those of 13 and 16 mm were considered long. Besides clinical and radiographic parameters, data of complications, patients' subjective evaluation of treatment outcome, general medical history and smoking habits were recorded.

RESULTS

Three hundred and thirty-three Camlog screw-cylinder implants were inserted in 133 patients. One hundred and twenty-nine patients were available for follow-up, representing 325 implants. The median observation period was 33 months (Q(25%) 26; Q(75%) 38). After a maximum observation period of 55 months, the Kaplan-Meier-survival analysis revealed no significant difference between the mean survival probabilities of 98.3% (n=59, patient-related) of short implants, and of 95.7% of long implants (n=70, patient-related) (P=0.162). No significant difference was found between implant survival rates considering maxilla (98.7%) and mandible (98.2%). A stratified analysis of short implants revealed a significant influence of premature cover screw exposures (P=0.02) and smoking (P=0.008) on implant survival. These influences were not found significant for long implants.

CONCLUSIONS

The prognosis of short Camlog implants is comparable with that of long implants. Therefore, their clinical use instead of performance of sophisticated vertical augmentation procedures before installation of long implants might be considered as alternative treatment option. In smokers, the use of short implants should be considered cautiously, however. The risk of premature cover screw exposure should be minimized.

Augmentation procedures for the rehabilitation of deficient edentulous ridges with oral implants

OBJECTIVES

To analyze publications related to augmentation procedures and to evaluate the success of different surgical techniques for ridge reconstruction and the survival/success rates of implants placed in the augmented areas.

MATERIAL AND METHODS

Clinical investigations published in English involving at least 5 patients and with a minimum follow-up of 6 months were included. The following procedures were considered: a) Guided bone regeneration (GBR); 2) Onlay bone grafts; 3) Inlay grafts; 4) Bone splitting for ridge expansion (RE); 5) Distraction osteogenesis (DO); and 6) Revascularized flaps. Success rates of augmentation procedures and related morbidity, as well as survival and success rates of implants placed in the augmented sites were analyzed.

RESULTS

Success rates of surgical procedures ranged from 60% to 100% for GBR, from 92% to 100% for onlay bone grafts, from 98% to 100% for ridge expansion techniques, from 96,7% to 100% for DO, and was 87.5% for revascularized flaps, whereas survival rates of implants ranged from 92% to 100% for GBR, from 60% to 100% for onlay bone grafts, from 91% to 97.3% for RE, from 90.4% to 100% for DO, and, finally, was 88.2% for revascularized flaps.

CONCLUSION

On the basis of available data it was shown that it was difficult to demonstrate that a particular surgical procedure offered better outcome as compared to another. The main limit encountered in this review has been the overall poor methodological quality of the published articles. Therefore larger well-designed long term trials are needed.

Effects of Bioactive Glass on Bone Augmentation Within a Titanium Cap in Rabbit Parietal Bone

BACKGROUND

The condition of alveolar bone influences the success and subsequent esthetics of implant treatment. This study investigated the early effects of bioactive glass (BG) on bone augmentation within a hemispherical titanium cap in rabbit parietal bone.

METHODS

Twelve adult male Japanese white rabbits were used. One titanium cap (test site) was packed with BG in a collagen gel, and the other (control site) was packed with the collagen gel alone. After 1 and 3 months, animals were euthanized, and the experimental area was examined using fluorescence and light microscopy.

RESULTS

Newly generated bone was observed at 1 and 3 months of healing. Although bone was also generated without BG, newly mineralized bone was generated sooner with BG present for guided bone augmentation than without BG. At 1 and 3 months, the BG was not bioabsorbed completely, and some particles remained.

CONCLUSION

New bone is generated at an early stage of bone formation using BG for bone augmentation.

The effects of guided tissue regeneration (GTR) on modified Le Fort I osteotomy healing in rabbits

Osteogenesis following surgery depends on the osteoblasts at the wound site. Fibrous nonunions may be the result of differential and rapid migration of fibroblasts compared to osteoblasts into the wound. The present study was designed to test this hypothesis through the use of guided tissue regeneration (GTR) in a rabbit model. Bilateral, Le Fort I osteotomies (n=20) were produced in the maxillae of 10 New Zealand White rabbits. The segments were advanced 6mm and rigidly fixed using microplates and screws. One side was covered with a resorbable collagen membrane or left uncovered. Rabbits were followed for four weeks with radiographs and the maxillae were harvested for histology. Cephalometry revealed that membrane-covered defects had significantly (P<0.01) reduced defect area (by approximately 70%) compared to uncovered defects. Histologically, membrane-covered defects showed more organized osteogenesis and less fibrous tissue than uncovered defects. Histomorphometry revealed that membrane covered defects had significantly (P<0.05) reduced defect areas (by approximately 20%) compared to uncovered defects. While findings suggest that GTR can facilitate osseous wound healing in Le Fort I osteotomies, results also caution against relying exclusively on two-dimensional radiography to assess bony wound healing in lieu of three-dimensional imaging and evaluations.

Prosthetically driven Implant Placement. How to achieve the appropriate implant site development

Dental implants are established alternatives for replacing missing teeth. Tooth loss for different reasons may leads to alveolar resorption. Shortage of bone can prevent proper positioning of dental implants according to prosthetic needs and treatment planning, unless the volume of hard and soft tissues is increased before implantation. In the esthetic area it is essential not only to achieve well-anchored implants but also sufficient soft and hard tissue in order to obtain natural looking result. This article will present several treatment modalities to augment the soft and hard tissues in order to obtain proper insertion of implants according to prosthetic needs and patient satisfaction.

Localized Ridge Augmentation/Preservation.A Systematic Review

BACKGROUND

Osseointegrated implants have been documented as efficacious, however, their placement may be contraindicated in some patients due to insufficient bone volume. Techniques such as guided bone regeneration (GBR), immediate implantation, and distraction osteogenesis (DO) have been utilized as ridge enhancement therapies.

RATIONALE

This systematic review evaluates dental implant survival rates in patients treated with ridge augmentation or preservation techniques.

FOCUSED QUESTION

In patients requiring dental implant placement, what is the effect of localized ridge preservation versus implant placement without augmentation on implant survival and adverse effects?

SEARCH PROTOCOL

MEDLINE and Cochrane Oral Health Group Specialized Trial Register were searched. Hand searches were performed on Clinical Oral Implants Research, International Journal of Oral and Maxillofacial Implants, International Journal of Periodontics and Restorative Dentistry, Journal of Clinical Periodontology, Journal of Periodontology, and Journal of Periodontal Research. All searches were performed for articles published through April 2002.

SELECTION CRITERIA

Publications reporting survival rate of dental implants following ridge therapy were included in the analysis. Reports describing techniques were excluded.

DATA COLLECTION AND ANALYSIS

Due to the absence of controlled studies, a meta-analysis was not performed. Descriptive statistics are used to report the data.

MAIN RESULTS

1. A total of 18 studies were included: 13 reporting on guided bone regeneration (GBR, 1,741 patients) and 5 on distraction osteogenesis (DO, 92 patients). 2. There is a high level of predictable implant survival in sites treated by GBR or DO. 3. These survival rates are similar to those of implants placed in native bone. REVIEWERS' INTERPRETATIONS: Survival rates were similar for both GBR and DO implants. These survival rates were similar to implants placed in native bone.

A systematic review of the survival of implants in bone sites augmented with barrier membranes (guided bone regeneration) in partially edentulous patients

The aim of the present systematic review was to assess the survival of implants in regenerated bone applying the method of guided bone regeneration (GBR) compared with the survival of implants in non-regenerated bone. Studies to be included in this review needed to provide at least 12-month results following prosthetic reconstruction of titanium implants in bone regenerated by GBR with or without membrane supporting materials. The outcome measures were implant survival described as presence of implant, implant success (according to the criteria in the respective study), absence of clinical implant mobility, absence of implant fracture, absence of progressive peri-implant crestal bone loss as assessed on radiographs without clinical signs of peri-implant infection, absence of peri-implant infection with suppuration. A MEDLINE search and a hand search of relevant scientific journals were conducted including studies from the year 1990 to May 2001. A total of 11 studies could be identified fulfilling the inclusion criteria. All studies except two had the characteristics of case series or cross-sectional surveys. The two different studies had both test and control implants included in their analysis and qualified as controlled clinical trials. Cumulative success or survival rates, respectively, for implants in regenerated bone ranged from 100% after 5 years to 79.4% after 5 years of function. Regarding survival data, no significant differences were found in the controlled clinical trials between implants in regenerated compared to implants in non-regenerated bone. Within the limits of this systematic review characterized by second and third levels of evidence, the following conclusions can be drawn: The survival rate of implants placed into sites with regenerated/augmented bone using barrier membranes varied between 79% and 100% with the majority of studies indicating more than 90% after at least one year of function. The survival rates obtained in the present systematic review are similar to those generally reported for implants placed conventionally into sites without the need for bone augmentation.

Immediate loading of single-tooth implants in the anterior maxilla. Preliminary results after one year

According to the standard protocol, a load-free healing period is one of the most emphasized requirements for implant integration. Recent studies have encouraged a progressive shortening of the healing period for single-tooth implants and immediate loading has been proposed for the aesthetic zone in the maxilla. The present study evaluated clinical outcomes of immediately loaded FRIALIT-2 Synchro implants 12 months after placement in the maxillary incisal region. In the course of our investigation, nine patients have been treated following an immediate loading protocol. The stepped-screw type implants were inserted with an increasing torque up to 45 Ncm, thus measuring the primary stability of the implants. All implants were immediately restored with unsplinted acrylic resin provisional crowns and the patients provided with occlusal splints. Regular controls were performed at monthly intervals, intraoral radiographs were taken directly after implant placement, 6 and 12 months post insertion. The survival rate, clinical stability (Periotest) and radiographic coronal bone defects (CBD) were evaluated at delivery of the definitive superstructures (CBD 6) and 6 months later (CBD 12). Twelve FRIALIT-2 Synchro stepped screws of 3.8, 4.5 and 5.5 mm diameter and 13 and 15 mm length were placed in the incisal maxillary region. The median Periotest value 6 months post insertion was -2 with a minimum of -5 and a maximum of +2. The mean coronal bone level changes (CBD) at 6 and 12 months were 0.45 and 0.75 mm. No implant failed up to 12 months after insertion, resulting in a 100% survival rate. The presented results showed promising data for immediately loaded single-tooth implants in the anterior maxilla. Periotest values were within the range published for submerged implants. The radiographic coronal bone resorption after 6 and 12 months was even less than evaluated for implants placed in a standard two-stage procedure. It is evident that successful immediate loading protocols require a careful and strict patient selection aimed at achieving the best primary stability and avoiding any excessive functional or non-functional loading. Additional research needs to be done to provide data in situations where problems of poor bone quality, multiple implants or augmentation procedures must be overcome.

Evaluation of implants placed with barrier membranes. A restrospective follow-up study up to five years

This follow-up study evaluated clinical and radiographic parameters of dental implants placed in combination with guided bone regeneration with barrier membranes. All implants functioned well up to 60 months after insertion. Forty-one patients, with a total of 72 augmented implants, who participated in a regular maintenance protocol, were investigated. Annual Periotest values (median value, - 3) revealed stable periimplant conditions and sustained osseointegration. At 6 months and annually thereafter up to five years, the radiographic evaluation yielded mean bone losses of 0.8, 1.25, 1.39, 1.42, 1.42 and 1.39 mm, respectively, with a range from 0 to 3.5 mm. No implant failures or losses were recorded. The results demonstrated stable periimplant conditions up to five years after membrane-protected osseous regeneration, with no significant differences in the radiographic bone level in regard to region, jaw or bone graft. Premature membrane exposure resulted in a significantly higher crestal bone loss up to 24 months. The newly formed bone appeared to be able to withstand functional loading for up to 60 months in a predictable manner.

Effects of fixation type and guided tissue regeneration on maxillary osteotomy healing in rabbits

PURPOSE

The development of fibrous nonunions after orthognathic surgery is thought to result from an interaction of biomechanical stress and the differential and more rapid migration of fibroblasts (compared with osteoblasts) into the wound site during healing. The present study was designed to test this hypothesis through the manipulation of guided tissue regeneration and osteotomy fixation techniques in an experimental rabbit model.

MATERIALS AND METHODS

Bilateral critical size (4 mm) defects (n = 24) were produced in the maxillae of 12 adult New Zealand white rabbits. The maxillary segments were rigidly or nonrigidly fixed using bone microplates and screws or osteosynthetic wires. The defects were then covered with a resorbable collagen membrane or left uncovered. The rabbits were followed for 4 weeks with the use of serial dorsoventral and lateral oblique cephalographs, and the maxillae were then harvested for histologic analyses.

RESULTS

Radiographic and histomorphometric analyses revealed that rigidly fixed defects, covered with membrane, showed the most rapid and organized new bone formation. The rigidly fixed defects with the membrane averaged approximately 40% more new bone in the osteotomy site compared with the rigidly fixed defects with no membrane. Nonrigidly fixed defects with no membrane showed an ingrowth of fibroblasts and fibrous nonunions.

CONCLUSIONS

These experimental results suggest that an interaction between the decreased fibrous tissue ingrowth through guided tissue regeneration and osteotomy segment stability from rigid fixation prevented postoperative fibrous nonunions and facilitated new bone regeneration and osteotomy site healing in this rabbit model.

A survey of clinical members of the Association of Dental Implantology in the United Kingdom. Part III. The use of augmentation techniques in dental implant surgery

The aims of the survey were to: (1) determine the use of the staged and simultaneous augmentation techniques; (2) determine trends in the use of barrier membranes; (3) establish the perceived reliability of techniques used to monitor implants that have undergone simultaneous augmentation; and (4) assess the use of biopsy techniques to confirm the histologic outcome of bone augmentation. One hundred seventy-two respondents replied to this section of the survey and indicated that the "staged" and "simultaneous" augmentation techniques were used in roughly equal numbers during 1997, and a wide range of complications was reported with the latter. The majority used barrier membranes to correct defects of between 5 and 10 mm3, and resorbable membranes were preferred. With regard to clinical techniques used to monitor augmented implants, these were mainly considered to be "adequate" or "poor." Tissue biopsy was recognized as an important tool for determining the outcome of augmentation procedures but was rarely used. The use of resorbable membranes is likely to increase. The diagnostic tools currently used to monitor augmented implants are considered to have limited reliability, and they should be evaluated by prospective, comparative studies. More widespread use of biopsy techniques might help establish an evidence base for the histologic outcome of augmentation materials and techniques.

Mathematical analysis of projection errors in "paralleling technique" with respect to implant geometry

"Standardized" radiographs acquired in paralleling technique serve for monitoring of marginal bone levels around endosseous implants. Under clinical conditions, parallel adjustment of the film to the implant is beset with great difficulties. A mathematical model matching clinical conditions was developed to evaluate projection geometry within an interval of clinically relevant angulations (+/- 10 degrees from parallel position). Radiographs of two implants (Frialit 2, Friadent AG, Mannheim, Germany; Implant No. 1: 3.8 mm, length 10 mm; Implant No. 2: 6.5 mm, length 13 mm) were separately produced per angulation (2 degrees increments) at one focus-object distance (FO=322.9 mm). Implant images were repeatedly measured along their midline/vertical edge, local magnification (MF) was calculated and the values were compared to the computed ones. Projected dimensions of the implants were calculated for a second distance (232.3 mm). The experimentally acquired data were in agreement with the mathematical calculation. MF calculated for assessment along the vertical edge varied less (+/-1.94% from mean value) than along the midline (+/-2.74%), with a range of 1.037-1.068 (FO=322.9 mm) and 1.061-1.099 (FO=232.3 mm) for implant No.1, and 1.060-1.101 (FO=232.3 mm) and 1.037-1.069 (FO=322.9 mm) for Implant No. 2. Magnification revealed a mean variation of 4%. Radiographic evaluation of periimplant bone level should not exceed a precision of 0.5 mm, when parallelism between film and implant is not guaranteed and FO is less than 380 mm.

The effect of membrane exposure on the outcome of regenerative procedures in humans: a meta-analysis

BACKGROUND

The significance of early membrane exposure on the regenerative outcome in guided tissue regeneration (GTR) and guided bone regeneration (GBR) procedures is somewhat controversial. Several clinical trials have shown better response when the membranes remained submerged (S) compared to those that have become exposed (E) during healing. Other studies have failed to show any such difference. Small sample size and/or large standard deviation of the changes might account for these discrepancies. The purpose of this meta-analysis is to critically combine the existing data in order to provide meaningful information based on a large database.

METHODS

Studies of GTR in Class II furcation and intrabony defects (IBD), together with GBR around dental implants, where the membrane became exposed during the postoperative period, were combined to form 3 separate databases. A meta-analysis was employed to compare the 2 subgroups (E versus S) in each of the databases. First, weighted mean changes and weighted standard errors were calculated for each subgroup. Next, an individual study P value was calculated (1-tailed Student t test); finally, a combined Fisher's P statistic (with 5% significance level) was calculated from the individual P values.

RESULTS

Five studies with a total of 101 sites were included in the furcation database; 43 of these sites became exposed. Mean horizontal attachment level (AL) gain for the S sites (3.72 +/- 0.15 mm) was slightly greater than that of the E sites (3.06 +/- 0.15 mm; P = 0.030257). For the intrabony group, there were 309 sites in 5 studies: of these, 142 sites became exposed. Mean gain in vertical AL was 4.22 +/- 0.15 mm and 4.69 +/- 0.13 mm for the E and S group, respectively (P = 0.011415). The GBR group included 60 sites in 2 studies: new bone formation in the 24 S sites (3.01 +/- 0.38 mm) was 6-fold greater compared with the 36 E sites (0.56 +/- 0.45 mm). These differences were also statistically significant (P = 0.001875).

CONCLUSIONS

Membrane exposure during healing had a major negative effect on GBR around dental implants but only a minimal effect on GTR around natural teeth.

Dental implants in periodontal therapy

Over the past 30 years, research has validated the success of osseointegrated implants as a viable alternative to fixed or removable prosthetic restorations. Periodontists are extensively trained in surgical procedures to treat and maintain patients with edentulous and partially edentulous arches. They also have a primary role in treatment planning and maintenance therapy. Thus, periodontists routinely integrate endosseous implants into periodontal therapy. This paper was prepared by the Research, Science and Therapy Committee of the American Academy of Periodontology and is intended to inform the dental profession regarding the utility of endosseous dental implants in the treatment of full and partial edentulism.