Long-Term Follow-Up on Soft and Hard Tissue Levels Following Guided Bone Regeneration Treatment in Combination with a Xenogeneic Filling Material: A 5-Year Prospective Clinical Study

Horizontal ridge augmentation in the maxillary aesthetic region using the autogenous circular cortical-lamina anchoring technique: A case series study

AIM

This case series aimed to evaluate the effectiveness of the autologous circular cortical lamina-anchoring (CCA) technique for horizontal bone augmentation in the maxillary aesthetic region.

MATERIALS AND METHODS

A total of 25 patients with 28 implants underwent horizontal bone augmentation using CCA followed by implant placement and crown delivery. The primary outcome measures were alveolar ridge width (ARW) and buccal bone thickness (BBT), whereas the secondary outcome measures included marginal bone loss (MBL), mid-facial mucosal margin loss (MML), clinical assessment of peri-implant and aesthetic parameters, patient-reported outcome measures (PROMs), and implant survival rates.

RESULTS

All 25 patients with 28 implants completed the treatment, no dropouts occurred. After CCA, the mean ARW at 1, 2, and 4 mm below the alveolar crest significantly increased from 2.38 ± 0.48, 2.85 ± 0.51, and 3.21 ± 0.53 mm to 6.80 ± 0.48, 6.99 ± 0.50, and 8.08 ± 0.52 mm, respectively. At the 3-year follow-up, the mean BBT0, BBT2, and BBT4 slightly decreased from 2.51 ± 0.26, 2.63 ± 0.31, and 2.75 ± 0.29 mm to 2.43 ± 0.27, 2.51 ± 0.30, and 2.64 ± 0.28 mm, respectively. Although the overall MBL was <0.15 mm, the results were statistically significant. The mean MML at the 3-year follow-up was 0.02 mm. All implant sites showed acceptable peri-implant and aesthetic outcomes. Incisions healed without complications, and no significant differences in PROMs observed at any time point. The 3-year follow-up showed a 100% implant survival rate.

CONCLUSION

The autologous CCA technique is a useful method for increasing ARW and maintaining BBT in the maxillary aesthetic region.

Horizontal Alveolar Ridge Augmentation with Xenogenic Block Grafts Compared with Autogenous Bone Block Grafts for Implant-retained Rehabilitation: a Systematic Review and Meta-Analysis

Objectives

The objective of the present systematic review and meta-analysis was to test the 0-hypothesis of no difference in implant treatment outcome after horizontal alveolar ridge augmentation with xenogenic block compared with autogenous bone block.

Material and Methods

A literature search was conducted using PubMed, Embase and Cochrane Library databases in combination with a hand-search of relevant journals until 25^th of January 2022. Comparative and non-comparative studies evaluating horizontal alveolar ridge augmentations with xenogenic blocks were included. Quality and risk of bias were evaluated by Cochrane Collaboration's revised tool and Newcastle-Ottawa scale.

Results

Meta-analysis revealed no statistically significant difference in implant survival rate after more than 6 months of functional implant loading (P = 0.71), no difference in alveolar ridge width (P = 0.07) or gain of alveolar ridge width at re-entry (P = 0.13). Non-comparative studies revealed moderate to high short-term implant survival rate and gain in alveolar ridge width, however, complications including dehiscences, graft exposure and graft failure were observed in several studies.

Conclusions

No significant difference could be identified in short-term implant treatment outcome following horizontal alveolar ridge augmentation using xenogenic block compared with autogenous bone block with the limited data available. A high incidence of healing complications and implant failures necessitates further investigation, as well as long-term results on implant survival rate.

Horizontal bone augmentation using two membranes at dehisced implant sites: A randomized clinical study

Background

Placement of dental implant in narrow alveolar ridge is challenging to be treated. GBR procedure is currently most widely used to augment the deficient alveolar ridges and to treat the fenestration and dehiscence around dental implant. Thus, the objectives of the present study were to evaluate as well as compare the clinical performance of collagen membrane and titanium mesh for horizontal bone augmentation at dehisced implant sites.

Methods and material

Total 12 single edentulous implant sites with buccal bone deficiency in 8 subjects were equally divided and treated simultaneously with either of the two membranes and DBBM(Bio-Oss) bone graft. Primary outcome measurements in terms of defect height and defect width were made using calibrated plastic periodontal probe. Re-entry surgery was performed to remeasure augmented site and to remove Ti-mesh at 6th months. Independent paired t-test for the inter-group comparison and student paired t-test for intra-group comparison were performed. The differences were considered to be significant at p ≤ 0.05.

Results

Mean defect fill with respect to height and width was 3.50 ± 0.54 mm (87%) and 2.33 ± 0.51 mm (82%) for collagen membrane and 3.83 ± 0.75 mm (92%) and 2.50 ± 0.54 mm (88%) for Ti-mesh group respectively.

Conclusions

Within the limitation of the study, it was concluded that mean defect height and width after 6 months were statistically significant within the group without significant difference between them, Although defect resolution was better in Ti-mesh.

Horizontal augmentation techniques in the mandible: a systematic review

Purpose

Placement of dental implants has evolved to be an advantageous treatment option for rehabilitation of the fully or partially edentulous mandible. In case of extensive horizontal bone resorption, the bone volume needs to be augmented prior to or during implant placement in order to obtain dental rehabilitation and maximize implant survival and success.

Methods

Our aim was to systematically review the available data on lateral augmentation techniques in the horizontally compromised mandible considering all grafting protocols using xenogeneic, synthetic, or allogeneic material. A computerized and manual literature search was performed for clinical studies (published January 1995 to March 2021).

Results

Eight studies ultimately met the inclusion criteria comprising a total of 276 procedures of xenogeneic, allogeneic, or autogenous bone graft applications in horizontal ridge defects. Particulate materials as well as bone blocks were used as grafts with a mean follow-up of 26.0 months across all included studies. Outcome measures, approaches and materials varied from study to study. A gain of horizontal bone width of the mandible with a mean of 4.8 mm was observed in seven of eight studies. All but one study, reported low bone graft failure rates of 4.4% in average.

Conclusions

Only limited data are available on the impact of different horizontal augmentation strategies in the mandible. The results show outcomes for xenogeneic as well as autologous bone materials for horizontal ridge augmentation of the lower jaw. The use of allogeneic bone-block grafts in combination with resorbable barrier membranes must be re-evaluated. Randomized controlled clinical trials are largely missing.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40729-022-00421-7.

Alveolar Distraction

Alveolar distraction osteogenesis (ADO) has been used for the reconstruction of atrophic alveolus for decades. The advantage of this technique is that it augments the bone and soft tissues together, creating a better alveolar platform for subsequent surgeries and dental rehabilitation. It is especially useful in patients with large and/or complex alveolar clefts for which approximating the alveolar segments reduces the size of the bony cleft and associated fistula. Displacement of the transported segment is the most frequently encountered complication of ADO but can be managed by constructing case-specific distractors.

In Vivo Analysis of the Biocompatibility and Bone Healing Capacity of a Novel Bone Grafting Material Combined with Hyaluronic Acid

The present in vivo study analyses both the inflammatory tissue reactions and the bone healing capacity of a newly developed bone substitute material (BSM) based on xenogeneic bone substitute granules combined with hyaluronate (HY) as a water-binding molecule. The results of the hyaluronate containing bone substitute material (BSM) were compared to a control xenogeneic BSM of the same chemical composition and a sham operation group up to 16 weeks post implantationem. A major focus of the study was to analyze the residual hyaluronate and its effects on the material-dependent healing behavior and the inflammatory tissue responses. The study included 63 male Wistar rats using the calvaria implantation model for 2, 8, and 16 weeks post implantationem. Established and Good Laboratory Practice (GLP)-conforming histological, histopathological, and histomorphometrical analysis methods were conducted. The results showed that the new hyaluronate containing BSM was gradually integrated within newly formed bone up to the end of the study that ended in a condition of complete bone defect healing. Thereby, no differences to the healing capacity of the control BSM were found. However, the bone formation in both groups was continuously significantly higher compared to the sham operation group. Additionally, no differences in the (inflammatory) tissue response that was analyzed via qualitative and (semi-) quantitative methods were found. Interestingly, no differences were found between the numbers of pro- and anti-inflammatory macrophages between the three study groups over the entire course of the study. No signs of the HY as a water-binding part of the BSM were histologically detectable at any of the study time points, altogether the results of the present study show that HY allows for an optimal material-associated bone tissue healing comparable to the control xenogeneic BSM. The added HY seems to be degraded within a very short time period of less than 2 weeks so that the remaining BSM granules allow for a gradual osteoconductive bone regeneration. Additionally, no differences between the inflammatory tissue reactions in both material groups and the sham operation group were found. Thus, the new hyaluronate containing xenogeneic BSM and also the control BSM have been shown to be fully biocompatible without any differences regarding bone regeneration.

Clinical and volumetric outcomes after vertical ridge augmentation using computer-aided-design/computer-aided manufacturing (CAD/CAM) customized titanium meshes: a pilot study

Background

One of the most recent innovations in bone augmentation surgery is represented by computer-aided-design/computer-aided-manufacturing (CAD/CAM) customized titanium meshes, which can be used to restore vertical bone defects before implant-prosthetic rehabilitations. The aim of this study was to evaluate the effectiveness/reliability of this technique in a consecutive series of cases.

Methods

Ten patients in need of bone augmentation before implant therapy were treated using CAD/CAM customized titanium meshes. A digital workflow was adopted to design virtual meshes on 3D bone models. Then, Direct Metal Laser Sintering (DMLS) technology was used to produce the titanium meshes, and vertical ridge augmentation was performed according to an established surgical protocol. Surgical complications, healing complications, vertical bone gain (VBG), planned bone volume (PBV), lacking bone volume (LBV), regenerated bone volume (RBV), average regeneration rate (RR) and implant success rate were evaluated.

Results

All augmented sites were successfully restored with definitive implant-supported fixed partial dentures. Measurements showed an average VBG of 4.5 ± 1.8 mm at surgical re-entry. Surgical and healing complications occurred in 30% and 10% of cases, respectively. Mean values of PBV, LBV, and RBV were 984, 92, and 892 mm³, respectively. The average RR achieved was 89%. All 26 implants were successfully in function after 1 year of follow-up.

Conclusions

The results of this study suggest that the bone augmentation by means of DMLS custom-made titanium meshes can be considered a reliable and effective technique in restoring vertical bone defects.

Treatment of peri-implant soft tissue defects: a narrative review

Soft tissue defects around dental implants, such as papilla or volume loss, peri-implant recession and alterations of the ridge color and/or texture, lead to esthetic and functional complaints. Treatments of these defects in implants are more demanding than in teeth because peri-implant tissue exhibits different anatomical and histological characteristics. This narrative review discusses the proposed treatments for soft tissue defects around implants in the current literature. Several clinical and pre-clinical studies addressed methods to augment the quantity of the peri-implant keratinized mucosa. Autogenous grafts performed better than soft tissue substitutes in the treatment of soft tissue defects, but there is no clinical consensus on the more appropriate donor area for connective tissue grafts. Treatment for facial volume loss, alterations on the mucosa color or texture and shallow peri-implant recessions are more predictable than deep recessions and sites that present loss of papilla. Correction of peri-implant soft tissue defects may be challenging, especially in areas that exhibit larger defects and interproximal loss. Therefore, the regeneration of soft and hard tissues during implant treatment is important to prevent the occurrence of these alterations.

Improvement of bone repair with l-PRF and bovine bone in calvaria of rats. histometric and immunohistochemical study

OBJECTIVES

The effect of leucocyte- and platelet-rich fibrin (L-PRF), associated with DBBM (deproteinized bovine bone mineral; Bio-Oss®) was investigated and compared with autogenous bone graft as a standard material for filling bone defects.

MATERIAL AND METHODS

A defect of 5 mm in diameter was performed in 40 calvaria of rats. The animals were divided into 5 groups and received blood clot (CO), autogenous bone (AUT), DBBM (BIO), L-PRF, or DBBM associated with L-PRF (BIO-LPRF). After 4 and 8 weeks, bone regeneration was assessed by histometric and immunohistochemical analyses.

RESULTS

The highest mean percentage of bone formation found at 4 and 8 weeks was observed for the BIO-L-PRF group (54.0% ± 2.8 and 63.6% ± 2.2). The lowest mean percentage at 4 and 8 weeks was observed for the CO group (16.7% ± 2.5 and 20.5% ± 1.0). There was statistical similarity among the AUT, BIO, and L-PRF groups. The expressions OC, RUNX 2, and VEGF showed a favorable aspect in the formation of new bone for BIO-L-PRF. VEGF was the marker with the highest expression because it was related to the initial healing process, promoting the migration and proliferation of endothelial cells in the region of the defect. Even after weeks, VEGF maintained a moderate expression.

CONCLUSIONS

The association of L-PRF with DBBM improved bone repair when these biomaterials were inserted into the defects of the calvaria of rats.

CLINICAL RELEVANCE

This reinforces the good performance of bovine bone and L-PRF as filler materials, especially when associated.

Long term follow-up of titanium implants installed in block-grafted areas: A systematic review

BACKGROUND

An enduring clinical question concerns the outcome (ie, success) of implants placed in areas grafted with block-grafts.

OBJECTIVE

To undertake a systematic review of the literature on the long term results (≥5 years) of implants placed in maxillofacial areas grafted with any type of osseous block-grafts in two-stage surgeries. Further, the review addresses how available success criteria were used within the studies.

MATERIALS AND METHODS

The MEDLINE (PubMed) and EMBASE bibliographic databases were searched up to March 2017 for studies evaluating the long term results of implants placed in grafted areas. The search strategy was restricted to English language publications using combined terms which referred to the treatment method (implants placed in areas grafted with bone blocks), and follow-up characteristics (≥5 years and assessment of at least one parameter related to implant success criteria). To qualify for inclusion, studies should present outcome measurements indicating the success (or at least the survival) of the implants.

RESULTS

The search strategy yielded 17 studies, which were included in this systematic review. These studies presented survival rates ranging from 88.7% (after 15 years follow-up) to 98.7% (after 5 years follow-up). Five studies presented data based on predefined success criteria with success rates ranging from 86.8% to 100%. In these studies, the term "success" was often not properly defined.

CONCLUSION

The long term survival (≥5 years) of implants placed into block-grafted areas in two-stage surgeries was not lower than 75%, while success rates ranged from 86.8% to 100%. Although it was possible to identify published success criteria for implant follow-up, there is no broad consensus on how to report implant success in a consistent manner.

Hydroxyapatite from Fish for Bone Tissue Engineering: A Promising Approach

Natural or synthetic hydroxyapatite (HA) has been frequently used as implant materials for orthopaedic and dental applications, showing excellent bioactivity, adequate mechanical rigidity and structure, osteoconductivity and angiogenic properties, no toxicity, and absence of inflammatory or antigenic reactions. HA can be easily synthesized or extracted from natural sources, such as bovine bone. However, the manufacturing costs to obtain HA are high, restricting the therapy. Herein, much effort has been paid for obtaning alternative natural sources for HA. The potential of HA extracted from skeleton of animals has been investigated. The aim of this review is to exploit the potential of HA derived from fish to fulfill biological activities for bone tissue engineering. In particular, HA from fish is easy to be manufactured regarding the majority of protocols that are based on the calcination method. Furthermore, the composition and structure of HA from fish were evaluated; the biomaterial showed good biocompatibility as a result of non-cytotoxicity and handling properties, demonstrating advantages in comparison with synthetic ones. Interestingly, another huge benefit brought by HA from bone fish is its positive effect for environment since this technique considerably reduces waste. Certainly, the process of transforming fish into HA is an environmentally friendly process and stands as a good chance for reducing costs of treatment in bone repair or replacement with little impact into the environment.

Lateral ridge augmentation with Bio-Oss alone or Bio-Oss mixed with particulate autogenous bone graft: a systematic review

The objective of this systematic review was to test the hypothesis of no difference in implant treatment outcomes when using Bio-Oss alone or Bio-Oss mixed with particulate autogenous bone grafts for lateral ridge augmentation. A search of the MEDLINE, Cochrane Library, and Embase databases in combination with a hand-search of relevant journals was conducted. Human studies published in English from 1 January 1990 to 1 May 2016 were included. The search provided 337 titles and six studies fulfilled the inclusion criteria. Considerable variation prevented a meta-analysis from being performed. The two treatment modalities have never been compared within the same study. Non-comparative studies demonstrated a 3-year implant survival of 96% with 50% Bio-Oss mixed with 50% autogenous bone graft. Moreover, Bio-Oss alone or Bio-Oss mixed with autogenous bone graft seems to increase the amount of newly formed bone as well as the width of the alveolar process. Within the limitations of this systematic review, lateral ridge augmentation with Bio-Oss alone or in combination with autogenous bone graft seems to induce newly formed bone and increase the width of the alveolar process, with high short-term implant survival. However, long-term studies comparing the two treatment modalities are needed before final conclusions can be drawn.

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.

Guided bone regeneration using chitosan-collagen membranes in dog dehiscence-type defect model

PURPOSE

The purpose of the present study was to compare a newly developed chitosan-collagen membrane (CCM) with a standard collagen membrane (SCM) regarding their effects on guided bone regeneration.

MATERIALS AND METHODS

The right mandibular premolars and first molar were extracted from 12 beagle dogs. Four months later, acute buccal dehiscence-type defects (4 × 3 mm in height and width) were surgically created after implant site preparation. The defects were randomly assigned to 4 different groups: CCM-1 (weight ratio of chitosan to collagen of 40:1), CCM-2 (weight ratio of chitosan to collagen of 20:1), SCM, and vehicle control. The dogs were sacrificed after 4, 8, and 12 weeks of healing for radiographic examination, histologic observation, and histometric analysis.

RESULTS

The membrane-treated sites showed more bone formation than the control sites, although no statistically significant differences were found between the membrane-treated sites and the control sites for new bone-to-implant contact and new bone-filled area at any point. At 8 weeks, the new bone height for the membrane-treated sites was significantly greater statistically than that of the untreated group (P < .05). At 12 weeks, the CCM-1 group showed significantly greater new bone height (1.91 ± 0.25 mm) than the untreated group (1.20 ± 0.34 mm; P < .05). However, the CCMs did not show any statistically significant differences compared with the SCMs for any assessed parameter.

CONCLUSIONS

The results of the present study have shown that the developed CCMs can enhance bone regeneration and could be a candidate for use in guided bone regeneration.

Recent developments of functional scaffolds for craniomaxillofacial bone tissue engineering applications

Autogenous bone grafting remains a gold standard for the reconstruction critical-sized bone defects in the craniomaxillofacial region. Nevertheless, this graft procedure has several disadvantages such as restricted availability, donor-site morbidity, and limitations in regard to fully restoring the complicated three-dimensional structures in the craniomaxillofacial bone. The ultimate goal of craniomaxillofacial bone reconstruction is the regeneration of the physiological bone that simultaneously fulfills both morphological and functional restorations. Developments of tissue engineering in the last two decades have brought such a goal closer to reality. In bone tissue engineering, the scaffolds are fundamental, elemental and mesenchymal stem cells/osteoprogenitor cells and bioactive factors. A variety of scaffolds have been developed and used as spacemakers, biodegradable bone substitutes for transplanting to the new bone, matrices of drug delivery system, or supporting structures enhancing adhesion, proliferation, and matrix production of seeded cells according to the circumstances of the bone defects. However, scaffolds to be clinically completely satisfied have not been developed yet. Development of more functional scaffolds is required to be applied widely to cranio-maxillofacial bone defects. This paper reviews recent trends of scaffolds for crania-maxillofacial bone tissue engineering, including our studies.

Le Fort I osteotomies using Bio-Oss® collagen to promote bony union: a prospective clinical split-mouth study

The purpose of this study was to evaluate whether a bone substitute can be used to promote bony union in patients undergoing maxillary advancement after Le Fort l osteotomy. Nine patients were treated bilaterally with Le Fort I osteotomies and maxillary advancements of 5mm or less. In each patient, one gap was grafted with the bone substitute Bio-Oss(®) Collagen (BOC). The contralateral site was left empty and served as control. After 6 months there were still empty gaps in the control sites of three patients, while in the grafted sites all gaps were completely filled with bone. The histomorphometric analysis performed with biopsies from the region of the original gap showed a similar amount of new bone in both groups, however, in the test group the mean overall amount of the mineralized fraction was higher compared to the control group (test site 65.0±6.2%, control site 38.9±32.6%). The bone substitute seemed to be a suitable material to promote bony union in Le Fort I osteotomies. Further studies are needed to analyse whether this technique is efficient in preventing relapse and promoting bony union in larger advancements.

Horizontal alveolar distraction osteogenesis for dental implant: long-term results

OBJECTIVES

The aim of the present study was to present the results of patients followed for at least 3 years who underwent horizontal distraction osteogenesis DO and a final implant prosthesis.

MATERIAL AND METHODS

A total of 13 sites in 12 patients (three men, nine women; mean age 45.4 years, range 21-63 years) who presented with severe horizontal atrophy of a partially edentulous maxilla or mandible were treated using horizontal DO. The horizontal distraction device was set on the transport bone which was osteotomized as bone splitting method and fixed to the segment using microscrews.

RESULTS

The median of latency period was 9 days (range: 7-17); the median of amount of device activation was 5.6 mm (range: 4.4-9.6); the median of distraction period was 14 days (range: 8-24); and the median of consolidation period, from the end of activation until implant placement, was 13 weeks (range: 11-20). The median of actual gain in bone width at the end of the consolidation period was 3.6 mm (range: 1.1-5.6). A total of 35 implants were inserted in the augmented area with primary implant stability. The median of follow-up from the start of prosthetic loading was 5.4 years. Consequently, the implant survival and success rates were 100% and 94.2%, respectively.

CONCLUSION

This article reports the long-term results of horizontal alveolar DO using a mesh device for patients with an atrophic alveolar region. Our results confirm that this technique is a predictable and effective regenerative procedure for implant preprosthetic treatment in patients with severe horizontal atrophy of the alveolar ridge.

Volumetric difference evaluation of registered three-dimensional pre-operative and post-operative CT dental data

OBJECTIVE

The purpose of this study is to propose a complete methodology for automatically registering three-dimensional (3D) pre-operative and post-operative CT scan dental volumes as well as to provide a toolset for quantifying and evaluating their volumetric differences.

METHODS

The proposed methodology was applied to cone beam CT (CBCT) data from 20 patients in order to assess the volume of augmented bone in the alveolar region. In each case, the pre-operative and post-operative data were registered using a 3D affine-based scheme. The performance of the 3D registration algorithm was evaluated by measuring the average distance between the edges of the registered sets. The differences between the registered sets were assessed through 3D subtraction radiography. The volume of the differences was finally evaluated by defining regions of interest in each slice of the subtracted 3D data and by combining all respective slices to model the desired volume of interest. The effectiveness of the algorithm was verified by applying it to several reference standard-shaped objects with known volumes.

RESULTS

Satisfactory alignment was achieved as a low average offset of 1.483 ± 1.558 mm was recorded between the edges of the registered sets. Moreover, the estimated volumes closely matched the volumes of the reference objects used for verification, as the recorded volume differences were less than 0.4 mm(3) in all cases.

CONCLUSION

The proposed method allows for automatic registration of 3D CBCT data sets and the volumetric assessment of their differences in particular areas of interest. The proposed approach provides accurate volumetric measurements in three dimensions, requiring minimal user interaction.

Timing of implant placement and augmentation with bone replacement material: clinical assessment at 8 and 16 months

PURPOSE

The purpose of this study is to evaluate implants placed at different times of bone augmentation.

MATERIALS AND METHODS

Four implants were placed in seven dogs: one at a 6-month bovine mineral grafted site (6-month Bio-Oss® grafted site [6mBio]), one at a grafted membrane-protected simultaneously augmented (Fresh Bio-Oss® grafted site [FrBio]) site, one at a clotted (nongrafted clotted membrane-protected site [Clot]) membrane-protected site, and one at a pristine (nongrafted uncovered site [Cont]) site. Implants were exposed after 6 months. The same protocol was repeated on the contralateral side, at a delay of 8 months. Peri-implant care was performed throughout the hygienic phase (2 and 10 months, respectively) every 48 to 72 hours. Probing depth and bleeding on probing were recorded. Implant stability was determined by a Periotest® (Medizintechnik Gulden, Modautal, Germany). Statistical analysis was conducted using analysis of variance with repeated measures.

RESULTS

Average probing depth at the simultaneously grafted sites was 2.21 mm and 2.03 mm at 8 and 16 months, respectively. At the 6-month grafted sites, it was 1.96 mm and 1.57 mm. At the Clot sites, it was 2.68 mm and 2.07 mm, and 2.21 mm and 1.82 mm at the Cont sites, respectively. The average bleeding on probing was 0.50 and 0.42 at the FrBio sites, and 0.35 and 0.07 at the 6mBio sites during the respective periods. At the Clot sites, it was 0.50 and 0.28, and at the Cont sites, 0.43 and 0.21, respectively. Probing depth significantly reduced over the time at 6mBio, Clot, and Cont sites (p < .03). Average implant stability score at the FrBio sites was -0.24 and -0.27, and -0.50 and -0.46 at the 6mBio sites, at 8 and 16 months, respectively. At the Clot sites, it was -0.35 and -0.46. Cont sites averaged -0.37 at both periods. Implant stability was significantly higher (p < .005) comparing 6mBio over FrBio, 6mBio over Cont, and Clot over FrBio sites.

CONCLUSIONS

Immediate and delayed augmentations are safe modes. Probing depth and bleeding indices gradually improved along time. Implant stability was higher at the delayed mode.