Single-staged implant placement using the bone ring technique with and without membrane placement: Micro-CT analysis in a preclinical in vivo study

Ultrasound-based jawbone surface quality evaluation after alveolar ridge preservation

BACKGROUND

Bone readiness for implant placement is typically evaluated by bone quality/density on 2-dimensional radiographs and cone beam computed tomography at an arbitrary time between 3 and 6 months after tooth extraction and alveolar ridge preservation (ARP). The aim of this study is to investigate if high-frequency ultrasound (US) can classify bone readiness in humans, using micro-CT as a reference standard to obtain bone mineral density (BMD) and bone volume fraction (BVTV) of healed sockets receiving ARP in humans.

METHODS

A total of 27 bone cores were harvested during the implant surgery from 24 patients who received prior extraction with ARP. US images were taken immediately before the implant surgery at a site co-registered with the tissue biopsy collection location, made possible with a specially designed guide, and then classified into 3 tiers using B-mode image criteria (1) favorable, (2) questionable, and (3) unfavorable. Bone mineral density (hydroxyapatite) and BVTV were obtained from micro-CT as the gold standard.

RESULTS

Hydroxyapatite and BVTV were evaluated within the projected US slice plane and thresholded to favorable (>2200 mg/cm3; >0.45 mm3/mm3), questionable (1500-2200 mg/cm3; 0.4-0.45 mm3/mm3), and unfavorable (<1500 mg/cm3; <0.4 mm3/mm3). The present US B-mode classification inversely scales with BMD. Regression analysis showed a significant relation between US classification and BMD as well as BVTV. T-test analysis demonstrated a significant correlation between US reader scores and the gold standard. When comparing Tier 1 with the combination of Tier 2 and 3, US achieved a significant group differentiation relative to mean BMD (p = 0.004, true positive 66.7%, false positive 0%, true negative 100%, false negative 33.3%, specificity 100%, sensitivity 66.7%, receiver operating characteristics area under the curve 0.86). Similar results were found between US-derived tiers and BVTV.

CONCLUSION

Preliminary data suggest US could classify jawbone surface quality that correlates with BMD/BVTV and serve as the basis for future development of US-based socket healing evaluation after ARP.

Efficacy of bone ring grafts for the reconstruction of alveolar ridge deficiencies: a systematic review. Part II: animal trials

Background

Bone ring (BR) grafts have been introduced to reconstruct alveolar ridge defects with simultaneous implant placement, but their clinical effectiveness remains undetermined. The aim of the current systematic review was to critically appraise evidence from animal studies regarding the effectiveness of BR grafts in alveolar ridge reconstruction and their variations under different surgical protocols.

Methods

Electronic retrieval of six databases (MEDLINE, Embase, Cochrane Library, ScienceDirect, Web of Science, and Scopus) and citation search until 11 October 2023, for animal studies on bone augmentation employing BR grafts. The outcome variables were total bone area (BA), bone volume (BV), bone-implant contact (BIC), and histology. The protocol was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and prospectively registered with PROSPERO (CRD42023453949).

Results

Ten studies were included in the qualitative analysis according to the screening criteria. Two studies demonstrated favorable bone remodeling and osseointegration of the BR with both the implant and pristine bone. A comparative study between autogenous BRs and allogenic BRs reported a higher percentage of BA and BIC at 4 months of healing, but conflicting data were observed at 8 months. Another study indicated a significant advantage of autogenous BRs over bovine and biphasic ceramic BRs in terms of BA and BIC after 5 weeks. Three studies found that using collagen membranes did not significantly affect BA, BV, or BIC when used simultaneously with autogenous BRs during implant placement. Two studies evaluated one-stage and two-stage implant placement in conjunction with BR grafts, revealing similar levels of BA, BV, and BIC except for differences in total treatment time. Furthermore, one study found that the use of mucogingival junction incision and split-thickness flap significantly reduced the incidence of wound dehiscence compared with conventional incision and flap.

Conclusions

Vertical bone augmentation surgery utilizing BR grafts with one-stage implant placement yielded histological and histomorphometric outcomes comparable to those achieved with two-stage implant placement or the additional application of collagen membrane.

Autogenous bone ring augmentation around single tooth implantation in the esthetic zone: A retrospective case series study with 2-3 years of follow-up

Background

/purpose: Bone ring technique (BRT) is an effective method to reconstruct alveolar bone defects with simultaneous implant placement. This study aimed to evaluate the efficacy of the BRT in single maxillary anterior tooth implantation and its esthetic outcomes over 2-3 years of follow-up.

Materials and methods

Fifteen patients with single maxillary incisor loss received autogenous BRT with simultaneous implant placement. The vertical/horizontal bone gain, remaining vertical bone height (RVBH), remaining buccal bone width (RBBW), and vertical/horizontal bone resorption around implant over 2-3 years of follow-up were measured by using cone-beam computed tomography. Esthetic results including white esthetic score (WES), pink esthetic score (PES), and papilla index (PI) were evaluated by clinical recorded photographs.

Results

All implants showed evidence of osseointegration, and the mean vertical and horizontal bone gain of 14 sites was 5.55 ± 0.87 mm and 4.73 ± 0.70 mm, respectively. During 2-3 years of follow-up, all mean values of RBBW were more than 2 mm. Main vertical bone loss appeared within 4 months after surgery and the RVBH value decreased as the follow-up duration continued. Maximum buccal bone thickness resorption mostly appeared in the middle level of the implant during the primary two follow-up periods (P < 0.05). Esthetic results showed that the mean WES/PES was higher than 17, and more than half cases demonstrated relatively high PI (3 points) throughout the follow-up.

Conclusion

BRT could achieve excellent bone augmentation effect and can offer predictable esthetic outcomes for single tooth implant restoration in the esthetic zone.

Sequential osseointegration of a novel implant system based on 3D printing in comparison with conventional titanium implants

OBJECTIVES

To evaluate the sequential osseointegration of a novel titanium implant system based on a 3D printing technology in comparison with conventional titanium implants.

MATERIAL AND METHODS

Two novel titanium implants based on 3D printing were tested in the mandible of eight Beagle dogs. As a control, two different commercially available titanium implants were used. The implants were staged to accommodate healing periods of 2 and 6 weeks. The primary outcome variable was bone-to-implant contact (BIC) in non-decalcified tissue sections and micro-CT analysis.

RESULTS

Histomorphometrically, the proportions of tissues adjacent to the implant surfaces were similar for all implants, whereas the BIC percentage of new mineralized bone was greater for the control implants after both 2 and 6 weeks (p < .05). Micro-CT analysis revealed increasing osseous volume and BIC from 2 to 6 weeks. In contrast to the histomorphometry, the BIC evaluation with the micro-CT data revealed a significantly higher BIC for the two test implants compared with controls (p < .001). The analysis of the total implant surface area disclosed a value that was approximately double as high for the test compared to the control implants.

CONCLUSIONS

The novel titanium implant system based on 3D printing yielded values for osseointegration that were adequate and satisfactory. The higher percentage of new mineralized bone in the control implants is explained by the fact of a completely different three-dimensional surface area.

Bone Quantification Around Chitosan-Coated Titanium Dental Implants: A Preliminary Study by Micro-CT Analysis in Jaw of a Canine Model

Surface treatments of Ti in the dental implant industry are performed with the aim of in-creasing its bioactivity and osseointegration capacity. Chitosan (Cht) is a polysaccharide that has been proposed as a promising biomaterial in tissue engineering and bone regeneration, due to its ability to stimulate the recruitment and adhesion of osteogenic progenitor cells. The aim of our preliminary study was to evaluate, by micro-computed tomography (micro-CT), the osseointegration and bone formation around Cht-coated implants and to compare them with conventional surface-etched implants (SLA type). Four im-plants (8.5 mm length × 3.5 mm Ø) per hemiarch, were inserted into the jaws of five dogs, divided into two groups: chitosan-coated implant group (ChtG) and control group (CG). Twelve weeks after surgery, euthanasia was performed, and sectioned bone blocks were obtained and scanned by micro-CT and two bone parameters were measured: bone in contact with the implant surface (BCIS) and peri-implant bone area (PIBA). For BCIS and PIBA statistically significant values were obtained for the ChtG group with respect to CG (p = 0.005; p = 0.014 and p < 0.001 and p = 0.002, respectively). The results, despite the limitations, demonstrated the usefulness of chitosan coatings. However, studies with larger sample sizes and adequate experimental models would be necessary to confirm the results.

Impact of simultaneous placement of implant and block bone graft substitute: an in vivo peri-implant defect model

Background

Insufficient bone volume around an implant is a common obstacle when dental implant treatment is considered. Limited vertical or horizontal bone dimensions may lead to exposed implant threads following placement or a gap between the bone and implant. This is often addressed by bone augmentation procedures prior to or at the time of implant placement. This study evaluated bone healing when a synthetic TiO₂ block scaffold was placed in circumferential peri-implant defects with buccal fenestrations.

Methods

The mandibular premolars were extracted and the alveolar bone left to heal for 4 weeks prior to implant placement in six minipigs. Two cylindrical defects were created in each hemi-mandible and were subsequent to implant placement allocated to treatment with either TiO₂ scaffold or sham in a split mouth design. After 12 weeks of healing time, the samples were harvested. Microcomputed tomography (MicroCT) was used to investigate defect fill and integrity of the block scaffold. Distances from implant to bone in vertical and horizontal directions, percentage of bone to implant contact and defect fill were analysed by histology.

Results

MicroCT analysis demonstrated no differences between the groups for defect fill. Three of twelve scaffolds were partly fractured. At the buccal sites, histomorphometric analysis demonstrated higher bone fraction, higher percentage bone to implant contact and shorter distance from implant top to bone 0.5 mm lateral to implant surface in sham group as compared to the TiO₂ group.

Conclusions

This study demonstrated less bone formation with the use of TiO₂ scaffold block in combination with implant placement in cylindrical defects with buccal bone fenestrations, as compared to sham sites.

Autogenous bone ring for vertical bone augmentation procedure with simultaneous implant placement: A systematic review of histologic and histomorphometric outcomes in animal studies

STATEMENT OF PROBLEM

The performance of the autogenous bone ring (ABR) technique used for the vertical bone augmentation procedure has not yet been determined.

PURPOSE

The purpose of this systematic review was to investigate whether the ABR technique for the vertical bone augmentation procedure with simultaneous implant placement enhances the histologic and histomorphometric outcomes in surgically created bone defects in animal models.

MATERIAL AND METHODS

An electronic search of 3 databases, Medline/PubMed, Science Direct, Lilacs, and a manual search of a reference list of relevant studies were performed. Only animal studies regarding vertical bone augmentation by using the ABR technique with simultaneous implant placement in surgically created bone defects were included in the review. The SYstematic Review Center for Laboratory Animal Experimentation tool was used to determine the risk of bias assessment, and the quality of included studies was assessed by using the Animal Research: Reporting in Vivo Experiments guidelines.

RESULTS

Five studies were included in the qualitative analysis based on the inclusion and exclusion criteria. One study comparing the ABR technique with the bovine and biphasic ring reported a high percentage of bone area and bone implant contact of the ABR at 5 weeks of osseointegration. Similar histologic findings were reported in another study at 4 months of healing, but contrasting data were reported at 8 months. Another study reported an increase in the percentage of bone area and bone implant contact of the ABR technique from 3 months to 6 months of osseointegration. Two studies reported an increase in the percentage of bone area, and 1 study reported a decrease in the mean of bone implant contact, both with simultaneous and staged implant procedures.

CONCLUSION

Based on the limited available studies, the use of the ABR technique for the vertical bone augmentation procedure with simultaneous implant placement presented optimal histologic and histomorphometric outcomes in surgically created bone defects in animal models. However, the results of the current review are not sufficiently robust to support the use of the ABR technique for vertical bone augmentation in humans.

Pre-Clinical Models in Implant Dentistry: Past, Present, Future

Biomedical research seeks to generate experimental results for translation to clinical settings. In order to improve the transition from bench to bedside, researchers must draw justifiable conclusions based on data from an appropriate model. Animal testing, as a prerequisite to human clinical exposure, is performed in a range of species, from laboratory mice to larger animals (such as dogs or non-human primates). Minipigs appear to be the animal of choice for studying bone surgery around intraoral dental implants. Dog models, well-known in the field of dental implant research, tend now to be used for studies conducted under compromised oral conditions (biofilm). Regarding small animal models, research studies mostly use rodents, with interest in rabbit models declining. Mouse models remain a reference for genetic studies. On the other hand, over the last decade, scientific advances and government guidelines have led to the replacement, reduction, and refinement of the use of all animal models in dental implant research. In new development strategies, some in vivo experiments are being progressively replaced by in vitro or biomaterial approaches. In this review, we summarize the key information on the animal models currently available for dental implant research and highlight (i) the pros and cons of each type, (ii) new levels of decisional procedures regarding study objectives, and (iii) the outlook for animal research, discussing possible non-animal options.

Horizontal bone augmentation and simultaneous implant placement using xenogeneic bone rings technique: a retrospective clinical study

This study evaluated the use of bone ring technique with xenogeneic bone grafts in treating horizontal alveolar bone defects. In total, 11 patients in need of horizontal bone augmentation treatment before implant placement were included in this retrospective study. All patients received simultaneous bone augmentation surgery and implant placement with xenogeneic bone ring grafts. We evaluated the postoperative efficacy of the bone ring technique with xenogeneic bone grafts using radiographical and clinical parameters. Survival rates of implants were 100%. Cone-beam computed tomography revealed that the xenogeneic bone ring graft had significantly sufficient horizontal bone augmentation below the implant neck platform to 0 mm, 1 mm, 2 mm, and 3 mm. It could also provide an excellent peri-implant tissue condition during the 1-year follow-up after loading. The bone ring technique with xenogeneic bone ring graft could increase and maintain horizontal bone mass in the region of the implant neck platforms in serious horizontal bone defects.

Effectiveness of the bone ring technique and simultaneous implant placement for vertical ridge augmentation: a systematic review

Background

Dimensional changes after dental extraction frequently lead to situations in which bone augmentation procedures are required prior to dental implant placement. Bone ring technique (BRT) has been described as a one-stage approach to restore vertical alveolar ridge defects, in which an autogenous or allogeneic cortico-cancellous bone block graft is stabilized with a dental implant inserted simultaneously. The objective of this systematic review was to evaluate the clinical performance of BRT.

Materials and methods

This review was conducted according to PRISMA guidelines. An electronic search was conducted in four databases: (1) The National Library of Medicine (MEDLINE/PubMed) via Ovid; (2) Web of Science (WOS); (3) SCOPUS; and (4) Cochrane Central Register of Controlled Trials (CENTRAL). The Newcastle-Ottawa Quality Assessment Scale and The Joanna Briggs Institute Critical Appraisal tool were used to assess the quality of evidence in the studies reviewed.

Results

Sixteen studies with a total of 186 patients treated with 219 bone rings bocks were included in the review. The studies showed a mean bone gain of 4.94 mm, mean bone resorption of 0.83 mm, and mean marginal bone loss of 0.57 mm after a mean follow-up period of 13.35 months. A mean bone ring survival rate of 97.26% and implant survival rate of 94.97% were recorded.

Conclusions

BRT would appear to be an adequate alternative technique for restoring single vertical alveolar ridge defects with simultaneous dental implant placement. However, further studies comparing this technique with other vertical ridge augmentation procedures in different clinical scenarios are needed to confirm the present results.