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.

Treatment of an Infrabony Defect of a Maxillary Canine Tooth Using Enamel Matrix Derivatives with Allogeneic Bone Augmentation in a Dog

A 5-year-old Miniature Dachshund was presented having an infrabony pocket on the palatal aspect of the right maxillary canine tooth. The bony defect had worsened despite previous closed root planing and administration of a perioceutic agent. A second surgery using an allogeneic cancellous bone augmentation with an enamel matrix derivative was performed in the infrabony defect following open root planing. Eight months after the periodontal surgery, the osseous defect showed healing by improved periodontal probing measurements and increased radiopacity using dental radiography and computed tomography.

Gene expression, micro-CT and histomorphometrical analysis of sinus floor augmentation with biphasic calcium phosphate and deproteinized bovine bone mineral: A randomized controlled clinical trial

AIMS

The aim of this randomized controlled clinical trial was to compare the gene expression, micro-CT, histomorphometrical analysis between biphasic calcium phosphate (BCP) of 70/30 ratio and deproteinized bovine bone mineral (DBBM) in sinus augmentation.

MATERIALS AND METHODS

Twenty-four patients in need for sinus floor augmentation through lateral approach were randomized into BCP 70/30 ratio or DBBM. After at least 6 months of healing, a total of 24 bone specimens were collected from the entire height of the augmented bone at the area of implant placement and underwent micro-CT, histomorphometric and gene expression analysis. The 12 bone specimens of BCP 70/30 ratio were equally allocated to micro-CT and histologic analysis (test group, n = 6) and gene expression analysis (test group, n = 6). Similarly, the 12 bone specimens of DBBM were also allocated to micro-CT and histologic analysis (control group, n = 6) and gene expression analysis (control group, n = 6). The newly formed bone, remaining graft materials and relative change in gene expression of four target genes were assessed.

RESULTS

The micro-CT results showed no statistically significant difference in the ratio of bone volume to total volume (BV/TV ratio) for the two groups (BCP 41.51% vs. DBBM 40.97%) and the same was true for residual graft material to total volume (GV/TV ratio, BCP 9.97% vs. DBBM 14.41%). Similarly, no significant difference was shown in the histological analysis in terms of bone formation, (BCP 31.43% vs. DBBM was 30.09%) and residual graft area (DBBM 40.76% vs. BCP 45.06%). With regards to gene expression, the level of ALP was lower in both groups of bone grafted specimens compared with the native bone. On the contrary, the level of OSX, IL-1B and TRAP was higher in augmented bone of both groups compared with the native bone. However, the relative difference in all gene expressions between BCP and DBBM group was not significant.

CONCLUSIONS

The BCP, HA/β-TCP ratio of 70/30 presented similar histological and micro-CT outcomes in terms of new bone formation and residual graft particles with DBBM. The gene expression analysis revealed different gene expression patterns between augmented and native bone, but showed no significant difference between the two biomaterials.

Lateral bone augmentation with a composite graft covered with a stretched and pinned collagen membrane: A retrospective case series using cone-beam computed tomography

AIMS

(1) To assess the effectiveness of the Sausage Technique™ when applied for lateral bone augmentation by multiple experienced clinicians; (2) To identify risk indicators for a poor outcome and to assess the need for adjunctive surgery.

MATERIALS AND METHODS

All patients who had been treated with the Sausage Technique™ for lateral bone augmentation by three experienced surgeons between January 2019 and December 2021 were included in a retrospective case series. The Sausage Technique™ technique includes the use of autogenous bone chips and deproteinized bovine bone mineral (1:1 ratio), covered with a stretched and pinned collagen membrane. The increase in alveolar width between the pre-operative situation and 9 months was assessed at different levels on superimposed cone-beam CT scans.

RESULTS

Twenty-five augmentations performed in 25 patients (17 males, 8 females, mean age 51 years) were available for evaluation. Mean alveolar width increased from 4.35 to 7.43 mm at 3 mm below the crest. The mean increase of 3.08 mm (95% CI 2.10-4.06; p < 0.001) was significant. The outcome of non-containing single implant sites was significantly worse than the outcome of other sites (MD 2.67 mm; p = 0.008). The need for regrafting was 4% and the need for soft tissue augmentation was 48%. Twenty percent of the patients needed soft tissue augmentation due to a lack of keratinized mucosa width, and 32% due to a lack of buccal convexity. The former was mainly needed at multiple implant sites, whereas the latter was mainly required at single implant sites. All implant survived and remained healthy until the final follow-up.

CONCLUSION

The Sausage Technique™ is an effective bone augmentation technique. Non-containing single implant sites were associated with a poor outcome and adjunctive soft tissue augmentation was needed in about half of the patients.

Are Artificial Intelligence-Assisted Three-Dimensional Histological Reconstructions Reliable for the Assessment of Trabecular Microarchitecture?

Objectives: This study aimed to create a three-dimensional histological reconstruction through the AI-assisted classification of tissues and the alignment of serial sections. The secondary aim was to evaluate if the novel technique for histological reconstruction accurately replicated the trabecular microarchitecture of bone. This was performed by conducting micromorphometric measurements on the reconstruction and comparing the results obtained with those of microCT reconstructions. Methods: A bone biopsy sample was harvested upon re-entry following sinus floor augmentation. Following microCT scanning and histological processing, a modified version of the U-Net architecture was trained to categorize tissues on the sections. Detector-free local feature matching with transformers was used to create the histological reconstruction. The micromorphometric parameters were calculated using Bruker's CTAn software (version 1.18.8.0, Bruker, Kontich, Belgium) for both histological and microCT datasets. Results: Correlation coefficients calculated between the micromorphometric parameters measured on the microCT and histological reconstruction suggest a strong linear relationship between the two with p-values of 0.777, 0.717, 0.705, 0.666, and 0.687 for BV/TV, BS/TV, Tb.Pf Tb.Th, and Tb.Sp, respectively. Bland-Altman and mountain plots suggest good agreement between BV/TV measurements on the two reconstruction methods. Conclusions: This novel method for three-dimensional histological reconstruction provides researchers with a tool that enables the assessment of accurate trabecular microarchitecture and histological information simultaneously.

Improved ridge width with tenting screw bone augmentation using particulate and block grafts: A case report

The objective of this case report is to present the use of tenting screw bone augmentation technique for the rehabilitation of narrow horizontally deficient mandibular ridges and to evaluate the feasibility and outcomes of this approach in achieving sufficient bone volume for successful implant placement and Osseointegration. A 34-year-old woman with no significant medical history presented with bilaterally missing teeth in the lower arch. A comprehensive treatment plan was developed through assessment and Cone Beam Computed Tomography (CBCT) imaging to evaluate the ridge dimensions and plan the treatment accordingly accurately. The tenting screw technique, utilizing autogenous/autologous+allograft materials, was chosen for horizontal ridge augmentation. Bone augmentations were performed simultaneously bilaterally using tenting screws. After a 20-week healing period, CBCT scans revealed favorable bone regeneration with adequate width for successful implant placements. This case report demonstrates the potential of tenting screw bone augmentation in effectively rehabilitating mandibular ridges and achieving optimal dental implant outcomes. Further research is needed to validate these findings and assess the long-term stability and success of this technique.

The transalveolar approach with the small segmentation method for inclined maxillary sinus floor elevation: A retrospective study

OBJECTIVE

To evaluate the clinical outcome of the transalveolar approach with the small segmentation method for inclined maxillary sinus floor elevation.

METHODS

Sixty-one patients with an inclined maxillary sinus floor (tilt angle ≥ 10°) and insufficient residual bone height in the posterior maxilla were included and grouped according to the tilt angle of the sinus floor, with group A having patients with the tilt angle ≥ 10° and ≤ 30° and group B having patients with the tilt angle > 30°. After completing sinus membrane elevation and bone augmentation using bone substitute materials, the implants were inserted at the same appointment, and the restoration was completed after 5-6 months of osseointegration. The preoperative sinus floor level and sinus floor elevation achieved postoperatively were assessed and recorded. At pre- and post-operative timepoints, the sagittal plane of the cone beam computed tomography was used to evaluate the bone height changes at the peak, middle and valley points in the slope segment intended for implant implantation.

RESULTS

Osseointegration was evident in all 61 patients, and the final restoration was completed with functional loading. After assessing the normality and homogeneity of variance, two-sample t-test or nonparametric tests were employed to estimate the differences in the bone height changes. The degrees of freedom (df) for this analysis were 59. The elevation attained at the middle point in groups A and B were 6.71 ± 1.38 and 5.75 ± 1.56 mm, respectively, demonstrating a significant difference (p < 0.05). Furthermore, at the peak and valley points, group A exhibited bone height changes of 5.79 ± 1.74 and 6.06 ± 1.45 mm, respectively, compared to group B with changes measuring 4.63 ± 2.18 and 5.58 ± 2.39 mm, respectively, with no significant difference in the two groups (p ≥ 0.05). The prevalence of intraoperative sinus membrane perforation was assessed using the chi-square test. It was found that four cases in group A and five cases in group B experienced sinus membrane perforation, with no significant difference in the two groups (p ≥ 0.05, df  = 1).

CONCLUSION

The transalveolar approach using the small segmentation method suggests a promising approach for elevating the inclined maxillary sinus floor.

Evaluation of the Success of Autogenous Block Grafting in Atrophic Maxillary and Mandibular Ridges Prior to and After Implant Placement

BACKGROUND

Dental implantology's success relies on adequate bone volume and quality, necessitating bone augmentation for implant placement. Primary lateral bone augmentation, utilizing autogenous block grafts, addresses horizontal bone loss.

OBJECTIVE

This study aims to evaluate the efficacy of autogenous block grafting, specifically ramus and fibula blocks, in addressing severe atrophic ridges before and after implant placement.

METHODS

Twenty-one patients underwent block grafting, predominantly using the ramus technique (80/20 ratio). CBCT measurements assessed horizontal grafting outcomes. Implant success and bone volume changes were analyzed.

RESULTS

Post-grafting, bone width increased from 1.8-3.1 mm to 4.5-6 mm, exceeding critical thresholds. Implant success reached 95%, indicating the grafting techniques' effectiveness.

CONCLUSION

Autogenous block grafting, especially with ramus and fibula blocks, transforms severe atrophic ridges, enabling successful implant integration. Long-term follow-up is essential for a comprehensive evaluation.

CLINICAL RELEVANCE

This study provides crucial insights into autogenous block grafting's transformative impact on challenging cases, guiding future applications in reconstructive dentistry.

The Poncho Lamina Technique: A Protocol for Hard and Soft Tissue Augmentation in Atrophic Ridges Receiving Adjacent Implants

The current scientific knowledge and guidelines in bone and soft tissue augmentation suggest the use of staged surgical workflows as the gold standard of regenerative procedures during implant therapy. In this context, the process is always the same, regardless of the techniques applied: an alternate series of surgical acts that follow one another after the completion of a specific period of osseointegration or graft maturation. As a result, the overall surgical treatment is often long and invasive and induces scar tissue formation. This article proposes a novel, fast, and less-invasive biphasic protocol with the use of a well-documented cortical barrier mounted on healing screws that are further replaced by customized abutments at an early second stage. Two cases are reported, one for an upper maxillary edentulous area and the other for a mandibular, with a total of four implants placed. The results at 4 months postop showed an optimal soft tissue configuration for both cases, with adequate cervical profile generation and a sufficient supracrestal complex height above the implant platforms. Significant bone gains were also recorded through CBCT data collection, either with alveolar width measurements on axial slices, the superposition of pre-op and post-op datasets, or 3D visualization after bone volume segmentation.

Bone Allograft Acid Lysates Change the Genetic Signature of Gingival Fibroblasts

Bone allografts are widely used as osteoconductive support to guide bone regrowth. Bone allografts are more than a scaffold for the immigrating cells as they maintain some bioactivity of the original bone matrix. Yet, it remains unclear how immigrating cells respond to bone allografts. To this end, we have evaluated the response of mesenchymal cells exposed to acid lysates of bone allografts (ALBA). RNAseq revealed that ALBA has a strong impact on the genetic signature of gingival fibroblasts, indicated by the increased expression of IL11, AREG, C11orf96, STC1, and GK-as confirmed by RT-PCR, and for IL11 and STC1 by immunoassays. Considering that transforming growth factor-β (TGF-β) is stored in the bone matrix and may have caused the expression changes, we performed a proteomics analysis, TGF-β immunoassay, and smad2/3 nuclear translocation. ALBA neither showed detectable TGF-β nor was the lysate able to induce smad2/3 translocation. Nevertheless, the TGF-β receptor type I kinase inhibitor SB431542 significantly decreased the expression of IL11, AREG, and C11orf96, suggesting that other agonists than TGF-β are responsible for the robust cell response. The findings suggest that IL11, AREG, and C11orf96 expression in mesenchymal cells can serve as a bioassay reflecting the bioactivity of the bone allografts.

Socket Preservation and Guided Bone Regeneration: Prerequisites for Successful Implant Dentistry

Implant success is measured not only by implant survival but also by the long-term aesthetic and functional results. Implant placement should be prosthetically driven, with proper three-dimensional positioning for optimal support and stability of the tissues. Several procedures could be performed to ensure this requirement. While socket preservation (SP) is performed at the stage of tooth extraction, guided bone regeneration (GBR) takes place before or simultaneous to implant placement. The current review aims to summarize and discuss the procedures used for the preparation of the implant site, the preservation of the existing tissues, and their augmentation in cases of deficiency. An electronic search using Google Scholar, PubMed, and Scopus was conducted up to October 2023, in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The review summarizes the current knowledge on SP and GBR as prerequisites for future implant placement. Their indications, advantages, and limitations have been thoroughly evaluated and some recommendations for further research have been suggested. Implant placement in sites with severe bone resorption is extremely challenging. It necessitates the application of different surgical techniques, especially augmentation procedures, including guided bone regeneration. The need for such procedures could be avoided or at least minimized by the execution of SP after tooth extraction or immediate/early implant placement.

Maxillary Sinus Lift Procedures: An Overview of Current Techniques, Presurgical Evaluation, and Complications

A maxillary sinus lift procedure is indicated if a dental implant needs to be placed in the posterior maxilla with limited bone available to accommodate a dental implant. Both open and closed sinus lifting procedures are reliable approaches for increasing the bone volume needed to support proper implant positioning. However, these methods can lead to several complications. In addition to the general complications commonly linked to oral surgery, such as swelling or hematoma, the primary complication in open sinus lifting is typically the perforation of the Schneiderian membrane during osteotomy. Detailed and extensive presurgical evaluation is crucial to minimize such complications. The objective of this study was to delineate contemporary trends in sinus lift surgery, with a specific emphasis on different techniques of sinus lift procedure, anatomical and surgical factors, presurgical evaluation, bone grafting, and the practical implications of these factors in implant dentistry cases involving a deficient posterior maxilla. In conclusion, while both osteotome and lateral window techniques can assist clinicians in addressing the complexities of implant placement in a deficient posterior maxilla, bone height before implantation remains a critical factor in determining the success and longevity of implants.

Clinical Study of 14 Cases of Bone Augmentation with Selective Laser Melting Titanium Mesh Plates

Additive manufacturing techniques are being used in the medical field. Orthopedic hip prostheses and denture bases are designed and fabricated based on the patient's computer-aided design (CAD) data. We attempted to incorporate this technique into dental implant bone augmentation. Surgical simulation was performed using patient data. Fourteen patients underwent bone augmentation using a selective laser melting (SLM) titanium mesh plate. The results showed no evidence of infection in any of the 14 patients. In 12 patients, only one fixation screw was used, and good results were obtained. The SLM titanium mesh plate was good adaptation in all cases, with bone occupancy greater than 90%. The average bone resorption of the marginal alveolar bone from the time of dental implant placement to the time of the superstructure placement was 0.69 ± 0.25 mm. Implant superstructures were placed in all cases, and bone augmentation with SLM titanium mesh plates was considered a useful technique.

Guided bone regeneration in implant dentistry: Basic principle, progress over 35 years, and recent research activities

Bone augmentation procedures are frequent today in implant patients, since an implant should be circumferentially anchored in bone at completion of bone healing to have a good long-term stability. The best documented surgical technique to achieve this goal is guided bone regeneration (GBR) utilizing barrier membranes in combination with bone fillers. This clinical review paper reflects 35 years of development and progress with GBR. In the 1990s, GBR was developed by defining the indications for GBR, examining various barrier membranes, bone grafts, and bone substitutes. Complications were identified and reduced by modifications of the surgical technique. Today, the selection criteria for various surgical approaches are much better understood, in particular, in post-extraction implant placement. In the majority of patients, biodegradable collagen membranes are used, mainly for horizontal bone augmentation, whereas bioinert PTFE membranes are preferred for vertical ridge augmentation. The leading surgeons are using a composite graft with autogenous bone chips to accelerate bone formation, in combination with a low-substitution bone filer to better maintain the augmented bone volume over time. In addition, major efforts have been made since the millenium change to reduce surgical trauma and patient morbidity as much as possible. At the end, some open questions related to GBR are discussed.

Lateral augmentation of the jaw by the split expansion ridge technique. A critical review

Bone augmentation has become a routine procedure to enhance and/or repair a deficient or resorbed alveolar ridge for predictable and successful implant placement. The split expansion ridge i.e., the alveolar ridge splitting (ARS) procedure, is one of the less invasive procedures, and is characterized by minor morbidity. This would allow to widen narrow ridges in order to allow implant reconstruction in a sufficient bone volume. Its efficacy and long-term stability rely upon clinical opinions and long-term retrospective studies, while prospective comparative studies and randomized controlled trials are rare. This critical review presents the development of this technique, describes the surgical procedure, and provides technical notes and modifications. The learning curve and in-depth knowledge of the oral anatomy, as well as the recognition of incidence and management of complications are of utmost importance in the clinical application of the ARS procedure.

Palatal bone block: A predictable bone augmentation technique for restricted maxillary defect

Bone grafting for implant dentistry depends on bone quality, quantity, and biological principles for good outcome. Autogenous bone as donor remains the gold standard among all the available materials. However, it carries unpredictable morbidity and need for different surgical sites. In our report, we describe a simplified approach in bone augmentation for restricted maxillary atrophic defect within the same surgical site as a harvesting site. The method can be an alternative for different intraoral surgical harvesting sites. The patient's left maxillary central incisor before treatment had a large bony defect which was reconstructed though single site approach of augmentation. The implant-supported restoration with healthy periodontium around even after 2 years of review looks promising. The approach can be an alternative for different intraoral surgical sites.

Group 1 ITI Consensus Report: The role of bone dimensions and soft tissue augmentation procedures on the stability of clinical, radiographic, and patient-reported outcomes of implant treatment

OBJECTIVES

The aims of Working Group 1 were to address the role (i) of the buccolingual bone dimensions after implant placement in healed alveolar ridge sites on the occurrence of biologic and aesthetic complications, and (ii) of soft tissue augmentation (STA) on the stability of clinical, radiographic, and patient-related outcomes of implant treatments.

MATERIALS AND METHODS

Two systematic reviews were prepared in advance of the Consensus Conference and were discussed among the participants of Group 1. Consensus statements, clinical recommendations, recommendations for future research, and reflections on patient perspectives were based on structured group discussions until consensus was reached among the entire group of experts. The statements were then presented and accepted following further discussion and modifications as required by the plenary.

RESULTS

Dimensional changes of the alveolar ridge occurred after implant placement in healed sites, and a reduction in buccal bone wall thickness (BBW) of 0.3 to 1.8 mm was observed. In healed sites with a BBW of <1.5 mm after implant placement, increased vertical bone loss, and less favorable clinical and radiographic outcomes were demonstrated. Implants with buccal dehiscence defects undergoing simultaneous guided bone regeneration, showed less vertical bone loss, and more favorable clinical and radiographic outcomes, compared to non-augmented dehiscence defects during initial healing. At healthy single implant sites, probing depths, bleeding and plaque scores, and interproximal bone levels evaluated at 1 year, remained stable for up to 5 years, with or without STA. When single implant sites were augmented with connective tissue grafts, either for soft tissue phenotype modification or buccal soft tissue dehiscence, stable levels of the soft tissue margin, and stable or even increased soft tissue thickness and/or width of keratinized mucosa could be observed from 1 to 5 years. In contrast, non-augmented sites were more prone to show apical migration of the soft tissue margin in the long-term. Favorable aesthetic and patient-reported outcomes after STA were documented to be stable from 1 to 5 years.

CONCLUSIONS

It is concluded that dimensional changes of the alveolar ridge occur after implant placement in healed sites and that sites with a thin BBW after implant placement are prone to exhibit less favorable clinical and radiographic outcomes. In addition, it is concluded that STA can provide stable clinical, radiographic, aesthetic, and patient-reported outcomes in the medium and long-term.

Avoiding errors and complications related to immediate implant placement in the esthetic area with a mucogingival approach

Immediate implant placement is considered the treatment of choice for single tooth replacement in the esthetic area. However, this treatment is associated with several critical drawbacks related to the inadequate assessment/management of the soft and hard peri-implant tissues and their subsequent remodeling, resulting in peri-implant soft-tissue defects that can lead to impaired esthetic outcomes in time. We describe in detail how the mucogingival approach to immediate implant placement ensures a standard result regardless of the baseline soft-hard tissue situation. Fully guided implant placement guarantees an adequate three-dimensional implant placement, the flap design makes it possible to perform bone augmentation with complete visibility of the area being treated, allows soft tissue augmentation with proper fixation of the connective tissue graft, and the placement of an immediate provisional ensures stabilization of the peri-implant tissues throughout the healing period.

Complications and treatment errors in peri-implant hard tissue management

Bone augmentation procedures aim to regenerate the deficient alveolar ridge to properly place dental implants that are completely surrounded by bone. However, these are invasive and technically demanding surgeries that are not free of either complications or treatment errors. Careful patient selection and preparation is a mandatory process to reduce the rate of complications in bone regeneration procedures, irrespective of the technique used. It is important to assess the cost benefit of the intervention and to evaluate the potential impact on the patient's quality of life, especially in the elderly and medically compromised patients. Most common postoperative complications are wound dehiscences, which may be reduced, at least partially, by proper knowledge of the surgical technique and the craniofacial anatomy. Other complications that may appear are postoperative infections or nerve injuries. The aim of this narrative review is to summarize the best available scientific evidence on the incidence of complications, as well as the ideal strategies for their prevention and management. Depending on the severity of the complication, treatment approaches may vary and can include drug prescription or even surgical re-entries to remove exposed barrier membranes or contaminated bone grafts. Adequate prevention and proper management of complications associated with bone augmentation interventions are a requirement for clinicians carrying out these demanding procedures. A series of cases illustrating proper management of complications in different clinical scenarios is presented.

Individual "alveolar phenotype" limits dimensions of lateral bone augmentation

AIM

Alveolar ridge resorption following tooth extraction often renders a lateral bone augmentation inevitable. Some patients, however, suffer from severe early (during graft healing, E_res ) and/or late (during follow-up, L_res ) graft resorption. We explored the hypothesis that the "individual phenotypic dimensions" may partially explain the degree of such resorptions.

MATERIALS AND METHODS

Patients who underwent a guided bone regeneration (GBR) procedure were screened for inclusion according to the following criteria: (1) a relatively symmetrical maxillary arch; (2) an intact contra-lateral alveolar bone dimension; (3) the availability of a pre-operative cone-beam CT (CBCT); (4) a CBCT taken immediately after GBR, and (5) at least one CBCT scan ≥6 months after surgery. CBCT scans from different timepoints were registered and imported into the Mimics software (Materialise, Leuven, Belgium). Bone dimensions of the contra-lateral site of the augmentation, representing the "individual phenotypical dimension (IPD) of the alveolar crest", were superimposed on the augmented site and registered accordingly. As such, E_res and L_res could be measured over time, in relation to the IPD (in two dimensions; per millimetre apically from the alveolar crest, in the centre of the GBR), as well as in three dimensions (the entire GBR, 2 mm away from the mesial, distal, and apical border for standardization).

RESULTS

A total of 17 patients (23 augmented sites) were included. After E_res , the outline of the augmentation was in general located ±1 mm outside the IPD, but ≥1.5 years after GBR, it further moved towards the IPD (85% within 0.5 mm distance).

CONCLUSIONS

Within the limitations of this study, the results indicate that the dimensions of a lateral bone augmentation are defined by the "individual phenotypic bone boundaries" of the patient.

A tooth-supported titanium mesh bending and positioning module for alveolar bone augmentation and improving accuracy

OBJECTIVE

Guided bone regeneration with titanium mesh is a commonly used bone augmentation technique. However, deformation and sliding may occur during the installation of titanium mesh, which may lead to poor accuracy of bone augmentation. This article presented three cases, which describe a tooth-supported titanium mesh bending and positioning module aiming to improve the precision of bone augmentation.

CLINICAL CONSIDERATIONS

After designing the ideal bone increment volume digitally, print out the difference bone module between the ideal and existing bone mass and one or two wings. The wings are supported by the adjacent teeth to show the ideal bone mass in the patients' mouth. Finally, the titanium mesh is bent and installed in the ideal position by the module.

CONCLUSIONS

A favorable outcome has been preliminarily confirmed in these cases, the average vertical bone gain was 4.16 mm and the average horizontal gain was 7.48 mm after 6 months. Using the module in the treatment of patients with bone augmentation can effectively improve the accuracy, the maximum deviation was 1.5 mm and the mean was 0.6 mm.

CLINICAL SIGNIFICANCE

This study improves the bone augmentation technology with titanium mesh. The titanium mesh is fixed in the ideal position, which facilitates subsequent implantation and denture repair.

Ultraviolet Light Treatment of Titanium Microfiber Scaffolds Enhances Osteoblast Recruitment and Osteoconductivity in a Vertical Bone Augmentation Model: 3D UV Photofunctionalization

Vertical bone augmentation to create host bone prior to implant placement is one of the most challenging regenerative procedures. The objective of this study is to evaluate the capacity of a UV-photofunctionalized titanium microfiber scaffold to recruit osteoblasts, generate intra-scaffold bone, and integrate with host bone in a vertical augmentation model with unidirectional, limited blood supply. Scaffolds were fabricated by molding and sintering grade 1 commercially pure titanium microfibers (20 μm diameter) and treated with UVC light (200-280 nm wavelength) emitted from a low-pressure mercury lamp for 20 min immediately before experiments. The scaffolds had an even and dense fiber network with 87% porosity and 20-50 mm inter-fiber distance. Surface carbon reduced from 30% on untreated scaffold to 10% after UV treatment, which corresponded to hydro-repellent to superhydrophilic conversion. Vertical infiltration testing revealed that UV-treated scaffolds absorbed 4-, 14-, and 15-times more blood, water, and glycerol than untreated scaffolds, respectively. In vitro, four-times more osteoblasts attached to UV-treated scaffolds than untreated scaffolds three hours after seeding. On day 2, there were 70% more osteoblasts on UV-treated scaffolds. Fluorescent microscopy visualized confluent osteoblasts on UV-treated microfibers two days after seeding but sparse and separated cells on untreated microfibers. Alkaline phosphatase activity and osteocalcin gene expression were significantly greater in osteoblasts grown on UV-treated microfiber scaffolds. In an in vivo model of vertical augmentation on rat femoral cortical bone, the interfacial strength between innate cortical bone and UV-treated microfiber scaffold after two weeks of healing was double that observed between bone and untreated scaffold. Morphological and chemical analysis confirmed seamless integration of the innate cortical and regenerated bone within microfiber networks for UV-treated scaffolds. These results indicate synergy between titanium microfiber scaffolds and UV photofunctionalization to provide a novel and effective strategy for vertical bone augmentation.

Bone Formation on Murine Cranial Bone by Injectable Cross-Linked Hyaluronic Acid Containing Nano-Hydroxyapatite and Bone Morphogenetic Protein

New injection-type bone-forming materials are desired in dental implantology. In this study, we added nano-hydroxyapatite (nHAp) and bone morphogenetic protein (BMP) to cross-linkable thiol-modified hyaluronic acid (tHyA) and evaluated its usefulness as an osteoinductive injectable material using an animal model. The sol (ux-tHyA) was changed to a gel (x-tHyA) by mixing with a cross-linker. We prepared two sol−gel (SG) material series, that is, x-tHyA + BMP with and without nHAp (SG I) and x-tHyA + nHAp with and without BMP (SG II). SG I materials in the sol stage were injected into the cranial subcutaneous connective tissues of mice, followed by in vivo gelation, while SG II materials gelled in Teflon rings were surgically placed directly on the cranial bones of rats. The animals were sacrificed 8 weeks after implantation, followed by X-ray analysis and histological examination. The results revealed that bone formation occurred at a high rate (>70%), mainly as ectopic bone in the SG I tests in mouse cranial connective tissues, and largely as bone augmentation in rat cranial bones in the SG II experiments when x-tHyA contained both nHAp and BMP. The prepared x-tHyA + nHAp + BMP SG material can be used as an injection-type osteoinductive bone-forming material. Sub-periosteum injection was expected.

Clinical evaluation of narrow-diameter implants versus standard-diameter implants with lateral bone augmentation in posterior jaws: Three-year results of a randomized controlled trial

BACKGROUND

The aim of this study was to compare the 3-year clinical outcomes of narrow-diameter implants (NDI) with standard-diameter implants (SDI) in conjunction with lateral bone augmentation in atrophic posterior jaws.

MATERIALS AND METHODS

Fifty patients were included and randomly assigned into two groups: Patients in Group 1 received NDI (Ø3.5 mm); patients in Group 2 received SDI (Ø4.3 mm) with simultaneous lateral bone augmentation. Implant survival rates, complications, crestal bone loss, peri-implant conditions, treatment cost, and patient satisfaction were compared.

RESULTS

Three patients dropped out the follow-up. No implant loss was observed. The difference in technical complication rates between the two groups was 3.8% (95% CI: -13.7% to 21.3%). No significant differences in crestal bone loss were found between two groups at 3-year follow-up (0.55 ± 0.76 vs 0.41 ± 0.41 mm, p = .429). A total of 20.8% (5/24) of NDI were diagnosed with mucositis and 8.3% (2/24) with peri-implantitis. A total of 17.4% (4/23) of SDI showed mucositis and (1/23) 4.3% showed peri-implantitis. The total cumulative cost of treatment per patient in Group 1 (2849.6 USD, 95% CI: 2726.8-2972.4) was significantly lower than that in Group 2 (3581.4 USD, 95% CI, 3460.9-3701.9) over the 3-year follow-up (p < .01). The patient satisfaction rating of operation was significantly higher in Group 1 (85.42 ± 7.41 vs 80.48 ± 7.95, p = .033).

DISCUSSION

NDI yielded favorable implant survival, acceptable technical and biological complications, and high patient satisfaction supporting single crowns in the atrophic posterior region after 3-year follow-up. NDI might be a reasonable alternative in horizontally deficient posterior jaws.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: ChiCTR1800020426.

Reconstructive treatment of peri-implant defects-Results after three and five years

OBJECTIVES

The aim of this study was to assess the long-term efficacy of reconstructive treatment of peri-implantitis intraosseous defects.

MATERIAL AND METHODS

Peri-implant intraosseous defects were augmented using either an autogenous bone graft (AB) or a bovine-derived xenograft (BDX) in combination with a collagen membrane. Maintenance was provided every third month.

RESULTS

In the AB group, 16 patients with 25 implants remained at year five. In the BDX group, 23 patients with 38 implants remained. Between baseline and year 5, bleeding on probing (BOP) and probing pocket depth (PPD) scores were reduced in both groups (p < .001). In the AB and BDX groups, mean PPD between baseline and year five was reduced by 1.7 and 2.8 mm, respectively. The difference between groups was significant (p < .001). In the AB group, the mean bone level change at implant level between baseline and years three and five was-0,2 and -0.7 mm, respectively. In the BDX group, the mean bone level change at implant level between baseline and years three and five was 1.6 and 1.6 mm, respectively. The difference between the groups was significant (p < .001). Successful treatment (no bone loss, no probing pocket depth (PPD) > 5 mm, no suppuration, maximum one implant surface with bleeding on probing (BOP) at year five) was obtained in 9/25 implants (36%) in the AB group and in 29/37 implants (78.3%) in the BDX group.

CONCLUSIONS

Reconstructive surgical treatment of peri-implant defects using BDX resulted in more predictable outcomes than using autogenous bone over 5 years.

Gaining Soft Tissue with a Hydrogel Soft Tissue Expander: A Case Report

In this case report, we describe the treatment of a patient referred to our clinic with a hopeless tooth 21 with an attached pontic. The aim of this case report was to, first, describe the advantages and disadvantages of gaining soft tissue with a self-inflating soft tissue expander before performing a bone augmentation procedure in implant dentistry in the esthetic zone. Second, we describe how an amalgam tattoo, caused by a previously performed apicoectomy that made the extension of the raised flap to cover the augmented site esthetically undesirable, was removed. Two silicone enveloped Osmed hydrogel self-inflating soft tissue expanders were placed submucosally on the right- and left-hand side of the amalgam tattoo. One of these two perforated the overlaying mucosa after 24 days. Both tissue expanders were removed, the amalgam tattoo was excided, the site augmented, and an implant with a crown and a pontic was placed.

Comparative analysis of two biomaterials mixed with autogenous bone graft for vertical ridge augmentation: A histomorphometric study in humans

BACKGROUND

The vertical increase of the alveolar ridge dimension using allograft or xenograft mixed with autogenous bone graft and covered by a nonabsorbable high-density polytetrafluoroethylene (d-PTFE) membrane is well documented in the literature.

PURPOSE

The aim of this study was to assess vital mineralized tissue formation in vertical ridge augmentation (VRA) procedures using autogenous bone chips mixed either with an allograft or a xenograft.

METHODS

This prospective clinical trial recruited 16 partially edentulous patients to undergo vertical ridge augmentation in one or more sites, making up a total of 24 samples for histological evaluation. Patients were sequentially stratified into Group A (treated with a freeze-dried bone allograft [FDBA] mixed with autogenous bone) or to Group B (treated with a bovine xenograft mixed with autogenous bone). Histological samples were analyzed according to the biomaterial used for VRA. Histological samples were obtained on the same day of membrane removal and implant placement.

RESULTS

Thirty-three implants were placed in 16 sites of regenerated bone via VRA, 13 patients with ridge augmentation in the posterior mandible, and 3 patients with VRA in the anterior maxilla. Group A (FDBA + autogenous) and Group B (xenograft + autogenous) showed a percent vital mineralized tissue (VMT) area of 67.64 ± 16.84 and 60.93 ± 18.25, respectively. A significant difference between the two biomaterials was not observed.

CONCLUSION

When mixed with autogenous bone, either allografts or xenografts may provide a successful augmentation. Either mixture could serve as reliable alternative in VRA for obtaining a high percentage of VMT.

A new subgingival sling suture technique for periodontally accelerated osteogenic orthodontics

This study aimed to design a modified subgingival sling suture for periodontally accelerated osteogenic orthodontics (PAOO) as well as evaluate postoperative effects including gingival recession (GR), alveolar bone crest resorption, dental plague accumulation on sutures and alveolar bone augmentation. Twelve patients with bone defects in the anterior alveolar region of the mandible were included in this study. Subgingival sling suture, developed from traditional sling suture, was applied in modified PAOO operation. Probing depth, bleeding index, and GR were assessed, and cone-beam computerized tomography and laser microscope for thread surface were evaluated at baseline, postoperative 1 and 3 months to analyze the effects. Alveolar bone thickness on the labial side at the midpoint of the middle third of the root increased from 0.96 ± 0.28 mm to 3.38 ± 0.61 mm (P < .01), and that of the apical third advanced from 1.26 ± 0.33 mm to 3.61 ± 1.02 mm (P < .01), both exhibiting significant increase. No significant alveolar bone crest loss, probing depth increase, GR, and attachment loss was observed. This modified PAOO operation, associated with novel subgingival sling suture, productively augments alveolar bone volume and addresses problems in terms of GR and vertical loss of alveolar bone.

Addition of Synthetic Biomaterials to Deproteinized Bovine Bone Mineral (DBBM) for Bone Augmentation-A Preclinical In Vivo Study

(1) Aim: To investigate the effect of synthetic bone substitutes, α-tricalcium phosphate (α-TCP) or bi-layered biphasic calcium-phosphate (BBCP) combined with deproteinized bovine bone mineral (DBBM), on bone formation. (2) Methods: Thirty critical size defects were randomly treated with the following five different treatment modalities: (1) negative control (NC, empty), (2) DBBM, (3) α-TCP + DBBM (1:1), (4) BBCP 3%HA/97%α-TCP + DBBM (1:1), and (5) BBCP 6%HA/94%α-TCP + DBBM (1:1). The samples, at four weeks post-surgery, were investigated by micro-CT and histological analysis. (3) Results: A similar level of new bone formation was demonstrated in the DBBM with α-TCP bone substitute groups when compared to the negative control by histomorphometry. DBBM alone showed significantly lower new bone area than the negative control (p = 0.0252). In contrast to DBBM, the micro-CT analysis revealed resorption of the α-TCP + DBBM, BBCP 3%HA/97%α-TCP + DBBM and BBCP 6%HA/94%α-TCP + DBBM, as evidenced by a decrease of material density (p = 0.0083, p = 0.0050 and p = 0.0191, respectively), without changing their volume. (4) Conclusions: New bone formation was evident in all defects augmented with biomaterials, proving the osteoconductive properties of the tested material combinations. There was little impact of the HA coating degree on α-TCP in bone augmentation potential and material resorption for four weeks when mixed with DBBM.

A novel pilot animal model for bone augmentation using osseous shell technique for preclinical in vivo studies

OBJECTIVES

Bone grafting is commonly used to reconstruct skeletal defects in the craniofacial region. Several bone augmentation models have been developed to evaluate bone formation using novel bone substitute materials. The aim of this study was to evaluate a surgical animal model for establishing a three-dimensional (3D) grafting environment in the animal's mandibular ramus for bone augmentation using the osseous shell technique, as in humans.

MATERIALS AND METHODS

Osteological survey of New Zealand white (NZW) rabbit skull (Oryctolagus cuniculus): Initial osteological and imaging surveys were performed on a postmortem skull for a feasibility assessment of the surgical procedure. Postmortem pilot surgery and cone beam computed tomography imaging: a 3D osseous defect was created in the mandibular ramus through a submandibular incision. The osseous shell plates were stabilized with osteosynthesis fixation screws, and defects were filled with particular bone grafting material. In vivo surgical procedure: surgeries were conducted in four 8-week-old NZW rabbits utilizing two osseous shell materials: xenogeneic human cortical plates and autogenous rabbit cortical plates. The created 3D defects were filled using xenograft and allograft bone grafting materials. The healed defects were evaluated for bone formation after 12 weeks using histological and cone beam computed tomography imaging analysis.

RESULTS

Clinical analysis 12 weeks after surgery revealed the stability of the 3D grafted bone augmentation defects using the osseous shell technique. Imaging and histological analyses confirmed the effectiveness of this model in assessing bone formation.

CONCLUSIONS

The proposed animal model is a promising model with the potential to study various bone grafting materials for augmentation in the mandibular ramus using the osseous shell technique without compromising the health of the animal. The filled defects could be analyzed for osteogenesis, quantification of bone formation, and healing potential using histomorphometric analysis, in addition to 3D morphologic evaluation using radiation imaging.

Sinus augmentation procedure via the lateral window technique-Reducing invasiveness and preventing complications: A narrative review

Sinus augmentation has become an integrated surgical phase in posterior maxillary implant prosthesis reconstruction. Since the residual alveolar bony height usually requires additional volume particularly at this anatomical region, sinus floor augmentation is advocated routinely. Over the years, Implant success rate is proved to be comparable to the one in the pristine bone, which is well documented in the literature. Anatomical aspects as well as surgeon skills are at most importance to achieve predictable outcome. In this narrative review, the different osteotomy techniques, the indications toward 1 or 2-stage approaches, the control of the Schneiderian membrane integrity as well as the management of intra- and post-operative complications are thoroughly discussed according the current data. In light of the excellent long-term implant success rate concurrent with the application of contemporary advanced techniques of the sinus augmentation via the lateral wall osteotomy approach, reduce invasiveness and less complication occurrences are well documented. A well-codified patient selection involving the rhinologist as an integral medical team would be significantly beneficial toward early diagnosis. In-depth knowledge of the anatomy, execution of a well standardized surgical technique, and understanding the complication etiology and their management are prerequisites for reducing patient morbidity to minimal discomfort and predictable successful outcome.

Characterization of a cotton-wool like composite bone graft material

Bone graft materials are applied in patients to augment bone defects and enable the insertion of an implant in its ideal position. However, the currently available augmentation materials do not meet the requirements of being completely resorbed and replaced by new bone within 3 to 6 months. A novel electrospun cotton-wool like material (Bonewool^®, Zurich Biomaterials LLC, Zurich, Switzerland) consisting of biodegradable poly(lactic-co-glycolic) acid (PLGA) fibers with incorporated amorphous ß-tricalcium phosphate (ß-TCP) nanoparticles has been compared to a frequently used bovine derived hydroxyapatite (Bio-Oss^®, Geistlich Pharma, Wolhusen, Switzerland) in vitro. The material composition was determined and the degradation behavior (calcium release and pH in different solutions) as well as bioactivity has been measured. Degradation behavior of PLGA/ß-TCP was generally more progressive than for Bio-Oss^®, indicating that this material is potentially completely resorbable. Graphical abstract.

Bone preservation or augmentation simultaneous with or prior to dental implant placement: A systematic review of outcomes and outcome measures used in clinical trials in the last 10 years

AIM

To evaluate outcome measures and methods of assessment in clinical studies on bone augmentation/preservation procedures for the placement of dental implants.

MATERIALS AND METHODS

A systematic search was performed on three databases from January 2011 to April 2021 to identify clinical studies reporting on any type of bone augmentation/preservation procedure. The outcomes that have been used to assess efficacy or performance in each study were registered and assigned to different domains (group of outcomes). The review followed the Preferred Reporting Items for Systematic Review and Meta-Analyses statement.

RESULTS

Seven-hundred and eighty-three publications were included. Only 81.8% of the papers had a clear definition of their primary outcome. The rate of complications (59.3%), implant survival (58.2%), 3D radiographic bone gain/change (30%), marginal bone level (MBL; 29%), and histological outcomes (25.5%) were the most frequently reported outcome domains. The most commonly used primary outcome was 3D radiographic bone gain/change (25.8%), followed by implant survival (13.0%). Patient-reported outcome measures (PROMs) were reported in 15.7% of studies. Differences in the reported outcomes were observed among different types of bone preservation/augmentation interventions (i.e., alveolar ridge preservation, immediate implants, horizontal and/or vertical ridge augmentation, and sinus floor augmentation).

CONCLUSION

Within the past decade, great heterogeneity was observed among the outcomes considered in studies evaluating bone preservation/augmentation procedures. Three-dimensional radiographic bone gain/change was the most routinely reported main outcome variable, while PROMs were rarely reported.

Bone preservation or augmentation simultaneous with or prior to dental implant placement: A systematic review of outcomes and outcome measures used in clinical trials in the last 10 years

AIM

To evaluate outcome measures and methods of assessment in clinical studies on bone augmentation/preservation procedures for the placement of dental implants.

MATERIALS AND METHODS

A systematic search was performed on three databases from January 2011 to April 2021 to identify clinical studies reporting on any type of bone augmentation/preservation procedure. The outcomes that have been used to assess efficacy or performance in each study were registered and assigned to different domains (group of outcomes). The review followed the Preferred Reporting Items for Systematic Review and Meta-Analyses statement.

RESULTS

Seven-hundred and eighty-three publications were included. Only 81.8% of the papers had a clear definition of their primary outcome. The rate of complications (59.3%), implant survival (58.2%), 3D radiographic bone gain/change (30%), marginal bone level (MBL; 29%), and histological outcomes (25.5%) were the most frequently reported outcome domains. The most commonly used primary outcome was 3D radiographic bone gain/change (25.8%), followed by implant survival (13.0%). Patient-reported outcome measures (PROMs) were reported in 15.7% of studies. Differences in the reported outcomes were observed among different types of bone preservation/augmentation interventions (i.e., alveolar ridge preservation, immediate implants, horizontal and/or vertical ridge augmentation, and sinus floor augmentation).

CONCLUSION

Within the past decade, great heterogeneity was observed among the outcomes considered in studies evaluating bone preservation/augmentation procedures. Three-dimensional radiographic bone gain/change was the most routinely reported main outcome variable, while PROMs were rarely reported.

Tooth as graft material: Histologic study

Background

An effective regenerative protocol is key to reestablish and maintain the hard and soft tissue dimensions over time. The choice of the graft material and its properties also could have an impact on the results. To prevent alveolar ridge dimensional changes, since numerous graft materials have been suggested and in the past years, a growing interest in teeth material has been observed as a valuable alternative to synthetic biomaterials.

Aim

The aim of the study was to explore the histomorphometric outcomes of tooth derivative materials as used as bone substitute material in socket preservation procedure.

Methods

After alveolar socket preservation (ASP) procedures using autologous demineralized tooth as graft material prepared by means of an innovative device, was evaluated. A total of 101 histological samples, from 96 subjects, were analyzed by evaluating the total amount of bone (BV), residual tooth material (residual graft, TT), and vital bone (VB). The section from each sample was then split in nine subsections, resulting in 909 subsections, to allow statistical comparison between the different areas.

Results

It was not noticed a statistically significant difference between maxillary and mandibular sites, being the amount of VB in upper jaw sites 37.9 ± 21.9% and 38.0 ± 22.0% in lower jaw sites and the amount of TT was 7.7 ± 12.2% in maxilla and 7.0 ± 11.1% in mandibles. None of the other considered parameters, including defect type and section position, were statistically correlated to the results of the histomorphometric analysis.

Conclusions

ASP procedure using demineralized autologous tooth‐derived biomaterial may be a predictable procedure to produce new vital bone potentially capable to support dental implant rehabilitation.

Surgical guides for guided bone augmentation: an in vitro study

AIM

To validate in vitro the accuracy of a novel method for bone augmentation of horizontal alveolar bone defects with the help of a surgical guide.

MATERIAL AND METHODS

Six cone-beam computed tomography scans of patients requiring horizontal bone augmentation were segmented and 3D printed. Two surgeons performed the bone augmentation surgery twice for each case on 3D printed models, using either a conventional or guided protocol. Each surgeon virtually planned the desired graft shape beforehand. The resulting grafts were compared linearly and volumetrically to the plan; graft density and surgical time were also analyzed.

RESULTS

There was significantly less graft volume outside the planned volume with the guided protocol (36.8% ± 14.1 vs 19.6% ± 12.3, p < 0.01). The use of a guide increased graft accuracy at several measurement points, resulting in less overfill when using the guided protocol (1.7 ± 1.7 mm at the most coronal point, 0.2 mm ± 1.4 at 25%, 0.0 mm ± 0.9 at 50%, 0.1 mm ± 1.1 at 75%, 0.4 mm ± 1.4 apically). Graft thickness was increased 1 mm coronally from the planned graft (2.8 mm ± 2.3 vs 1.8 mm ± 2.2, p = 0.04). Surgical time increased significantly when using a guide (a difference of 2m26s).

CONCLUSION

The technique, tested here in vitro, allows surgeons to improve the accuracy of the resulting graft shape, to better compact material in the coronal portion of the graft, and to reduce the amount of graft material placed outside the planned volume.

Preoperative buccal bone volume predicts long-term graft retention following augmentation in the esthetic zone: a retrospective case series

Objectives

Buccal bone augmentation in the esthetic zone is routinely used to achieve optimal clinical outcomes. Nonetheless, long‐term data are sparse, and it is unknown how baseline buccal bone volume affects the retention of the augmented volume over time.

Material and methods

This is a long‐term follow‐up retrospective case series. After a preoperative computed tomography scan, implants were placed in the anterior maxilla following guided bone regeneration, autogenous block grafting, or both. At the follow‐up, patients received a computed tomography scan and a clinical examination. Buccal bone volume was the primary outcome. Buccal bone thickness, peri‐implant, and esthetic parameters were secondary outcomes.

Results

After a median follow‐up of 6.7 years (interquartile range: 4.9–9.4), 28 implants in 19 patients (median age at augmentation: 43.3 years, interquartile range: 34.4–56.7, 53% female) were followed up. Preoperative buccal bone volume at baseline (V₀) showed a moderate correlation to final buccal bone volume (V_t, r_s = .43) but a strong correlation to the absolute volumetric change (ΔV = V_t–V₀, r_s = −.80). A linear mixed model for V_t had a large intercept of 91.39 (p < .001) and a rather small slope of .11 for V₀ (p = .11). Observed differences between treatments were not statistically significant in the mixed model. V₀ above 105 mm³ predicted a negative volume change (ΔV < 0) with a specificity of 100% and a sensitivity of 96%.

Conclusions

The results suggest higher gains in sites with lower V₀ and point to a cutoff V₀ above which the augmented volume is not retained long‐term.

The Aesthetic Contour Graft - Enhancing peri-implant soft tissue contours and pontic sites with guided bone regeneration

Objective

In this article, we will discuss strategies for enhancing peri‐implant soft tissue contours and pontic sites with hard tissue augmentation.

Clinical consideration

One of the keys to the esthetic illusion of an implant‐supported restoration is to create an ideal emergence profile. A critical part of any emergence profile is based on the height and thickness of the tissue surrounding the restoration and whether there are any defects in this tissue. Even when there is adequate bone in which to place implants, if any irregular ridge anatomy that supports this tissue is not corrected, then an unesthetic appearance of the restoration can result due to the lack of soft tissue with which to develop a proper emergence profile.

Conclusion

Most peri‐implant soft tissue deficiencies represent an underlying bony defect that can be corrected or enhanced through bone augmentation.

Clinical significance

Traditional methods of enhancing soft tissue emergence profiles around implants and pontic sites mostly involve the use of soft tissue augmentation techniques. Although there are few reports of the use of bone augmentation for this purpose, soft tissue contours can be enhanced by augmenting the underlying bone contours and, in many instances, may obviate the need for subsequent soft tissue augmentation.

Fatal fat embolism syndrome during posterior spinal fusion surgery: A case report and literature review

RATIONALE

Fat embolism syndrome (FES) is a rare but potentially lethal complication. Although serious FES is associated with long bone fractures and major joint surgery, the number of patients who develop fatal FES intraoperatively is probably higher than the described number. We herein report an extremely rare autopsy-confirmed case of fatal FES during posterior spinal fusion to enhance pedicle screw (PS) fixation with allograft bone augmentation.

PATIENT CONCERNS

A 74-year-old woman came to the hospital complaining of back pain, lower extremity pain and numbness, and intermittent claudication.

DIAGNOSIS

She was diagnosed with lumbar degenerative scoliosis and lumbar spinal canal stenosis based on imaging findings.

INTERVENTIONS

During posterior spinal fusion to enhance pedicle screw fixation with allograft bone augmentation, her blood pressure and oxygen saturation dropped significantly, so the operation was stopped, and cardiopulmonary resuscitation was performed. Chest computed tomography demonstrated bilateral diffuse alveolar infiltrates.

OUTCOMES

The patient died three days later due to fat embolism. The autopsy revealed diffuse myocardial ischemia and diffuse alveolar damage. Numerous fat emboli were observed at lung, kidney and spleen and small necrotic bone fragments, possibly derived from allograft bone debris, were found in the peripheral pulmonary artery.

LESSONS

Fatal FES associated to seemingly harmless isolated osteoporotic vertebral fractures-vertebroplasty and posterior spinal fusion has been reported. The mechanism was hypothesized to be that both vertebral fractures and spine surgery have the potential to involve bone marrow, thereby increasing intraosseous pressure, and this pressure dislodges fat and bone marrow and pushes them out into the venous circulation, causing systemic inflammation.This is the first report to show histological evidence that the allografted bone embolized to the lungs. Although several reports have indicated that inserting reinforcing materials into the tapped screw holes can enhance the pedicle screw fixation, this procedure may cause severe FES due to fat and debris of material augmentation (i.e. cement, hydroxyapatite, allograft bone). It is important for physicians, especially spinal surgeons, and anesthetists, to be aware of the potential for FES to occur during spinal surgery, which can cause serious complications in a small minority of patients.

Implant restoration of hypodontia resulting from ectodermal dysplasia: a case report

Background

Ectodermal dysplasia is a congenital genetic disorder with a prevalence of 1:10,000 to 1:100,000. The clinical features of ectodermal dysplasia include sparse hair, missing teeth, and abnormal development of the skin, sweat glands, and other tissues and organs. Since 1985, dentists have used implants to correct tooth defects in patients with ectodermal dysplasia with reasonable success rates. However, there is still no widely accepted treatment for the oral defects caused by this disease.

Case summary: This report describes a 19-year-old female patient with congenital ectodermal dysplasia, congenital absence of most of her teeth, and mandibular and maxillary dysplasia. The patient and her family were concerned about the patient’s growth and development, so she came to our hospital to restore her missing teeth. During several months of treatment, the patient underwent bone augmentation surgery for the maxilla and mandible, implant placement, a root repositioning flap, and free gingival grafting, which was completed in five stages. The patient completed the permanent implant restoration, and the desired results were achieved.

Conclusion

The patient’s mouth was restored through the use of bone augmentation and soft tissue grafting techniques, enabling appropriate function and appearance.

Survival Rates of Dental Implants in Autogenous and Allogeneic Bone Blocks: A Systematic Review

Background and Objectives: Preliminary studies emphasize the similar performance of autogenous bone blocks (AUBBs) and allogeneic bone blocks (ALBBs) in pre-implant surgery; however, most of these studies include limited subjects or hold a low level of evidence. The purpose of this review is to test the hypothesis of indifferent implant survival rates (ISRs) in AUBB and ALBB and determine the impact of various material-, surgery- and patient-related confounders and predictors. Materials and Methods: The national library of medicine (MEDLINE), Excerpta Medica database (EMBASE) and Cochrane Central Register of Controlled Trials (CENTRAL) were screened for studies reporting the ISRs of implants placed in AUBB and ALBB with ≥10 participants followed for ≥12 months from January 1995 to November 2021. The review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The risk of bias was assessed via several scoring tools, dependent on the study design. Means of sub-entities were presented as violin plots. Results: An electronic data search resulted in the identification of 9233 articles, of which 100 were included in the quantitative analysis. No significant difference (p = 0.54) was found between the ISR of AUBB (96.23 ± 5.27%; range: 75% to 100%; 2195 subjects, 6861 implants) and that of ALBB (97.66 ± 2.68%; range: 90.1% to 100%; 1202 subjects, 3434 implants). The ISR in AUBB was increased in blocks from intraoral as compared to extraoral donor sites (p = 0.0003), partially edentulous as compared to totally edentulous (p = 0.0002), as well as in patients younger than 45 as compared to those older (p = 0.044), cortical as compared to cortico-cancellous blocks (p = 0.005) and in delayed implantations within three months as compared to immediate implantations (p = 0.018). The ISR of ALBB was significantly increased in processed as compared to fresh-frozen ALBB (p = 0.004), but also in horizontal as compared to vertical augmentations (p = 0.009). Conclusions: The present findings widely emphasize the feasibility of achieving similar ISRs with AUBB and ALBB applied for pre-implant bone grafting. ISRs were negatively affected in sub-entities linked to more extensive augmentation procedures such as bone donor site and dentition status. The inclusion and pooling of literature with a low level of evidence, the absence of randomized controlled clinical trials (RCTs) comparing AUBB and ALBB and the limited count of comparative studies with short follow-ups increases the risk of bias and complicates data interpretation. Consequently, further long-term comparative studies are needed.

Effect of Er:YAG laser combined with ethylenediamine tetra acetic acid on three-walled periodontal intrabony defects adjacent to implant sites

OBJECTIVES

To investigate the clinical effect of Er:YAG laser combined with ethylenediamine tetra acetic acid (EDTA) on three-walled periodontal intrabony defects adjacent to implant sites.

METHODS

A total of 30 patients with three-walled periodontal intrabony defects adjacent to implant sites were treated with the combination therapy. Patients with three-walled intrabony defects were divided into two groups according to the depth of the intrabony pocket between the implant and natural teeth. Evaluation of wound healing was performed 10 days after the operation, and bone augmentation was evaluated 6 months after the operation.

RESULTS

Primary healing in group 1 was 92.31%, primary healing in group 2 was 82.35%. No significant difference was observed between the two groups (P>0.05). Bone augmentation in group 1 and group 2 were (2.85±1.81), (4.92±2.22) mm. There was significant difference between the two groups (P<0.05). New bone growth occurred more slowly in group 1 (0.70 mm±0.32 mm) than in group 2 (1.25 mm±0.47 mm) (P>0.05). Probe depths (PD), clinical attachment levels (CAL), and sulcus bleeding indices (SBI) showed no statistically significant difference between the two groups (P>0.05). The one-year survival rate of natural tooth in group 1 and group 2 were 100%, 94.2%, and the one-year survival rate of implants in both groups was 100%.

CONCLUSIONS

The effect of bone augmentation with combination therapy was more ideal in group 2 than in group 1. Implant placement with combination therapy may be a viable technique to reconstruct three-walled intrabony defects due to the space maintenance provided by implants and bone grafts and the good root surface biocompatibility provided by the Er:YAG laser and EDTA.

Confirmation of Calcium Phosphate Cement Biodegradation after Jawbone Augmentation around Dental Implants Using Three-Dimensional Visualization and Segmentation Software

The use of autologous bone graft for oral rehabilitation of bone atrophy is considered the gold standard. However, the available grafts do not allow a fast loading of dental implants, as they require a long healing time before full functionality. Innovative bioactive materials provide an easy-to-use solution to this problem. The current study shows the feasibility of calcium phosphate cement paste (Paste-CPC) in the sinus. Long implants were placed simultaneously with the cement paste, and provisional prosthetics were also mounted in the same sessions. Final prosthetics and the full loading took place within the same week. Furthermore, the study shows for the first time the possibility to monitor not only healing progression using Cone Beam Computer tomography (CBCT) but also material retention, over two years, on a case study example. The segmented images showed a 30% reduction of the cement size and an increased mineralized tissue in the sinus. Mechanical testing was performed qualitatively using reverse torque after insertion and cement solidification to indicate clinical feasibility. Both functional and esthetic satisfaction remain unchanged after one year. This flowable paste encourages the augmentation procedure with less invasive measure through socket of removed implants. However, this limitation can be addressed in future studies.

Gene-Activated Matrix with Self-Assembly Anionic Nano-Device Containing Plasmid DNAs for Rat Cranial Bone Augmentation

We have developed nanoballs, a biocompatible self-assembly nano-vector based on electrostatic interactions that arrange anionic macromolecules to polymeric nanomaterials to create nucleic acid carriers. Nanoballs exhibit low cytotoxicity and high transfection efficiently in vivo. This study investigated whether a gene-activated matrix (GAM) composed of nanoballs containing plasmid (p) DNAs encoding bone morphogenetic protein 4 (pBMP4) could promote bone augmentation with a small amount of DNA compared to that composed of naked pDNAs. We prepared nanoballs (BMP4-nanoballs) constructed with pBMP4 and dendrigraft poly-L-lysine (DGL, a cationic polymer) coated by γ-polyglutamic acid (γ-PGA; an anionic polymer), and determined their biological functions in vitro and in vivo. Next, GAMs were manufactured by mixing nanoballs with 2% atelocollagen and β-tricalcium phosphate (β-TCP) granules and lyophilizing them for bone augmentation. The GAMs were then transplanted to rat cranial bone surfaces under the periosteum. From the initial stage, infiltrated macrophages and mesenchymal progenitor cells took up the nanoballs, and their anti-inflammatory and osteoblastic differentiations were promoted over time. Subsequently, bone augmentation was clearly recognized for up to 8 weeks in transplanted GAMs containing BMP4-nanoballs. Notably, only 1 μg of BMP4-nanoballs induced a sufficient volume of new bone, while 1000 μg of naked pDNAs were required to induce the same level of bone augmentation. These data suggest that applying this anionic vector to the appropriate matrices can facilitate GAM-based bone engineering.

Periodontal tissue engineering using an apatite/collagen scaffold obtained by a plasma- and precursor-assisted biomimetic process

BACKGROUND AND OBJECTIVES

In the treatment of severe periodontal destruction, there is a strong demand for advanced scaffolds that can regenerate periodontal tissues with adequate quality and quantity. Recently, we developed a plasma- and precursor-assisted biomimetic process by which a porous collagen scaffold (CS) could be coated with low-crystalline apatite. The apatite-coated collagen scaffold (Ap-CS) promotes cellular ingrowth within the scaffold compared to CS in rat subcutaneous tissue. In the present study, the osteogenic activity of Ap-CS was characterized by cell culture and rat skull augmentation tests. In addition, the periodontal tissue reconstruction with Ap-CS in a beagle dog was compared to that with CS.

METHODS

The plasma- and precursor-assisted biomimetic process was applied to CS to obtain Ap-CS with a low-crystalline apatite coating. The effects of apatite coating on the scaffold characteristics (i.e., surface morphology, water absorption, Ca release, protein adsorption, and enzymatic degradation resistance) were assessed. Cyto-compatibility and the osteogenic properties of Ap-CS and CS were assessed in vitro using preosteoblastic MC3T3-E1 cells. In addition, we performed in vivo studies to evaluate bone augmentation and periodontal tissue reconstruction with Ap-CS and CS in a rat skull and canine furcation lesion, respectively.

RESULTS

As previously reported, the plasma- and precursor-assisted biomimetic process generated a low-crystalline apatite layer with a nanoporous structure that uniformly covered the Ap-CS surface. Ap-CS showed significantly higher water absorption, Ca release, lysozyme adsorption, and collagenase resistance than CS. Cell culture experiments revealed that Ap-CS was superior to CS in promoting the osteoblastic differentiation of MC3T3-E1 cells while suppressing their proliferation. Additionally, Ap-CS significantly promoted (compared to CS) the augmentation of the rat skull bone and showed the potential to regenerate alveolar bone in a dog furcation defect.

CONCLUSION

Ap-CS fabricated by the plasma- and precursor-assisted biomimetic process provided superior promotion of osteogenic differentiation and bone neoformation compared to CS.

The Role of Blood Clot in Guided Bone Regeneration: Biological Considerations and Clinical Applications with Titanium Foil

In Guided Bone Regeneration (GBR) materials and techniques are essential to achieve the expected results. Thanks to their properties, blood clots induce bone healing, maturation, differentiation and organization. The preferred material to protect the clot in Guided Bone Regeneration is the titanium foil, as it can be shaped according to the bone defect. Furthermore, its exposition in the oral cavity does not impair the procedure. We report on five clinical cases in order to explain the management of blood clots in combination with titanium foil barriers in different clinical settings. Besides being the best choice to protect the clot, the titanium foil represents an excellent barrier that is useful in GBR due to its biocompatibility, handling, and mechanical strength properties. The clot alone is the best natural scaffold to obtain the ideal bone quality and avoid the persistence of not-resorbed granules of filler materials in the newly regenerated bone. Even though clot contraction still needs to be improved, as it impacts the volume of the regenerated bone, future studies in GBR should be inspired by the clot and its fundamental properties.

Influence of soft tissue augmentation procedures around dental implants on marginal bone level changes-A systematic review

OBJECTIVES

This systematic review assessed the influence of soft tissue augmentation procedures on marginal bone level changes in partial or fully edentulous patients.

MATERIAL AND METHODS

We identified three relevant PICO questions related to soft tissue augmentation procedures and conducted a systematic search of four major electronic databases for clinical studies in systemically healthy patients receiving at least one dental implant and a minimum follow-up of one year after implant placement. The primary outcome was mean difference in marginal bone levels, and secondary outcomes were clinical and patient-related outcomes such as thickness of peri-implant mucosa, bleeding indices, and Pink Esthetic Score.

RESULTS

We identified 20 publications reporting on 16 relevant comparisons. Studies varied considerably and thus only two meta-analyses could be performed. This systematic review showed that: Soft tissue augmentation either for augmentation of keratinized mucosa or soft tissue volume inconsistently had an effect on marginal bone level changes when compared to no soft tissue augmentation, but consistently improved secondary outcomes. The combination soft and hard tissue augmentation showed no statistically significant difference in terms of marginal bone level changes when compared to hard tissue augmentation alone, but resulted in less marginal soft tissue recession as shown by a meta-analysis. Soft or hard tissue augmentation performed as contour augmentations resulted in comparable marginal bone level changes.

CONCLUSIONS

Peri-implant soft and hard tissues seem to have a bidirectional relationship: "Bone stands hard, but soft tissue is the guard".

Effect of mesoporous silica and its combination with hydroxyapatite on the regeneration of rabbit's bone defects: A pilot study

BACKGROUND

Bone volume augmentation is a routine technique used in oral implantology and periodontology. Advances in the surgical techniques and the biomaterials field have allowed a greater accessibility to these treatments. Nevertheless, dehiscence and fenestrations incidence during dental implant procedures are still common in patients with bone loss.

OBJECTIVE

The main objective is to evaluate in a pilot experimental study the biological response to mesoporous silica (MS) hybrid scaffolds and its regenerative capacity in different formulations.

METHODS

Two defects per rabbit tibia were performed (one for control and other for test) and the biomaterials tested in this study have been used to fill the bone defects, prepared in two different formulations (3D hybrid scaffolds or powdered material, in 100% pure MS form, or 50% MS with 50% hydroxyapatite (HA). Euthanasia was performed 4 months after surgery for bone histopathological study and radiographic images were acquired by computerized microtomography.

RESULTS

Results showed that radiographically and histopathologically pure MS formulations lead to a lower biological response, e.g when formulated with HA, the osteogenic response in terms of osteoconduction was greater.

CONCLUSIONS

We observed tolerance and lack of toxicity of the MS and HA, without registering any type of local or systemic allergic reaction.

The use of rhBMP2 for augmentation of established horizontal/vertical defects may require additional use of rhVEGF to achieve significant bone regeneration: An in vivo experimental study

AIM

To test the hypothesis that the use of rhBMP2 in established defects requires additional growth factors such as rhVEGF to accomplish effective bone repair.

MATERIALS AND METHODS

Horizontal/vertical defects of 2 cm length and 1 cm height were created bilaterally in the alveolar crest of the maxillae of 18 minipigs together with the extraction of all premolar teeth and one molar tooth on both sides. After 3 months of healing, defects were augmented with 0.5 g particulate PDLLA/CaCO3 composite loaded with 400 µg rhBMP2/50 µg rhVEGF165 on one side and 800 µg rhBMP2 on the other in 12 test animals, whereas defects in six control animals were sham operated and left unfilled on one side and augmented with blank carriers on the other. After 4 and 13 weeks, the animals were evaluated each for area of new bone formation (mm²) and bone density (area %).

RESULTS

Augmentations with carriers loaded with 800 g µrhBMP2 failed to induce significantly more bone than in the augmentations with unloaded carrier after 4 and 13 weeks (p = .1000, p = .381). Augmentations with carriers loaded with 400 µg rhBMP2 and 50 µg erhVEGF165 resulted in significantly increased bone formation after 13 weeks (p = .024) compared to blank carriers. Soft tissue in augmentations with combined rhBMP2/rhVEGF165 loading exhibited numerous microvessels compared to soft tissue in augmentations with rhBMP2.

CONCLUSIONS

It is concluded that effective bone regeneration in augmentations of established alveolar ridge defects may require the application of rhVEGF additionally to rhBMP2.

Manufacture and preliminary evaluation of acellular tooth roots as allografts for alveolar ridge augmentation

Alveolar ridge augmentation can be used to obtain appropriate alveolar ridge for dental implantation. A variety of bone graft materials including autogenous bone, allograft, xenograft, and alloplastic material are used in alveolar ridge augmentation. Autogenous tooth-derived bone graft material has received much attention for the past few years, because the structure and physicochemical characteristics of tooth are similar to those of bones. Compared to autogenous tooth, allogenic tooth has the advantage of extensive resources. However, the problem of cell-derived immunological rejection of allogenic tooth remains unresolved. In the present study, acellular tooth root (ATR) is obtained by an innovative combination procedure. The biocompatibility of ATR is assessed using cytotoxicity test, hemolysis test, intracutaneous reactivity test, and acute systemic toxicity test. Osseointegration is evaluated in vivo by implanting ATR into the rat tibia defect as an allograft material. The results show that the ATR has fine biocompatibility, and there is an osseointegration between ATR and bone bed at 8 weeks post operation. This study demonstrates that the ATR could be used in alveolar ridge augmentation as a kind of new tooth-derived bone graft material.