Biological effects of compressive forces exerted on particulate bone grafts during socket preservation: animal study

Internal Allo-Cortical Tenting: A Modified Ridge Split Technique in Three-Dimensional Ridge Augmentation

Three-dimensional (3D) alveolar ridge deficiencies necessitate horizontal and vertical bone reconstruction for optimal implant positioning. Despite several available techniques, achieving desired augmentation outcomes remains challenging. This case study aims to present a modified ridge split technique for bone reconstruction in horizontal and vertical dimensions. The proposed technique was used to reconstruct the horizontal and vertical ridge defect from removing a previously failed implant. This technique includes placing a cortical allograft plate as an internal tent in the split ridge. A portion of the plate was inserted into the ridge, while the other part was placed in the coronal of the vertical defect. Additional guided bone regeneration was performed around the tented plate on both the buccal and lingual sides. After 5 months, cone beam computerized tomography revealed sufficient bone formation in horizontal and vertical dimensions. Within the limitations of the present case study, internal cortical tenting would be a reliable method for 3D bone reconstruction in cases where the ridge split is feasible.

In Vitro Handling Characteristics of a Particulate Bone Substitute for Ridge Preservation Procedures

While particulate bone substitute materials are applied in a variety of augmentation procedures, standardized defects are being used for preclinical testing. This in vitro study evaluated the density and homogeneity of a particulate bone substitute in ridge preservation procedures. Premolars and molars were extracted in ten semimandibles of minipig cadavers. Light body impression material was used for determining the volume of the extraction sites followed by augmentation with particulate material, thereby weighing the graft material needed. Microradiographs and histologic sections were obtained for evaluating the homogeneity and density of the augmentation material. Statistical analyses were based on Shapiro-Wilk tests, Spearman's rho and one sample Wilcoxon test followed by Bonferroni-Holm correction for multiple testing (α = 0.05). Based on 103 single alveoli evaluated, the mean volume determined was 0.120 cm3 requiring a mean amount of graft material of 0.155 g. With only three exceptions, all parameters (volume, mass of augmentation material, density and homogeneity) correlated significantly (p < 0.020). The apical parts of the alveoli showed reduced density as compared to the middle parts (p < 0.001) and the homogeneity of the augmentation material was also lower as compared to the middle (p < 0.001) and cervical parts (p Collapse

Key Words

• alveolar ridge augmentation
• bone substitute materials
• ridge preservation

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Affiliation(s)

Samira Dahl
Virgilia Klär-Quarz
Annika Schulz
Matthias Karl
Tanja Grobecker-Karl Department of Prosthodontics, Saarland University, 66421 Homburg, Saar, Germany; (S.D.); (V.K.-Q.); (A.S.); (M.K.)

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Dimensional changes after horizontal and vertical guided bone regeneration without membrane fixation using the retentive flap technique: A 1-year retrospective study

AIM

To evaluate the dimensional changes after horizontal and vertical guided bone regeneration (GBR) without membrane fixation using the retentive flap technique.

METHODS

This study retrospectively examined two cohorts that received vertical or horizontal ridge augmentations (VA or HA groups). GBR was performed using particulate bone substitutes and resorbable collagen membranes. The augmented sites were stabilized using the retentive flap technique without any additional membrane fixation. The augmented tissue dimensions were assessed using cone-beam computed tomography at preoperative, immediately postoperative (IP), 4 months (4M), and 1 year (1Y).

RESULTS

Postoperative vertical bone gain in 11 participants of VA group amounted to 5.96 ± 1.88 mm at IP, which decreased to 5.53 ± 1.62 at 4M and to 5.26 ± 1.52 mm at 1Y (intragroup p < 0.05). The horizontal bone gain at IP in 12 participants amounted to 3.98 ± 2.06 mm, which decreased to 3.02 ± 2.06 at 4M and to 2.48 ± 2.09 mm at 1Y (intragroup p < 0.05). The mean implant dehiscence defect height after 1Y was 0.19 ± 0.50 mm in the VA group, and 0.57 ± 0.93 mm in the HA group.

CONCLUSION

GBR without membrane fixation using the retentive flap technique seems to preserve the radiographic bone dimensions of vertically augmented sites. This technique may be less effective at preserving the width of the augmented tissue.

Bone Graft Packing and Its Association with Bone Regeneration in Maxillary Sinus Floor Augmentations: Histomorphometric Analysis of Human Biopsies

Research in maxillary sinus floor augmentation (MSFA) focussed on the optimisation of microstructural parameters such as microporosity and particle size of bone substitute particles (BS). However, little is known about the impact of BS packing and the corresponding (void) interparticular space on bone regeneration. The aim of this study was to characterise the spatial distribution of BS and its association with BS integration 6 ± 1 months after MSFA. Histological thin-ground sections of 70 human sinus biopsies were histomorphometrically analysed: In serial zones of 100 µm proceeding from the sinus floor (SF) up to the apical end of the biopsy, we measured the distribution of BS particles within these zones in terms of volume (BSV/TV), number and size of BS particles, interparticle spacing (BS.Sp) and bone-to-BS contact. BS particles were not homogeneously distributed over the length of biopsies: The first 200 µm directly adjacent to the SF represented a zone poor in BS particles but with high osteogenic potential. Graft packing density increased from the SF towards the apical part of the AA. Integration of BS particles was inversely associated with the distance to the SF and the graft packing density. A high packing density through excessive compaction of BS particles should be avoided to optimise the macrostructural environment for bone regeneration.

In Vitro Toxicity of Bone Graft Materials to Human Mineralizing Cells

Bone graft materials from synthetic, bovine, and human sources were analyzed and tested for in vitro cytotoxicity on dental pulp stem cells (DPSCs) and osteosarcoma cells (Saos-2). Raman spectroscopy indicated significant amounts of collagen only in human bone-derived materials, where the mineral to protein ratio was 3.55 ± 0.45, consistent with bone. X-ray fluorescence revealed tungsten (W) concentrations of 463 ± 73, 400 ± 77, and 92 ± 42 ppm in synthetic, bovine, and human bone chips, respectively. When these chips were added to DPSCs on tissue culture plastic, the doubling times after two days were the same as the controls, 16.5 ± 0.5 h. Those cultured with synthetic or bovine chips were 96.5 ± 8.1 and 25.2 ± 1.4 h, respectively. Saos-2 was more sensitive. During the first two days with allogeneic or bovine graft materials, cell numbers declined. When DPSC were cultured on collagen, allogeneic and bovine bone chips did not increase doubling times. We propose cytotoxicity was associated with tungsten, where only the concentration in human bone chips was below 184 ppm, the value reported as cytotoxic in vitro. Cells on collagen were resistant to bone chips, possibly due to tungsten adsorption by collagen.

Horizontal guided bone regeneration on knife-edge ridges: A retrospective case-control pilot study comparing two surgical techniques

INTRODUCTION

Studies evaluating guided bone regeneration (GBR) on knife-edge ridges using absorbable membranes with staged approaches have reported various horizontal bone gains. This study compared the horizontal bone gain obtained via a conventional technique of GBR and a recently-reported technique. Bone loss during the healing process was also measured.

METHODS

Consecutive patients who underwent GBR on knife-edge ridges via a conventional technique (control group) or the Sausage Technique (test group) were included in this study. GBR was performed using a collagen membrane and deproteinized bovine bone mineral combined with an autogenous graft at a 1:1 ratio. Cone-beam computed tomography (CBCT) was performed preoperatively, postoperatively, and after the patient healed. Horizontal bone width was measured on CBCT images 2 mm apical from the top of the crest. The preoperative CBCT and posthealing CBCT were superimposed to calculate the bone gain after healing, and the preoperative and postoperative CBCT scans were superimposed to calculate the bone gain after surgery. Bone loss during healing was calculated by subtracting the width of the ridge after healing from the postoperative width.

RESULTS

The mean horizontal bone gain was significantly lower in the control group (2.7 ± 1.8 mm; 83.2%) than in the test group (5.3 ± 2.3 mm; 216.8%) (p = 0.003). The average horizontal bone loss between regeneration and implant placement was 0.9 mm in the control group (27.9%) and 2.1 mm in the test group (29.4%). While the absolute bone loss was significantly different (p = 0.012), the percentage of bone resorption was not (p = 0.608).

CONCLUSION

The new technique resulted in significantly more bone gain than a conventional GBR technique. The rate of graft resorption during healing was stable regardless of the amount of grafted material.

The effect of hard-type crosslinked hyaluronic acid with particulate bone substitute on bone regeneration: positive or negative?

Purpose

Methods

Results

Conclusions

Efficacy and Safety of Concentrated Growth Factor Fibrin on the Extraction of Mandibular Third Molars: A Prospective, Randomized, Double-Blind Controlled Clinical Study

PURPOSE

To investigate the efficacy and safety of concentrated growth factor fibrin (CGF) for the extraction of mandibular third molars.

PATIENTS AND METHODS

This was a randomized, double-blind, and controlled clinical study. Patients who underwent mandibular impacted tooth extraction were randomly divided into 2 groups. In the CGF group, the tooth extraction fossa was utilized to place CGF gel. In the control group, the fossa was filled with serum. The visual analogue scale (VAS), reductions in swelling and trismus, incidence of postoperative dry socket, distal periodontal depth and bone regeneration of the second molar, and bone density (BMD) of the extraction fossa at 24 weeks were evaluated.

RESULTS

One hundred eighteen patients were enrolled in this study. There was no significant difference in baseline clinical characteristics between the 2 groups. The pain score of the CGF group was significantly lower than that of the control group at 2, 24, and 48 hours after operation. There was no significant difference in the reduction in swelling or trismus between the 2 groups. There were no cases of dry socket in the CGF group and 3 cases of dry socket in the control group. The periodontal probing depth and bone regeneration of the second molar when the socket was implanted with CGF were better than those that healed naturally (P < .05). The bone mineral density of each group was significantly increased at 24 weeks but was significantly different between groups (P < .05).

CONCLUSION

CGF can effectively reduce reactive tooth extraction pain and help avoid dry sockets. It can promote periodontal tissue and bone healing in distal and extracted sockets.

Concepts for prevention of complications in implant therapy

The use of dental implants is nowadays a well-accepted and highly predictable treatment modality for restoring the dentition and reestablishing the masticatory function of edentulous and partially edentulous patients. Despite the high predictability and excellent long-term survival rates reported for implant therapy, complications may still occur and can jeopardize both short- and long-term success. The present paper provides an overview on the most important aspects related to the etiology, prevention, and management of complications associated with implant therapy. Data from the literature indicate that a number of factors, such as surgical trauma, implant diameter, type of implant-abutment connection, abutment disconnection and reconnection, presence of microgap, and implant malpositioning, can substantially influence the biologic processes of bone remodeling and biofilm formation, thus increasing the rate of short- and long-term hard- and soft-tissue complications. Other factors, such as excess cement at cement-retained prosthetic restorations, abutment mobility, and infections (e.g. peri-implant mucositis and peri-implantitis) caused by bacterial biofilm, are further causes for complications and failures. More recent evidence also indicates that besides the need for sufficient bone volume surrounding the implant, the presence of an adequate width and thickness of attached mucosa may improve biofilm control and limit crestal bone resorption. Furthermore, emerging evidence points also to the pivotal role of human factors as one of the most important causes of complications in implant dentistry. It can be concluded that clinicians need to consider all biologic and biomechanical factors affecting implant placement and survival, as well as undergo adequate training to improve their surgical skills to control and prevent implant complications. Careful patient selection and control of environmental and systemic factors, such as smoking, diabetes etc., coupled with an accurate surgical and prosthetic planning, enable a better prevention and control of infections.

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

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

Infected tooth extraction, bone grafting, immediate implant placement and immediate temporary crown insertion in a patient with severe type-B hemophilia

Haemorrhagic disorders combined with soft tissue inflammation and infection may lead to severe bleeding complications before, during or after dental treatment. In selected cases, a combined therapeutic approach involving clinical therapies and systemic and local medication could improve the treatment outcomes and the patient's quality of life. This clinical case report, presents for the first time a successful combined approach, completed in a 38-year-old male patient with severe type-B haemophilia in which an infected tooth was extracted, an immediate implant was inserted, bone grafting was performed and early implant loading was successfully applied. In addition to the clinical therapy, medication was provided orally, systemically and locally, thus preventing the haemorrhagic complications and improving the patient's quality of life.

Deproteinized bovine bone derived with collagen improves soft and bone tissue outcomes in flapless immediate implant approach and immediate provisionalization: a randomized clinical trial

OBJECTIVES

This study aimed at evaluating soft and hard tissue dimensions after immediate implant placement and immediate temporization with or without alveolar preservation at the maxillary anterior region.

MATERIALS AND METHODS

Twenty-two patients needing maxillary incisor extraction and with the possibility of immediate implant placement were randomly assigned to the following groups: test (n = 11): immediate implant placement + deproteinized bovine bone derived with collagen inserted into the alveolus or control (n = 11): immediate implant placement without biomaterial. All soft tissue measurements were evaluated at baseline, 3 months, and 6 months after implant therapy. Cone beam tomography was performed at baseline and at 6 months after implant placement to evaluate hard tissue dimension.

RESULTS

The test group presented higher height of soft tissue at mesiobuccal and distobuccal sites at 3 months and 6 months when compared to the control group (p < 0.05). Regarding the bone tissue, the test group showed higher buccolingual ridge dimension at 6 months when compared to the control group (p < 0.05).

CONCLUSIONS

It can be concluded that the use of deproteinized bovine bone derived with collagen together with immediate dental implants results in better soft and bone tissue outcomes than immediate implants alone.

CLINICAL RELEVANCE

The use of deproteinized bovine bone derived with collagen may enhance the results regarding soft and bone tissue in combination with immediate implant and temporization.

Bone regeneration using three-dimensional hexahedron channel structured BCP block in rabbit calvarial defects

The purpose of this study is to evaluate the efficacy of bone regeneration and volume maintenance of the three-dimensional (3D) structured biphasic calcium phosphate (BCP) block with porous hexahedron channels in a rabbit calvarial model. In this work, four circular defects (diameter: 8 mm) in calvarium of rabbits were randomly assigned to (1) negative control (control), (2) 3D hexahedron channel structured BCP block, (3) deproteinized bovine bone mineral particle, and (4) deproteinized porcine bone mineral particle. Animals were euthanized at 2 (n = 5) and 8 weeks (n = 5). Outcome measures included micro-computed tomography (CT) and histomorphometrical analysis. Results indicated that in micro-CT, BCP group showed the highest new bone volume with significant difference compared to control (p = 0.008) at 8 weeks. Histomorphometrically, total augmented area of BCP group was the highest with significant difference compared to control (p = 0.008) at 8 weeks. BCP group also maintained total volume of the original defect without collapsing. BCP block with 3D hexahedron channel structure seems to have favorable osteogenic and volume maintaining ability and highly porous structure might attribute to new bone formation. Further studies regarding the optimal internal structure and porosity of the BCP block bone substitute are needed. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2254-2262, 2019.

Efficacy of Collagen-Based Membranes in Alveolar Bone Augmentation

Collagen-based membranes (CBMs) have similar permissive bone formation capabilities when compared to non-absorbable membranes. CBMs have been classified as non-cross-linked membranes (NCLMs) and cross-linked membranes (CLMs) depending on whether the cross-linking between the collagen fibers was artificially increased. The purpose of this study is to evaluate the bone maintenance capacity between NCLMs and CLMs by comparing resorption of regenerated bone. The inclusion criteria consisted of: (1) The use of a CBM, either being an NCLM or CLM for coverage of grafted bone; (2) follow-up for more than one year; (3) the presence of the patient's orthopantomographic X-ray (OPTG) immediately following the installation of implants and one year after. The bone resorption observed in the OPTG was determined by measuring the number of exposed threads of the implant. The number of thread exposures in the implant was compared according to CBM types. OPTGs taken immediately following the installation of implants and at one year after installation were compared. The subject of the measurement was always the implant in which the greatest number of exposed threads were present in each patient. A total of 56 subjects and 97 implants were used in this study. There was no significant difference between NCLM and CLM groups (p > 0.05). However, there was a statistically significant difference (p = 0.02) between the groups when a bone graft was applied to both the maxilla and the mandible. The average number of thread exposures was less than 1.5. In this study, no comparison was made between commonly known causes of bone loss and membrane types.

A comparison of different compressive forces on graft materials during alveolar ridge preservation

Purpose

Following tooth extraction, alveolar ridge preservation (ARP) can maintain the dimensions of ridge height and width. Although previous studies have demonstrated the effects of ARP, few if any studies have investigated the compressive force applied during grafting. The aim of this study was to determine the effects of different compressive forces on the graft materials during ARP.

Methods

After tooth extraction, sockets were filled with deproteinized bovine bone mineral with 10% porcine collagen and covered by a resorbable collagen membrane in a double-layered fashion. The graft materials were compressed using a force of 5 N in the test group (n=12) and a force of 30 N in the control group (n=12). A hidden X suture was performed to secure the graft without primary closure. Cone-beam computed tomography (CBCT) was performed immediately after grafting and 4 months later, just before implant surgery. Tissue samples were retrieved using a trephine bur from the grafted sites during implant surgery for histologic and histomorphometric evaluations. Periotest values (PTVs) were measured to assess the initial stability of the dental implants.

Results

Four patients dropped out from the control group and 20 patients finished the study. Both groups healed without any complications. The CBCT measurements showed that the ridge volume was comparably preserved vertically and horizontally in both groups (P>0.05). Histomorphometric analysis demonstrated that the ratio of new bone formation was significantly greater in the test group (P<0.05). The PTVs showed no significant differences between the 2 groups (P>0.05).

Conclusions

The application of a greater compressive force on biomaterials during ARP significantly enhanced new bone formation while preserving the horizontal and vertical dimensions of the alveolar ridge. Further studies are required to identity the optimal compressive force for ARP.