Augmentation of Exposed Implant Threads with Autogenous Bone Chips: Prospective Clinical Study

Influence of implant location on titanium-zirconium alloy narrow-diameter implants: A 1-year prospective study in smoking and nonsmoking populations

STATEMENT OF PROBLEM

Titanium-zirconium (Ti-Zr) alloy (Roxolid) narrow-diameter implants (NDIs) have been widely used for implant-supported prostheses in anterior and posterior regions in the jaws. However, the relationship between implant location and clinical outcome remains unclear.

PURPOSE

The purpose of this clinical study was to evaluate and compare the clinical and radiographic outcomes of NDIs placed in different regions of the jaws in both smokers and nonsmokers.

MATERIAL AND METHODS

Eighty-four participants scheduled to receive NDIs for tooth rehabilitation were included, and the inserted NDIs were divided into 3 groups depending on their locations: implants used to restore anterior teeth, implants used to restore premolars, and implants used to restore molars. Crestal bone loss (CBL), implant survival and success rates, bleeding on probing (BOP), and pocket probing depth (PPD) were evaluated 6 and 12 months after implant loading (α=.017 for implant survival and success rates after Bonferroni correction, α=.05 for other parameters).

RESULTS

Statistical analysis of 6- and 12-month CBL of all participants presented no statistically significant difference among the 3 groups. For smokers, the molar group presented significantly more CBL than the premolar group (0.90 ±0.94 versus 0.16 ±0.27 mm, P=.027) at the 6-month examination. The implant survival rates were 95.65%, 100%, and 100% for anterior, premolar, and molar regions, respectively (P=.283). No statistically significant difference was observed regarding periodontal parameters (P>.05).

CONCLUSIONS

Implant location has no influence on the clinical and radiographic parameters of Ti-Zr NDIs placed in a nonsmoking population. However, the combination of posterior location and smoking may induce higher risk of crestal bone loss. Caution should be taken when restoring molars for smokers with NDIs.

Guided bone regeneration

Guided bone regeneration (GBR) is a surgical procedure that utilizes bone grafts with barrier membranes to reconstruct small defects around dental implants. This procedure is commonly deployed on dehiscence or fenestration defects ≥2 mm, and mixing with autogenous bone is recommended on larger defects. Tension-free primary closure is a critical factor to prevent wound dehiscence, which is critical cause of GBR failure. A barrier membrane should be rigidly fixed without mobility. If the barrier is exposed, closed monitoring should be utilized to prevent secondary infection.

The Role of Antibiotic Prophylaxis in Reducing Bacterial Contamination of Autologous Bone Graft Collected from Implant Site

The aim of this study was to evaluate if antibiotic prophylaxis reduces the bacterial contamination of bone particles collected directly from the burs used for implant site preparation. Thirty-four patients underwent the surgical procedures for a total of 34 implant sites. One 1 gr. tablet of amoxicillin + clavulanic acid was given to the test group 12 hours and 1 hour before the surgery. The control group did not take antibiotic prophylaxis. Bone particles were collected and centrifuged. The suspensions were subjected to serial dilutions and each dilution was examined twice using a spatulation technique in Trypticase Soy Agar (TSA), in Sabouraud Dextrose Agar, and in Mitis Salivarius Agar (MSA). The number of colonies was calculated and the identification of various microorganisms was made. The most represented species, in both groups of patients, belonged to the “oral Streptococci.” For TSA, the test and control groups differed significantly (p = 0.018). Conversely, there was no significant difference for MSA (p = 0.201) and for the number of bacterial species isolated in the samples of the two groups of patients (p = 0.898). The antibiotic prophylaxis reduced, but did not cancel, the risk of infection of the autogenous particulate bone graft. This trial is registered with IRCT2017102537002N1.

Comparison of the Bone Harvesting Capacity of an Intraoral Bone Harvesting Device and Three Different Implant Drills

The aim of the present study was to compare bone-collecting capacity of bone harvesting device and minimally irrigated low-speed drilling using three implant systems. One bone harvesting device and three commercially available drill systems were compared using the osteotomies on bovine rib bones. The amount of the collected bone particle and particle size (<500 μm: small, 500–1000 μm: medium, and >1000 μm: large) were measured. Total wet (1.535 ± 0.232 mL) and dry volume (1.147 ± 0.425 mL) of the bone particles from bone harvesting device were significantly greater than three drill systems (wet volume: 1.225 ± 0.187–1.27 ± 0.29 mL and dry volume: 0.688 ± 0.163–0.74 ± 0.311 mL) (P < 0.05). In all groups, the amount of large sized particles in wet and dry state was the greatest compared to that of medium and small particles. The dry weight of the bone particles showed the same tendency to volumetric measurement. In conclusion, total bone particles and large sized particles (>1000 μm) were harvested significantly greater by bone harvesting device than minimally irrigated low-speed drilling. The composition of particle size in all harvesting methods was similar to each other.

Clinical efficacy of grafting materials in alveolar ridge augmentation: A systematic review

PURPOSE

To evaluate the efficacy of grafting materials in lateral and vertical ridge augmentations.

MATERIALS AND METHODS

A systematic review of the literature on the clinical use of grafting materials of the years 1995 to April 2015 was conducted using electronic search of PubMed and Cochrane libraries and hand search of eight print journals. A total of 184 papers were included, comprising 6182 patients. Parameters evaluated were observation period [months], bone formation [histologic area%], defect fill [%], horizontal and vertical gain [mm], loss of augmented volume [mm], complication rate [%], and implant survival rate [%]. Results are expressed as weighted means ± SD.

RESULTS

Results were obtained after a weighted mean observation period of 27.4 months (range 3-168 months). Bone formation in the augmented areas varied from 33.2 ± 14.9% for allogeneic grafts to 56.0 ± 25.6% for mixtures of autogenous and other grafting materials. Defect fill in dehiscence defects ranged from 51.0 ± 13.6% (synthetic) to 85.8 ± 13.4% (xenogeneic) for the different materials, with an overall weighted mean of 79.8 ± 18.7%. Weighted mean horizontal gain for all particulate grafting materials was 3.7 ± 1.2 mm, with variation between 2.2 ± 1.2 mm (synthetic) and 4.5 ± 1.0 mm (mixtures of autogenous bone with allogeneic/xenogeneic grafting material) without statistical significance. Weighted overall mean vertical gain was 3.7 ± 1.4 mm. Vertical gain was substantially higher when space-making barrier materials such as titanium meshes were used; however this was also associated with strong increase in complication rate. Block grafts achieved higher horizontal gain by approximately 1 mm. The use of block grafts achieved significantly increased vertical gain compared to particulate material only when autogenous block grafts from extraoral donor sites were used.

CONCLUSION

Horizontal and vertical gain by 3.7 mm on average can be achieved using particulate materials. This can be increased by using titanium meshes. Substantial vertical gains beyond this dimension require the use of extraoral bone block grafts.

Effectiveness of Lateral Bone Augmentation on the Alveolar Crest Dimension

Lateral ridge augmentation procedures are aimed to reconstruct deficient alveolar ridges or to build up peri-implant dehiscence and fenestrations. The objective of this systematic review was to assess the efficacy of these interventions by analyzing data from 40 clinical studies evaluating bone augmentation through either the staged or the simultaneous approach. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guideline for systematic reviews was used. The primary outcomes were the changes at reentry, in the ridge width, and in the vertical and horizontal dimensions of the peri-implant defect, measured in millimeters, in the staged and simultaneous approaches, respectively. The results of the meta-analysis showed, for the simultaneous approach, a statistically significant defect height reduction when all treatments were analyzed together (weighted mean difference [WMD] = −4.28 mm; 95% confidence interval: [CI] –4.88, –3.69; P < 0.01). The intervention combining bone replacement grafts with barrier membranes was associated with superior outcomes The most frequently used intervention was the combination of xenograft and bioabsorbable membrane. Similarly, for the staged approach, there was a statistically significant horizontal gain when all treatment groups were combined (WMD = 3.90 mm; 95% CI: 3.52, 4.28; P < 0.001). The most frequently used intervention was the use of autogenous bone blocks. Both treatment strategies led to high survival and success rates (>95%) for the implants placed on the regenerated sites. Nonexposed sites gained significantly more in the simultaneous and staged approaches (WMD = 1.1 and 3.1 mm).

Impact of bone graft harvesting techniques on bone formation and graft resorption: a histomorphometric study in the mandibles of minipigs

BACKGROUND

Harvesting techniques can affect cellular parameters of autogenous bone grafts in vitro. Whether these differences translate to in vivo bone formation, however, remains unknown.

OBJECTIVE

The purpose of this study was to assess the impact of different harvesting techniques on bone formation and graft resorption in vivo.

MATERIAL AND METHODS

Four harvesting techniques were used: (i) corticocancellous blocks particulated by a bone mill; (ii) bone scraper; (iii) piezosurgery; and (iv) bone slurry collected from a filter device upon drilling. The grafts were placed into bone defects in the mandibles of 12 minipigs. The animals were sacrificed after 1, 2, 4 and 8 weeks of healing. Histology and histomorphometrical analyses were performed to assess bone formation and graft resorption. An explorative statistical analysis was performed.

RESULTS

The amount of new bone increased, while the amount of residual bone decreased over time with all harvesting techniques. At all given time points, no significant advantage of any harvesting technique on bone formation was observed. The harvesting technique, however, affected bone formation and the amount of residual graft within the overall healing period. Friedman test revealed an impact of the harvesting technique on residual bone graft after 2 and 4 weeks. At the later time point, post hoc testing showed more newly formed bone in association with bone graft processed by bone mill than harvested by bone scraper and piezosurgery.

CONCLUSIONS

Transplantation of autogenous bone particles harvested with four techniques in the present model resulted in moderate differences in terms of bone formation and graft resorption.

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

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

Effect of clinical factors on bacterial contamination of bone chips collected during implant surgery

PURPOSE

The objective of this study was to investigate the relationship between various clinical factors and bacterial contamination of bone chips (BC) collected during dental implant surgery and to elucidate how bacterial contamination might be minimized.

MATERIALS AND METHODS

Implants were installed in 55 partially edentulous patients (36 men and 19 women), among whom the relationship between various clinical factors and bacterial contamination of BC collected by bone trap was investigated in 37. The effect of rinsing with a saline on BC was determined in 18 patients. Number of contaminating microorganisms was expressed as colony-forming units (CFUs).

RESULTS

CFUs in the maxilla were lower than those in the mandible (P < 0.01). CFUs at the incisors or canines were lower than those at the premolars or molars (P < 0.01). Logistic regression analysis revealed a relationship between average bacterial count and duration of surgery (odds ratio, 1.046; 95% CI, 1.012-1.081). Rinsing of BC reduced bacterial contamination.

CONCLUSION

Duration of surgery is a major clinical factor affecting contamination risk in BC, and rinsing of BC with a sterile saline solution reduces bacterial number.

Implant treatment choice after extraction of a vertically fractured tooth. A proposal for a clinical classification of bony defects based on a systematic review of literature

OBJECTIVES

The objectives of this study were to propose a classification for the bone defects resulting after extraction of a vertically fractured tooth and to review the existing literature about the treatment of such kind of defects by means of dental implants in combination with regenerative procedures.

MATERIALS AND METHODS

An electronic search was performed on biomedical databases using a combination of appropriated search terms combined through the use of Boolean operators. All articles concerning the treatment of peri-implant bone dehiscences and fenestrations through guided bone regeneration (GBR) with at least 6 months follow-up were eligible. Outcomes data extracted from the selected articles were summarized using descriptive tables. A classification of the bone defects associated with vertical root fracture (VRF) was also proposed.

RESULTS

A total of 33 articles were included in the review. Twenty-three articles (814 implants) were about bone dehiscence treatment, ten articles presented the treatment of fenestrations, and ten (429 implants) adopted vertical bone augmentation. The percentage of bone filling was variable among different procedures and defect classification. The use of resorbable membrane was associated with better outcomes than the use of non-resorbable ones.

CONCLUSIONS

Guided bone regeneration for the management of bone defects in the presence of a VRF of the extracted tooth is a viable treatment option. The assessment of bone defect geometry prior to a tooth extraction could be clinically relevant for evaluating the feasibility and the success of immediate implant placement as well as the need of GBR.

Mastoid bone as a new graft material in rhinoplasty

BACKGROUND

The management of certain nasal deformities, especially after prior rhinoplasty, may require grafting material. In this study we describe the use of mastoid bone as a viable and low morbidity autologous graft.

METHODS

Mastoid bone was used for nasal augmentation, smoothing dorsal nasal irregularities, or augmentation of radix. Candidates for mastoid bone graft were patients undergoing primary rhinoplasty suffering from low radix or saddle nose deformity and candidates for secondary rhinoplasty suffering from prior overresection of the osteocartilaginous structures.

RESULTS

Fifty-six patients met the study criteria. Eighteen patients underwent secondary rhinoplasty and suffered from prior overresection of osteocartilaginous structures and 38 patients underwent primary rhinoplasty. Of these, 18 patients had a low radix and 20 patients had a saddle nose deformity. Follow-up was 6-49 months (mean, 23 months). All cases resulted in an augmented straightened nasal dorsum, increased tip projection, and adjusted radix. There were no cases of graft infection. In two cases the graft was displaced requiring revision. The amount of graft absorption even after 2 years follow-up was acceptable. There were no donor site complications.

CONCLUSIONS

The mastoid bone graft provides adequate autologous bone in most cases of primary or revision rhinoplasty. The donor site carries low morbidity and a well camouflaged scar. It is easily accessible especially for the otolaryngologist who is accustomed to operating on the mastoid bone.

A novel bone scraper for intraoral harvesting: a device for filling small bone defects

AIM

To evaluate histologically the morphology and characteristics of bone chips harvested intraorally by Safescraper, a specially designed cortical bone collector.

MATERIAL AND METHODS

Bone chips harvested near a bone defect or in other intraoral sites were grafted into a post-extractive socket or applied in procedures for maxillary sinus floor augmentation or guided bone regeneration. Core biopsies were performed at implant insertion. Undecalcified specimens embedded in PMMA were studied by histology, histochemistry and SEM.

RESULTS

Intraoral harvesting by Safescraper provided a simple, clinically effective regenerative procedure with low morbidity for collecting cortical bone chips (0.9-1.7 mm in length, roughly 100 microm thick). Chips had an oblong or quadrangular shape and contained live osteocytes (mean viability: 45-72%). Bone chip grafting produced newly formed bone tissue suitable for implant insertion. Trabecular bone volume measured on biopsies decreased with time (from 45-55% to 23%). Grafted chips made up 50% or less of the calcified tissue in biopsies. Biopsies presented remodeling activities, new bone formation by apposition and live osteocytes (35% or higher).

DISCUSSION AND CONCLUSIONS

In conclusion, Safescraper is capable of collecting adequate amounts of cortical bone chips from different intraoral sites. The procedure is effective for treating alveolar defects for endosseous implant insertion and provides good healing of small bone defects after grafting with bone chips. The study indicates that Safescraper is a very useful device for in-office bone harvesting procedures in routine peri-implant bone regeneration.

Preservation of the Gingival Architecture With the Scalloped Implant Design: A Clinical Report

Replacing the missing maxillary anterior teeth with dental implants and maintaining the soft tissue structure and alveolar profile is an esthetic challenge for the restorative dentist. This clinical report describes the immediate provisional placement and prosthetic rehabilitation of 2 missing maxillary central incisors with scalloped dental implants.

Performance of six bone collectors designed for dental implant surgery

OBJECTIVES

The aim of this study was to perform an in vitro comparison of six bone collectors for harvesting of particulate bone.

MATERIAL AND METHODS

Four commercially available bone collectors (Frios, Osseous Coagulum Trap, ACE Autografter, Bone Trap) and two custom-designed models were tested. Three different in vitro tests were performed to determine the harvesting capabilities of the collectors. In test I, a bovine mandible was drilled and the bone collectors were used to collect bone chips. The harvested bone volumes and dry weights were measured after harvesting. In test II, three dental implant sites were prepared in a bovine mandible. The bones from the implant osteotomies were collected, and bone volumes and dry weights were measured. In test III, 1 ml of bone chips was mixed with water, and suctioned through the bone collectors. The volumes of the bone chips retained were measured to determine the efficiency of each collector.

RESULTS

The Osseous Coagulum Trap and the custom-made collectors were the most effective instruments in test I. The mean volumes ranged from 0.17 to 0.38 ml. In test II, the difference between the collectors was small and the bone volume ranged from 0.28 to 0.37 ml. In test III, the Bone Trap became blocked before the other collectors, and its bone procurement was therefore limited.

CONCLUSION

Comparison of six different bone collectors in this in vitro study showed that all collectors are usable in clinical situations but their effectiveness varies.

Maxillary sinus and ridge augmentations using a surface-derived autogenous bone graft

PURPOSE

The purpose of this article is to describe a new technique and the anatomic sites for cutting and harvesting bone for grafting applications. A handheld instrument is described that cuts and collects thin shavings of bone from cortical surfaces.

MATERIALS AND METHODS

This study included 193 consecutive patients who needed bone augmentation and simultaneous implant placement in the severely atrophic posterior maxilla and in the anterior maxilla with acquired defect of alveolar bone as a result of local trauma. A total of 477 implants were placed. Clinical criteria for evaluation at time of implant exposure included stability in all directions, crestal bone resorption, and any reported pain of discomfort.

RESULTS

There were no failures of the anterior maxilla group, and no signs of bone resorption were noted at the second stage surgery or during the follow-up. During initial and late healing, there was no dehiscence of the soft tissue flaps and no membranes were exposed. Core biopsies typically showed immature, newly formed bone and, on average, 27% to 36% vital bone.

CONCLUSION

From this research, it appears that excellent implant success rates can be achieved in grafted sinuses or ridges when a locally harvested autogenous bone graft with a ribbon geometry is used.

Bone chips and diced cartilage: an anatomically adopted graft for the nasal dorsum

Since 1996, cranial bone chips or septal bone chips harvested during septal deviation surgery and small chips of ear or septal cartilage have been used in 67 patients for dorsal nasal augmentation or for smoothing dorsal nasal irregularities. In this study, 59 overresections of ostecartilaginous nose structures during previous aesthetic nose surgeries and 8 primary rhinoplasties occasioned the use of bone or cartilage grafts. For 57 patients both bone and ear cartilage grafts were used for the reconstruction. Bone grafts were used for seven cases and cartilage grafts for three cases. The results from 7 years, of experience with this method of nasal dorsum reconstruction were satisfactory and durable. The most important advantage of this method is that the bony side of the nose is reconstructed with bone and the cartilage side with cartilage. Another advantage is that the bone chips are incorporated with both nasal bones, building a strong dorsal nasal bony mono-black. This technique also is useful for augmenting mild saddle nose deformity and dorsal nasal projection deficiency on the bony part, cartilage part, or both parts.