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

OBJECTIVES: To evaluate the sequential osseointegration of a novel titanium implant system based on a 3D printing technology in comparison with conventional titanium implants. MATERIAL AND METHODS: Two novel titanium implants based on 3D printing were tested in the mandible of eight Beagle dogs. As a control, two different commercially available titanium implants were used. The implants were staged to accommodate healing periods of 2 and 6 weeks. The primary outcome variable was bone-to-implant contact (BIC) in non-decalcified tissue sections and micro-CT analysis. RESULTS: Histomorphometrically, the proportions of tissues adjacent to the implant surfaces were similar for all implants, whereas the BIC percentage of new mineralized bone was greater for the control implants after both 2 and 6 weeks (p < .05). Micro-CT analysis revealed increasing osseous volume and BIC from 2 to 6 weeks. In contrast to the histomorphometry, the BIC evaluation with the micro-CT data revealed a significantly higher BIC for the two test implants compared with controls (p < .001). The analysis of the total implant surface area disclosed a value that was approximately double as high for the test compared to the control implants. CONCLUSIONS: The novel titanium implant system based on 3D printing yielded values for osseointegration that were adequate and satisfactory. The higher percentage of new mineralized bone in the control implants is explained by the fact of a completely different three-dimensional surface area.

Retention of teeth in the fracture gaps of the mandible: a retrospective analysis.

OBJECTIVES: Since the introduction of miniplate osteosynthesis and the use of prophylactic antibiotics, the complication rate related to the teeth in the fracture gap has significantly decreased. Currently, there are still no established guidelines for the management of such teeth in mandibular fracture lines. However, the long-term viability of these teeth within the fracture gap remains uncertain. Therefore, this study aimed to assess the survival rate of teeth located within the mandibular fracture line and evaluate related follow-up treatments over a minimum period of one year. MATERIALS AND METHODS: This retrospective study examined 184 patients who underwent surgical treatment for mandibular fractures between January 2018 and December 2021. A total of 189 teeth located in the fracture line were analyzed. Clinical and radiological parameters were collected, including patient age and gender, fracture etiology and location, intraoperative tooth treatment, as well as complications related to both the fracture and the affected teeth in long term. RESULTS: Most of the examined teeth remained uneventful, with postoperative tooth-related complications seen in 14 (7.4%) teeth. The most common complications were symptomatic apical periodontitis (n = 9, 4.8%) and increased tooth mobility (n = 3, 1.5%). A correlation was found between complications and trauma-related tooth luxation (p = 0.002, OR = 15.2), as well as prior teeth connected to retainers or orthodontic appliances (p = 0.001, OR = 10.32). CONCLUSION: Tooth-related complications are rare when intact teeth are retained within the fracture gap. Therefore, unless there is a definitive intraoperative indication for extraction, it is recommended to preserve the teeth in the fracture line. CLINICAL RELEVANCE: Intact teeth in the fracture line of the mandible should not be primarily extracted.

Implant Placement Using the Bone Ring Technique With and Without Membrane Placement: A Preclinical 12-Month Study in Dogs.

The bone ring technique is applied for vertical augmentation, in which the dental implant and autogenous block bone graft are simultaneously inserted. We investigated the healing of bone around implants placed simultaneously using the bone ring technique with and without membrane placement after a 12-month healing period. Vertical bone defects were created on both sides of the mandible of Beagle dogs. Implants were inserted into the defects through bone rings and fixed with membrane screws as healing caps. The augmented sites on one side of the mandible were covered with a collagen membrane. Samples were harvested 12 months after implantation and assessed histologically and by microcomputed tomography analysis. All implants remained throughout the healing period; however, except for 1 implant, they showed lost caps and/or exposure to the oral cavity. The implants had contact with newly formed bone despite frequent bone resorption. The surrounding bone appeared mature. The medians of bone volume and percentages of total bone area and bone-to-implant contact within the bone ring were slightly higher in the group with membrane placement than in that without membrane placement. Nevertheless, none of the evaluated parameters were significantly affected by the membrane placement. In the present model, soft tissue complication was frequent, and the membrane application did not reveal the effect at 12 months after implant placement using the bone ring technique. Sustained osseointegration and maturation of surrounding bone were observed in both groups after a 12-month healing period.

Pumping the Periosteum: A Feasibility Study.

PURPOSE: Gradual elevation of periosteum from the bone surface is known to promote the adaptation of soft tissues and the formation of hard tissues. The aim of our study was to estimate the benefit of periosteal distraction osteogenesis (PDO) on de novo bone formation in a rat model. MATERIALS AND METHODS: After device placement, animals were allowed for a latency period of 7 days. Animals in the PDO group were subjected to distraction at a rate of 0.1 mm/d for 10 days. In the periosteal pumping (PP) group, the animals were subjected to distraction at a rate of 0.1 mm/d. The direction of distraction was alternated every 2 days. The animals were euthanized at 17, 31, and 45 days after surgery, and the samples were analyzed histologically and by microcomputed tomography. RESULTS: In both groups, the new bone was characterized as primary woven bone that was located at the leading edge of bone apposition. Bone volumes significantly increased throughout the observation period both in the PP group ( P = 0.018) and in the PDO group ( P < 0.001). The new bone was denser and more mature in the PP group than in the PDO group, and the difference was significant at the 31-day time point ( P = 0.024). However, the volume of the new bone was higher in the PDO at the 45-day time point ( P < 0.001). CONCLUSIONS: We propose that the PP may be applied to enhance the osteogenic capacity of periosteum without plate elevation. Because this is only a proof-of-principle study, the alternated protocol of periosteal distraction warrants evaluation in the future studies.

No apparent association between dental implants and mandibular fractures resulting from external forces.

OBJECTIVES: Dental implants are cylindrical metallic screws inserted into the jawbone to replace missing teeth. Their location may affect the pattern of fractures that occur as a result of the traumatic forces to the mandible. The aim of this study was to investigate possible influences of dental implants on the patterns of mandibular fractures triggered by external forces. MATERIAL AND METHODS: In this observational cross-sectional study, a total of 390 patients with mandibular fractures diagnosed between February 2016 and December 2020 were examined and the presence or absence of dental implants in the fracture gap was noted. Clinical and radiological data were analyzed in relation to the fracture line, the dental status, and the location of any implants. RESULTS: A total of 16 patients (4.1%) had previously placed dental implants in the mandible. Various fracture patterns were observed. Some yielded typical fracture lines located in the anatomically weak areas along the roots of the incisors, the mental foramina, and long-rooted molars. Occasionally, fracture lines were detected in combination with condylar fractures. Dental implants were not directly involved in any fracture line, except one. In that case, the fracture line extended from the alveolar process straight along the implant body, mimicking initial disintegration of the implant, with erosion of the surrounding bone. CONCLUSIONS: Once dental implants have osseointegrated, mandibular fractures are rarely projected along the implant surface. CLINICAL RELEVANCE: This observational retrospective cross-sectional study failed to associate mandibular fracture lines with the presence of dental implants.

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.

Pre-clinical evaluation of the effect of a volume-stable collagen matrix on periodontal regeneration in two-wall intrabony defects.

AIM: To histologically evaluate the effect of a new collagen matrix on periodontal regeneration. MATERIALS AND METHODS: Two-wall intrabony defects were surgically created bilaterally distally to the maxillary first and third pre-molars in beagle dogs. The defects were randomly allocated to open flap debridement either with (test) or without (control) a volume-stable collagen matrix (VCMX). After 12 weeks, the dogs were euthanized, and the specimens histologically processed. Descriptive, histomorphometrical (vertical gain of periodontal tissues) and statistical analyses were then performed. RESULTS: Healing was uneventful in most cases. Residual VCMX was still present and showed integration into new bone, new periodontal ligament, connective tissue and, in some specimens, into new cementum. Periodontal regeneration occurred to a varying extent in both groups. New continuous cementum and new bone formation were statistically significantly greater in the test group (4.12 mm and 3.28 mm, respectively) than in the control group (1.54 mm and 2.47 mm, respectively) (p = .009 and p = .037, respectively). The junctional epithelium was longer in the control group (2.21 mm) than in the test group (1.49 mm, p = .16). CONCLUSION: The present results have for the first time provided histologic evidence for the potential of this novel VCMX to facilitate periodontal regeneration thus warranting further pre-clinical and clinical testing.

The effect of synthetic bone graft substitutes on bone formation in rabbit calvarial defects.

The aim of this study was to evaluate the influence of the intensity of the biomimetic hydroxyapatite (HA) coating of α-tricalcium phosphate (α-TCP) on biomaterial degradation and bone formation. Twenty-four female NZW rabbits of approximately 12 weeks of age were used. Critical size defects were randomly treated with 3%:97% HA:α-TCP (BBCP1), 12%:88% HA:α-TCP (BBCP2), and 23%:77% HA:α-TCP (BBCP3), respectively or sham. All defects were covered with a resorbable collagen membrane. Animals were euthanized after 3 and 12 weeks of healing and samples were investigated by micro-CT and histologic analysis. Ingrowth of newly formed woven bone from the original bone at 3-week healing period was observed in all samples. At the 12-week healing period, the new bone in the peripheral area was mainly lamellar and in the central region composed of both woven and lamellar bone. New bony tissue was found on the surface of all three types of granules and at the interior of the BBCP1 granules. Samples with 3% HA showed significantly less residual biomaterial in comparison to the other two groups. Furthermore, BBCP1 significantly promoted new bone area as compared to other three groups and more bone volume as compared to the control. Within its limitations, this study indicated the highest degradation rate in case of BBCP1 concomitant with the highest rate of bone formation. Hence, formation of new bone can be affected by the level of biomimetic HA coating of α-TCP.

Immunohistochemical Evaluation of Periodontal Regeneration Using a Porous Collagen Scaffold.

(1) Aim: To immunohistochemically evaluate the effect of a volume-stable collagen scaffold (VCMX) on periodontal regeneration. (2) Methods: In eight beagle dogs, acute two-wall intrabony defects were treated with open flap debridement either with VCMX (test) or without (control). After 12 weeks, eight defects out of four animals were processed for paraffin histology and immunohistochemistry. (3) Results: All defects (four test + four control) revealed periodontal regeneration with cementum and bone formation. VCMX remnants were integrated in bone, periodontal ligament (PDL), and cementum. No differences in immunohistochemical labeling patterns were observed between test and control sites. New bone and cementum were labeled for bone sialoprotein, while the regenerated PDL was labeled for periostin and collagen type 1. Cytokeratin-positive epithelial cell rests of Malassez were detected in 50% of the defects. The regenerated PDL demonstrated a larger blood vessel area at the test (14.48% ± 3.52%) than at control sites (8.04% ± 1.85%, p = 0.0007). The number of blood vessels was higher in the regenerated PDL (test + control) compared to the pristine one (p = 0.012). The cell proliferative index was not statistically significantly different in pristine and regenerated PDL. (4) Conclusions: The data suggest a positive effect of VCMX on angiogenesis and an equally high cell turnover in the regenerated and pristine PDL. This VCMX supported periodontal regeneration in intrabony defects.

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

OBJECTIVES: To assess the impact of collagen membrane application on bone formation surrounding implants placed simultaneously with the bone ring technique. MATERIAL AND METHODS: Dental implants were inserted simultaneously with the bone ring technique in standardized, vertical alveolar bony defects in the mandible of dogs. On one side of the mandible, the augmented sites were covered with a collagen membrane (M-Group). On the contralateral side, no membranes were used (NM-Group). Implants were left to heal with osseointegration for three and six months. The harvested samples were analyzed by means of micro-CT. RESULTS: A nonparametric analysis of data revealed that the membranes were not a significant negative factor for bone volume (BV), but for bone-to-implant contact (BIC, p = .04). Absence of healing caps impaired BV (p = .04) and BIC (p = .02) as well. Furthermore, loss of healing caps and exposure to the oral environment significantly and negatively affected BV (p < .001) and bone mineral density (p < .05) within 2 mm below the implant shoulder. Implant exposure and healing time had a negative interaction effect on both BV (p = .01) and BIC (p = .01). CONCLUSIONS: Within its limitations, the present study revealed no benefit of membrane application to implant placement simultaneous with the bone ring technique. Disruption of soft tissue healing was identified as a risk factor for decrease in BV and BIC.

Effects of local application of alendronate on early healing of extraction socket in dogs.

OBJECTIVE: The aim of the present study was to assess the effects of alendronate (ALN) on bone remodeling following tooth extraction in a dog model. MATERIAL AND METHODS: For the study, fifteen male Beagles dogs of approximately 12 months of age were used. Mesial roots of four mandibular premolars were endodontically treated, and the distal roots were removed. ALN concentrations of 0.5, 1, and 2 mg/mL were topically applied for 15 min, while a sterile saline was used as a negative control. After the healing period of 1, 2, and 8 weeks, the samples were analyzed by micro-CT and histology. RESULTS: Treatment with ALN increased vertical distance between the lingual and the buccal crestal bones. While the ALN-treated sockets had preserved more lingual bone areas, control sockets showed better preservation of the buccal bone areas. ALN treatment resulted in more osteoid formation within the extraction sockets compared with the control. Higher bone volume was found in ALN groups than in the control at 2-week and 8-week healing periods, reaching the significant difference only for the extraction sockets pooled for the ALN treatment. CONCLUSIONS: Although ALN treatment could not prevent buccal bone resorption following tooth extraction in dogs, it proved beneficial for the preservation of the lingual bone and formation of new bone within the socket. There was no clear relation between the ALN dosages and the alterations within the extraction sockets. CLINICAL RELEVANCE: ALN affects bone remodeling of the extraction socket. The optimal concentration remains to be determined in future studies.

Effects of additional collagen in biphasic calcium phosphates: a study in a rabbit calvaria.

OBJECTIVES: Biphasic calcium phosphates (BCP) are synthetic biomaterials developed as an alternative to the autogenous bone grafts and xenografts. The aim of the present study was to assess the influence of the addition of collagen onto the BCP resorption rate and bone formation. MATERIAL AND METHODS: Eighteen male NWZ rabbits approximately 12 weeks of age were used. Critical size defects were randomly treated with bilayered BCP materials comprising 12% HA and 88% α-TCP with and without collagen or sham-operated, respectively. All defects were covered with a resorbable collagen membrane. Animals were euthanized after 3 and 12 weeks of healing and investigated by micro-CT, histologic, and histomorphometric analysis. RESULTS: Woven bone formation was observed from the original bone at 3-week healing in all samples. After 3 months, mainly lamellar new bone in the peripheral area was observed. In the central region, both woven and lamellar bone were seen. Samples containing collagen showed less residual biomaterial than without collagen at both healing periods. Both types of granules were in close contact with new bone, yielding a complete defect closure at 3 months of healing. However, new bone volume and area was similar for both biomaterials. CONCLUSIONS: Within its limitations, the study results qualify collagen as a biocompatible carrier for BCPs. The presence of collagen indicated neither significant impact on the resorption of the BCPs nor on bone formation. CLINICAL RELEVANCE: The addition of collagen to BCPs might not be beneficial for the augmentation of extended bone deficiencies.

Use of platelet-rich fibrin for the treatment of gingival recessions: a systematic review and meta-analysis.

OBJECTIVES: The aim of this systematic review and meta-analysis was to compare the use of platelet-rich fibrin (PRF) with other commonly utilized treatment modalities for root coverage procedures. MATERIALS AND METHODS: The eligibility criteria comprised randomized controlled trials (RCTs) comparing the performance of PRF with that of other modalities in the treatment of Miller class I or II (Cairo RT I) gingival recessions. Studies were classified into 5 categories as follows: (1) coronally advanced flap (CAF) alone vs CAF/PRF, (2) CAF/connective tissue graft (CAF/CTG) vs CAF/PRF, (3) CAF/enamel matrix derivative (CAF/EMD) vs CAF/PRF, (4) CAF/amnion membrane (CAF/AM) vs CAF/PRF, and (5) CAF/CTG vs CAF/CTG/PRF. Studies were evaluated for percentage of relative root coverage (rRC; primary outcome), clinical attachment level (CAL), keratinized mucosa width (KMW), and probing depth (PD) (secondary outcomes). RESULTS: From 976 articles identified, 17 RCTs were included. The use of PRF statistically significantly increased rRC and CAL compared with CAF alone. No change in KMW or reduction in PD was reported. Compared with PRF, CTG resulted in statistically significantly better KMW and RC. No statistically significant differences were reported between the CAF/PRF and CAF/EMD groups or between the CAF/PRF and CAF/AM groups for any of the investigated parameters. CONCLUSIONS: The use of CAF/PRF improved rRC and CAL compared with the use of CAF alone. While similar outcomes were observed between CAF/PRF and CAF/CTG for CAL and PD change, the latter group led to statistically significantly better outcomes in terms of rRC and KTW. In summary, the use of PRF in conjunction with CAF may represent a valid treatment modality for gingival recessions exhibiting adequate baseline KMW. CLINICAL RELEVANCE: The data indicate that the use of PRF in conjunction with CAF statistically significantly improves rRC when compared with CAF alone but did not improve KMW. Therefore, in cases with limited baseline KMW, the use of CTG may be preferred over PRF.

Effect of enamel matrix derivative liquid in combination with a natural bone mineral on new bone formation in a rabbit GBR model.

OBJECTIVES: Recently, a new liquid carrier system for enamel matrix derivate (EMD-liquid) was developed with better physico-chemical properties for improved adsorption of EMD to biomaterial surfaces. The aim of the present study was to investigate the bone regenerative potential of EMD-liquid in combination with a natural bone mineral (NBM) in vivo. METHODS: Four 6-mm defects were created in the calvaria of six New Zealand white rabbits. Defects were filled with either (1) control (empty), (2) 20 mg of NBM, or (3) 20 mg of NBM + 20 µl of EMD-liquid (n = 8). All defects were covered with collagen barrier membranes. The bone regenerative potential was investigated by micro-CT and histomorphological analyses at 8 weeks postsurgery. RESULTS: The mineralized tissue volume was significantly higher in the NBM + EMD-liquid group when compared to control, whereas no difference was observed between the NBM alone and control groups. While no significant difference was observed for horizontal bone defect closure between the NBM + EMD-liquid and the NBM alone groups, NBM + EMD-liquid significantly increased the total mineralized area and reduced the percentage of soft/connective tissue infiltration. No statistically significant difference was observed between the NBM + EMD-liquid group and NBM alone group for amount of mineralized bone. CONCLUSION: The addition of EMD-liquid did not lead to statistically significant bone formation when compared to NBM alone. The combination of NBM + EMD-liquid but not NBM alone did however induce superior mineralized tissues when compared to control (empty). Further research investigating the adsorption potential of EMD-liquid to bone-grafting particles with/without collagen may provide valuable insights into future regenerative strategies with enamel matrix proteins.

Single-staged implant placement using bone ring technique with and without membrane placement: An experimental study in the Beagle dog.

AIM: To evaluate the impact of a collagen membrane on bone remodeling and osseointegration of implants placed simultaneously with a bone ring technique. MATERIAL AND METHODS: Standardized, vertical alveolar bone defects in the mandibles of six dogs were created. Tapered dental implants designed for two-stage subcrestal placement were inserted simultaneously with a bone ring technique. On one side of the mandible, the augmented sites were covered with a collagenous membrane. Implants with (M Group) and without membranes (NM Group) were left for an osseointegration period of 3 and 6 months, respectively. Block biopsies of the implants with surrounding bone were harvested and analyzed histologically. RESULTS: Implant exposure was a common finding (2/3) concomitantly with loss of healing caps. It appeared to be related to advanced bone loss around the implants. Exposure of implants was more frequent in M Group, however, without significant differences when compared to NM Group. The total bone area within the region of the bone ring was greater in the NM Group compared to the M Group. Moreover, in the region of the pristine bone of the M Group, the total bone was greater than at the corresponding NM Group sites at both observation periods. A nonparametric analysis of variance (ANOVA) revealed no significant effects of membrane placement or healing period on the total area of the bone. The total bone-to-implant contact (BIC) for the two groups was similar at each observation time point. However, BIC increased significantly at 6-month compared with 3-month observation period (p = .0088) in both groups. CONCLUSIONS: In vertical bone augmentation applying the bone ring technique, the disruption of soft tissue was a frequent complication. Membrane placement yielded no significant advantage on the osseointegration (BIC) of implants or bone characteristics.

Recombinant human BMP9 (RhBMP9) in comparison with rhBMP2 for ridge augmentation following tooth extraction: An experimental study in the Beagle dog.

OBJECTIVES: The purpose of this study was to compare the effects of rhBMP2 with rhBMP9 on ridge augmentation following healing of extraction sockets in dogs. MATERIAL AND METHODS: Five male Beagle dogs, approximately 12 months of age, were used. The mesial roots of the four maxillary premolars were endodontically treated. The distal roots were extracted, and the buccal bony walls removed. All extraction sockets were filled with deproteinized bovine bone mineral (DBBM). A collagen membrane was soaked with 4 µg or 20 µg of rhBMP9, 20 µg of rhBMP2 or sterile saline and placed over the augmented sites. All animals were euthanized after 8 weeks of healing and investigated by micro-CT and histologic analysis. A one-way ANOVA with Tukey's HSD post hoc test was used to compare the differences between the four groups. RESULTS: New bone apposition in all defects was observed from the original bone. RhBMP samples showed an increase in bone formation in the buccal area and better integration of DBBM particles when compared to control sites. Both rhBMP9 defects showed higher values of bone (p = 0.024), bone marrow (p = 0.044), and total augmentation volume (p = 0.033) than the rhBMP2 (20 µg) or control sites. Highest bone area was found in rhBMP9 defects (p = 0.895). CONCLUSIONS: Within the limitations of the present study, rhBMP9 sites demonstrated higher bone-inducing potential in combination with DBBM than rhBMP2. While rhBMP9s failed to demonstrate a clear dose-response relationship to the outcomes, future studies are necessary to evaluate the appropriate dose and carrier systems.

Comparison of three block bone substitutes for bone regeneration: long-term observation in the beagle dog.

This study aimed to evaluate the impact of three types of block bone substitute material on bone formation and graft resorption in vivo. Standardized bone defects (n = 4 defects/animal) were created in the calvaria of nine dogs. Block bone substitutes made of deproteinized bovine bone mineral (DBBM), beta-tricalcium phosphate (ß-TCP) and a mixture alpha-TCP and hydroxyapatite (α-TCP/HA) were inserted into the bone defects. A fourth defect was left untreated (empty). All sites were covered with a collagenous membrane. Block biopsies were harvested at 3, 6 and 12 months post-implantation and analyzed by micro-CT and histology. Biomaterial absorption was minimal and incorporation within the defect margin was good for all biomaterials. However, ß-TCP demonstrated a relatively greater volume of new bone formation and less residual material volume when compared with DBBM and α-TCP/HA. Conversely, α-TCP/HA showed higher osteoconductive potential and a greater new bone area compared with the other two biomaterials. The block bone substitutes used in the present in vivo study showed advantageous in terms of maintenance of their original form in bony defect. However, the positive impact of all biomaterials on new bone formation and replacement of bone was minor even at 12 months. These findings indicate that block bone substitutes are not well suited to vertical bone augmentation. Further investigations are required to improve the insufficient new bone volume for promising clinical results.

Single-staged vs. two-staged implant placement in vertically deficient alveolar ridges using bone ring technique - Part 2: implant osseointegration.

OBJECTIVES: The aim of this study was to evaluate the osseointegration of implants placed in a single-staged compared to two-staged procedure using bone ring technique. MATERIAL AND METHODS: In this study were used standardized, vertical alveolar bone defects in dogs. In the test group, dental implants (Straumann BL® , Basel, Switzerland) were inserted simultaneously with bone ring technique. As control group served implants inserted 6 months following grafting. Implants of both groups were left for an osseointegration period of 3 and 6 months. The peri-implant bone loss and bone-to-implant contact within the bone ring and native bone were analyzed morphometrically. An explorative statistical analysis was performed. RESULTS: The peri-implant bone level remained relatively stable within groups and between groups per given time period. Most of bone apposite on the implant surface in two groups was composed of newly formed bone. A nonparametric analysis of variance (ANOVA) revealed no significant advantage for two-staged implant placement for new and total bone, except for residual bone (P = .0084). Furthermore, two groups of implants performed similarly in bone ring and in native bone throughout the observation period. CONCLUSIONS: In terms of osseointegration, both techniques are likely equally efficient in the present defect model. The single-staged implant placement with cortical bone grafts warrants further documentation in clinical studies.

Single-staged vs. two-staged implant placement using bone ring technique in vertically deficient alveolar ridges - Part 1: histomorphometric and micro-CT analysis.

BACKGROUND: Simultaneous implant placement with bone grafting shortens the overall treatment period, but might lead to the peri-implant bone loss or even implant failure. The aim of this study was to compare the single-staged to two-staged implant placement using the bone ring technique. MATERIAL AND METHODS: Four standardized alveolar bone defects were made in the mandibles of nine dogs. Dental implants (Straumann BL® , Basel, Switzerland) were inserted simultaneously with bone ring technique in test group and after 6 months of healing period in control group. Animals of both groups were euthanized at 3 and 6 months of osseointegration period. The harvested samples were analyzed by means of histology and micro-CT. RESULTS: The amount of residual bone decreased while the amount of new bone increased up to 9 months of healing period. All morphometric parameters remained stable between 3 and 6 months of osseointegration period within groups. Per a given time point, median area of residual bone graft was higher in test group and area of new bone in control group. The volume of bone ring was greater in test than in control group, reaching the significance at 6 months of osseointegration period (P = 0.002). CONCLUSIONS: In the present type of bone defect, single-staged implant placement may be potentially useful to shorten an overall treatment period.

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.