Comparative Study on Early Osseointegration of Implants According to Various Drilling Speeds in the Mandible of Dogs.

PURPOSE: This study evaluated the effect of drilling speed on early bone healing in the mandible of dogs. MATERIAL AND METHODS: Six dogs were selected, and mandibular premolars and molars were extracted. After 2 months, 3 hydroxyapatite-surfaced fixtures were implanted with drilling speeds of 50, 800, and 1200 rpm on the right side first and then on the left side after 2 weeks. Implant stability quotient (ISQ) was measured on insertion, after 2 and 4 weeks. RESULTS: Based on the ISQ measurement, the 1200-rpm group showed a higher value than the 50-rpm group at 2 weeks and 4 weeks (P < 0.05). New bone formation around the implant was highest for the 800-rpm group at 2 weeks and the 1200-rpm group at 4 weeks. The bone-implant contact of the superior half of the alveolar bone was highest for the 800-rpm group at 2 weeks and the 1200-rpm group at 4 weeks. There was no statistically significant difference. CONCLUSION: This study suggests that 50, 800, and 1200 rpm are drilling speeds which can expect favorable outcome, yet, higher drilling speed presented overall the best biological responses.

Comparative Study on Osseointegration of Implants After Flap and Flapless Surgery in the Mandible of Dogs.

PURPOSE: The objective of this study was to compare the implant stability and osseointegration of implants using a flap or flapless technique. MATERIAL AND METHODS: Mandibular premolars and molars were extracted from both sides in 6 dogs. After 8 weeks, 4 fixtures were implanted using either a flap or flapless technique. Implant stability quotient was measured on insertion and at 2, 4, and 8 weeks later. The animals were killed while the tissues were histologically analyzed. RESULTS: Implant stability increased for 8 weeks, and no statistically significant differences were observed between the surgical protocols. Bone-implant contact showed 60.27% ± 30.99% for flapless surgery and 59.73% ± 17.12% for flap surgery. And the results of new bone formation area from total area showed 56.07% ± 27.78% for flapless surgery and 57.00% ± 14.66% for flap surgery. There were no statistically significant differences. CONCLUSION: This study showed no significant difference in implant stability as well as osseointegration regardless of flap or flapless technique.

Histomorphometric Analysis of Contaminated Autogenous Tooth Graft Materials After Various Sterilization.

PURPOSE: The purpose of this study was to evaluate histomorphometrically contaminated autogenous tooth graft materials, which were resterilized. MATERIALS AND METHODS: The intentional defects (diameter: 8 mm, depth: 4 mm) were formed around implant fixture on the iliac crest of 6 mongrel dogs. Autogenous tooth graft materials were made by extracted premolars. After the contamination of the tooth materials, graft procedure was performed; no contaminated group (control group), contaminated groups (nonsterilization group [group 1], ethylene oxide [EO] gas group [group 2], and autoclave group [group 3]). The bone-to-implant contact (BIC) and the new bone formation rate (NBFR) were evaluated after sacrifice. RESULTS: The BIC and NBFR of groups 1 and 3 were significantly lower than the control group after 4 weeks. The BIC and NBRF of group 3 were significantly lower than the control group after 8 weeks. However, the BIC and NBRF of group 2 was not significantly different comparing with the control group after 4 and 8 weeks. CONCLUSION: Sterilization using EO gas may be more favorable than high-pressure sterilization in cases the reuse of contaminated autogenous tooth graft materials.

A Comparative Study of Stability After the Installation of 2 Different Surface Types of Implants in the Maxillae of Dogs.

PURPOSE: This study was performed to investigate the histologic and histomorphometric findings of 2 different types of implant. MATERIALS AND METHODS: Resorbable blasting media (RBM) and sandblasted with larger grit and acid etched (SLA) surfaced implants (24 fixtures in each group) were installed in posterior maxilla of dogs. The initial stability was measured using Periotest (Periotest value [PTV]). After 6 or 12 weeks, fixtures with surrounding bone were harvested. RESULTS: The average initial stability of the SLA group (-1.71 ± 2.9) was higher than that of the RBM group (-1.25 ± 3.21), but there was no significant difference. The mean PTV of the RBM surface was higher than the SLA surface at 12 weeks. The average bone-implant contacts were 67.6% ± 16.0% at 6 weeks and 82.7% ± 8.6% at 12 weeks in the SLA group and 69.9% ± 17.6% at 6 weeks and 78.3% ± 9.2% at 12 weeks in the RBM group. CONCLUSION: The SLA and resorbable blasting media (RBM) surface implants demonstrated good stabilities and healing processes of the surrounding bone in the posterior maxilla. Therefore, the two domestic implants could provide predictable clinical results.

Evaluation of bone formation after grafting with deproteinized bovine bone and mineralized allogenic bone.

PURPOSE: The purpose of this study was to evaluate the ability of new bone formation of deproteinized bovine bone (Bio-Oss) and mineralized allogenic bone (Tutoplast). MATERIALS AND METHODS: Sixty rats were divided into control and experimental groups (groups 1 and 2): control group, unfilled control; group 1, Bio-Oss; group 2, Tutoplast, respectively. The animals were killed after 6 and 12 weeks, and newly formed bone was analyzed histomorphometrically. RESULTS: In the control group, some new bone formed in the rim of the defect area. In the group 1, newly formed bone was thinner than the adjacent normal bone, and Bio-Oss particles were observed. In the group 2, showed a pattern of gradual fusion with adjacent bone, as well as particles in some areas, similar to the Bio-Oss-treated group. In the 12-week groups, the amount of new bone formation was significantly higher in the experimental groups than in the control group, and it was significantly higher in group 2 than in group 1. CONCLUSION: Although Tutoplast and Bio-Oss graft materials seem to be useful for bone grafts, Tutoplast showed more active new bone formation than Bio-Oss.

Osteogenic ability according to the decalcified modality of auto-tooth bone grafts in peri-implant defects in dogs.

PURPOSE: The purpose of this study was to evaluate the bone generation capacity of the autotransplantation material with clinical and histological analyses after controlled acid treatment conditions. MATERIAL AND METHODS: Bony defects were formed in the femur. Then, autotransplantation material was grafted after hydroxyapatite-coated implant placement. Experimental groups were classified according to the acid treatment method: 2% H2SO4 (group 1), 2% HCl (group 2), 2% HNO3 (group 3), or 2% ethylenediaminetetraacetic acid (EDTA) (group 4). RESULTS: The new bone formation area and bone-implant contact (BIC) of the autotransplantation materials were measured after 8 weeks. The new bone formation area in experimental groups 2, 3, and 4 were greater than that in the control group (no graft) and in experimental group 1 at 8 weeks, and the BIC of experimental group 4 was greater than that in the control group and in experimental group 1; these differences showed statistical significance (P < 0.05). CONCLUSION: Auto-tooth bone treated with EDTA resulted in more effective bone formation in dogs' femurs than bone treated with other solutions.

Histomorphometric analysis of bone formation in bony defects around implants in adult dogs: a comparison of grafts of low and high heat-treated autogenous tooth ash.

PURPOSE: The purpose of this study was to compare the bone formation of autogenous tooth ash treated with different temperatures. MATERIALS AND METHODS: Heat treatment was rendered by powder after extraction of teeth from dogs. The bony defects were made at iliac and resorbable blast medium surfaced implant placement and bone graft was performed; no bone graft group (control group), low heat-treated tooth ash group (group 1), high heat-treated tooth ash group (group 2). Right side had healing periods of 12 weeks, and the left side had 6 weeks. Histomorphometrical analysis was performed at 12 weeks. RESULTS: The control group had poor bone formation and showed large loose connective tissue. Group 1 displayed good healing and bone formation. Group 2 showed higher rate of bone formation than group 1 and the control group. The high heat-treated tooth ash group showed a statistically significant increase in the rate of bone formation in the early stage. CONCLUSION: The heat-treated autogenous tooth ash powder showed excellent new bone formation. The temperature of heat treatment is an important factor in new bone formation. The high heat treatment was the optimal treatment method for making tooth ash than the low heat treatment.

Clinical evaluation of demineralized bone allograft for sinus lifts in humans: a clinical and histologic study.

PURPOSE: Severe alveolar bony resorption in the edentulous posterior maxilla and pneumatization of the maxillary sinus wall make traditional implant placement impossible in the posterior maxilla. To reconstruct the severely resorbed maxilla for dental implant placement, 1 successful technique is to elevate the maxillary sinus floor using demineralized bone matrix (DBM) grafts. The purpose of this study was to evaluate a histologic and histomorphometric evaluation of DBM grafts in the human maxilla. PATIENTS AND METHODS: Nine months after grafting, at the time of dental implantation, biopsy samples were taken from the grafted areas of 8 patients and were analyzed histologically. RESULTS: All the sinus lifts were successful in the clinical study conducted after implantation. Resorption of the graft materials and new bone formation were observed, and there was direct deposition of bone on the surface of the graft particles. CONCLUSION: The results of this study indicate that limited maxillary sinus lift with DBM graft material is a clinically reliable preimplant procedure.

Biosynthesis of polylactic acid and its copolymers using evolved propionate CoA transferase and PHA synthase.

For the synthesis of polylactic acid (PLA) and its copolymers by one-step fermentation process, heterologous pathways involving Clostridium propionicum propionate CoA transferase (Pct(Cp)) and Pseudomonas sp. MBEL 6-19 polyhydroxyalkanoate (PHA) synthase 1 (PhaC1(Ps6-19)) were introduced into Escherichia coli for the generation of lactyl-CoA endogenously and incorporation of lactyl-CoA into the polymer, respectively. Since the wild-type PhaC1(Ps6-19) did not efficiently accept lactyl-CoA as a substrate, site directed mutagenesis as well as saturation mutagenesis were performed to improve the enzyme. The wild-type Pct(Cp) was not able to efficiently convert lactate to lactyl-CoA and was found to exert inhibitory effect on cell growth, random mutagenesis by error-prone PCR was carried out. By employing engineered PhaC1(Ps6-19) and Pct(Cp), poly(3-hydroxybutyrate-co-lactate), P(3HB-co-LA), containing 20-49 mol% lactate could be produced up to 62 wt% from glucose and 3HB. By controlling the 3HB concentration in the medium, PLA homopolymer and P(3HB-co-LA) containing lactate as a major monomer unit could be synthesized. Also, P(3HB-co-LA) copolymers containing various lactate fractions could be produced from glucose alone by introducing the Cupriavidus necator beta-ketothiolase and acetoacetyl-CoA reductase genes. Fed-batch cultures were performed to produce P(3HB-co-LA) copolymers having 9-64 mol% of lactate, and their molecular weights, thermal properties, and melt flow properties were determined.

Placement of implant after bone graft using J block allograft.

Securing sufficient alveolar bone is important for a successful implant. Alveolar bone should be augmented to adequate height and width for an implant to satisfy the functional, biological, and aesthetic properties. The subjects of this study were 3 patients with severe bone defects caused by either a periodontal disease or a failure of implants on mandibular posterior tooth, mandibular anterior tooth, and maxillary posterior tooth. The shape of the commercial block allograft (Puros J-Block, Zimmer Dental Inc., Carlsbad, CA) was modified to match the shape of the defect, and resorbable membrane (Puros Pericardium Allograft Membrane, Tutogen Medical GmbH, Germany) was used before suturing the soft tissue. The transplant sites were exposed 4 months later to install the implant. The grafted bone was united with the bone tissue to obtain enough alveolar ridge and to install the implants. Bone allograft used in these cases reduced the need to collect autogenous bone in patients with severe alveolar ridge loss.

Histomorphometric analysis of delayed implantation after horizontal distraction osteogenesis of the mandible in dogs.

PURPOSE: Insufficient alveolar width is known to impede successful implantation and is a major obstacle to successful oral reconstruction using intraosseous implants. The aim of this study was to evaluate the osseointegration at implantation after consolidation in distracted narrow alveolar bone. MATERIALS: Three adult mongrel dogs weighing 9 to 10 kg were studied. The lower premolars were extracted and horizontal distraction was performed using a distraction device after 8 weeks. Eight weeks after consolidation period, SLA surface implants were installed. The dogs were killed after 4 weeks implantation. RESULTS: The preoperative and postoperative buccolingual widths of alveolar ridge were 2.7 ± 2.1 mm and 4.8 ± 2.5 mm, respectively. Direct bone contact was achieved, with no significant difference in new bone formation observed between implants placed in the distracted and undistracted bone after 4 weeks. CONCLUSIONS: It was concluded from this study that horizontal distraction is a useful technique in augmenting a narrow alveolar ridge necessary for implant placement.

Comparative study on the osseointegration of implants in dog mandibles according to the implant surface treatment.

OBJECTIVES: This study compared the impact of implant surface treatment on the stability and osseointegration of implants in dog mandibles. MATERIALS AND METHODS: Six adult dogs received a total of 48 implants that were prepared using four different surface treatments; resorbable blast media (RBM), hydroxyapatite (HA), hydrothermal-treated HA, and sand blasting and acid etching (SLA). Implants were installed, and dogs were separated into 2- and 4-week groups. Implant stability was evaluated via Periotest M, Osstell Mentor, and removal torque analyzers. A histomorphometric analysis was also performed. RESULTS: The stability evaluation showed that all groups generally had satisfactory values. The histomorphometric evaluation via a light microscope revealed that the HA surface implant group had the highest ratio of new bone formation on the entire fixture. The hydrothermal-treated HA surface implant group showed a high ratio of bone-to-implant contact in the upper half of the implant area. CONCLUSION: The hydrothermal-treated HA implant improved the bone-to-implant contact ratio on the upper fixture, which increased the implant stability.

Histologic analysis of resorbable blasting media surface implants retrieved from humans: a report of two cases.

The purpose of this study is to evaluate the degree of osseointegration of resorbable blasting media (RBM) surface implants retrieved from humans. Three implants in the mandibular molar region that were surface-treated with RBM were retrieved from two patients. The implants were used to manufacture specimens in order to measure the bone-implant contact (BIC) ratio. The BIC ratios of the three implants were found to be an average of 69.0%±9.1%. In conclusion, that RBM surface implants are integrated into the host environment with histological significance and the BIC ratio of the RBM surface-treated implant was not significantly different from that of other surface-treated implants.

Use of particulate dentin-plaster of Paris combination with/without platelet-rich plasma in the treatment of bone defects around implants.

PURPOSE: To evaluate the effect of particulate dentin-plaster of Paris with and without platelet-rich plasma (PRP) on bone healing and new bone formation around titanium dental implants in a canine model. Histologic sections and histomorphometric analysis of the defects were obtained at 6 and 12 weeks after surgery. MATERIALS AND METHODS: Three circular bone defects were surgically prepared in iliac crest sites in each of 10 animals. A total of 30 Avana dental implants were placed in the animals. They were self-tapping, screw-type implants, 10 mm in length and 4 mm in diameter, all made of commercially pure titanium. A titanium implant was placed centrally in each defect. In each dog, the defects were treated with 1 of the following 3 treatment modalities: (1) no treatment (control); (2) grafting with particulate dentin-plaster of Paris; (3) grafting with particulate dentin-plaster of Paris and PRP. RESULTS: Histologic analysis showed that all of the bone defects surrounding the implants that were treated with particulate dentin-plaster of Paris, with and without PRP, were filled with new bone. The defects that were not treated (control) demonstrated new bone formation only in the inferior threaded portion of the implants. DISCUSSION: Histomorphometric results revealed a higher percentage of bone contact with particulate dentin-plaster of Paris and PRP compared to the control and particulate dentin-plaster of Paris. CONCLUSIONS: These results suggested that bone defects around titanium implants can be treated successfully with particulate dentin-plaster of Paris, and that the outcome can be improved if PRP is also used.

Familial tooth bone graft for ridge and sinus augmentation: a report of two cases.

Recently, clinical application of autogenous tooth bone-graft materials has been reported. Autogenous tooth bone graft has been used in implant surgery. Familial tooth bone graft is a more advanced procedure than autogenous teeth bone graft in that extracted teeth can be used for bone graft materials of implant and teeth donation between siblings is possible. We used autogenous tooth and familial tooth bone-graft materials for ridge augmentation and sinus bone graft and obtained satisfactory results. The cases are presented herein.

A comparative study of bone formation following grafting with different ratios of particle dentin and tricalcium phosphate combinations.

This study aimed to evaluate the bone regeneration relative to tooth powder and tricalcium phosphate (TCP) mixing ratios using the rabbit cranium defect model. The tooth powder was mixed with TCP in 1:1, 3:1, and 1:3 ratios, and the different ratios were implanted in the rabbit cranium defect for 4 and 8 weeks. Powders crystal structure evaluated using scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and new bone formation (NBF) was analyzed using micro-computed tomography (CT) and histologic examination. NBF in the control group was restricted to the defect margins. More NBF was observed around the defect margins in the experimental groups compared with the control group. Specifically, active NBF was identified around the implant materials of the centrifugal part of the defect and defect margins in the 3:1 tooth powder: TCP group. Our results suggested that tooth powder and TCP may be useful in bone regeneration.

Effect of platelet-rich plasma and platelet-rich fibrin on peri-implant bone defects in dogs.

The purpose of this study was to evaluate the effect of tooth ash and platelet-rich plasma (PRP), and platelet-rich fibrin (PRF) grafts into bone defects around implants on bone formation. Six adult dogs were used as experimental subjects. Graft materials were used to create a particulate material. Forty-eight tapered-type implants, 3.7 mm in diameter, 10 mm in length, and with surface treated with hydroxyapatite (HA) coating, were used as implant fixtures. Using a trephine bur, four bone defects were formed and implants were placed in the femurs of the adult dogs. Bone grafts were not performed in the control group. Tooth ash was grafted into the defects in group 1. In group 2, a mixture of tooth ash and PRP (1:1 ratio by volume) was grafted into the defects. In group 3, a mixture of tooth ash and PRF (ratio of 1:1) was grafted in the defect area. Animals were sacrificed after 4 or 8 weeks. Based on histopathological examination, the amount and rate of new bone formation were evaluated. Histomorphometric examination revealed that the rate of new bone formation in group 3 of the 4-week group was significantly higher than that in the control group. In addition, in the 8-week group, a significant increase in new bone formation was confirmed in group 3. In this study, a bone graft method using a mixture of tooth ash and PRF was found to increase new bone formation compared to the method using PRP. In addition, it was confirmed that this effect was more prominent in the initial stage of the bone graft.

Effect of guided bone regeneration with or without pericardium bioabsorbable membrane on bone formation.

OBJECTIVE: The purpose of this study was to evaluate bone formation after using allogeneic bone alone or with a membrane. STUDY DESIGN: Bone graft was performed using the allograft Tutoplast, mineralized cancellous bone allograft, and pericardium in calvarial defects of 60 rats. Rats were divided in 3 groups: control group (no bone graft), group 1 (bone graft without membrane), and group 2 (bone graft with membrane). RESULTS: The most new bone formation occurred in group 2. After 6 weeks, group 2 showed infiltration of inflammatory cells, and inflammatory cells were still observed after 12 weeks. The membrane remained even after 12 weeks, and the membrane facilitated bone regeneration by blocking connective tissue. CONCLUSIONS: The membrane facilitated new bone formation by inhibiting connective tissue invasion.

Influence of unilateral tooth loss in the temporomandibular joint and masseter muscle of rabbits.

OBJECTIVE: The purpose of this study was to evaluate the influence of the masticatory system in patients with missing teeth. STUDY DESIGN: The influence of tooth loss on the masticatory system was analyzed with the use of bone scintigraphy ((99m)Tc-MDP) and histochemistry. Eight white rabbits (New Zealand, 12 weeks old) were used. The rabbits were divided into 2 groups: 6 weeks and 12 weeks. Teeth were extracted unilaterally in each rabbit under general anesthesia. Six and 12 weeks after extraction, scintigraphy was conducted, and the rabbits were killed and their masseter muscles removed for histochemical analysis. RESULTS: The results of bone metabolism (relative ratio) measured by bone scintigraphy were 48.27% at extraction sites and 51.73% at nonextraction sites at 6 weeks and 39.96% at extraction sites and 60.04% at nonextraction sites at 12 weeks. There was a significant difference at 12 weeks (P < .05). Tissue calcium contents and osteoclast counts showed different results between the extraction and nonextraction sites, but these differences did not reach statistical significance. CONCLUSIONS: The bone metabolism of temporomandibular joints and histochemical aspects of masticatory muscles may be associated with occlusal alterations following tooth loss.

Effect of Tisseel on bone healing with particulate dentin and plaster of Paris mixture.

OBJECTIVES: The purpose of this study was to evaluate the effect of Tisseel on the early healing of bone defects in the skulls of rats. STUDY DESIGN: Forty-eight rats were randomly assigned to 4 groups, and each group was further divided into 3 subgroups which were examined at 4 and 8 weeks after the defects were filled. The 4 different groups were animals containing: no graft (group 1); particulate dentin and plaster of Paris mixture graft (group 2); Tisseel and particulate dentin and plaster of Paris mixture graft (group 3); and Tisseel graft (group 4). After killing the animals at 4 and 8 weeks after surgery, all implant blocks were prepared for histologic sections and histomorphometric analysis. RESULTS: The overall new bone formation was significantly different between the 4-week samples and the 8-week samples. Significant differences between groups 1 and 2, groups 1 and 3, groups 1 and 4, groups 2 and 4, and groups 3 and 4 were observed at 4 weeks after surgery. At 8 weeks after surgery, significant differences between groups 1 and 2, groups 1 and 3, groups 1 and 4, and groups 2 and 4 were observed. As expected, effective bone formation was observed when the defects were filled with either particulate dentin, Tisseel, or particulate dentin-Tisseel combination. It was also observed from this study that particulate dentin is especially effective, followed by the particulate dentin-Tisseel combination and Tisseel. CONCLUSION: It was concluded that the use of Tisseel may be an alternative therapy for regenerating bone in defects when used in combination with particulate dentin.