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.

Incidence and Management of Fractured Dental Implants: Case Reports.

The fracture of dental implants is a rare occurrence in clinical settings. Possible causes of implant fracture include design or production flaws, overloaded occlusion force, implant location, metal fatigue, and bone resorption around the implant. This study reports on the successful removal and reimplantation of fractured implants.

Sinus Membrane Elevation by the Crestal Approach Using a Novel Drilling System.

PURPOSE: The purpose of this study was to evaluate the clinical outcomes of patients undergoing sinus membrane elevation by a minimally invasive crestal approach using a novel drilling system. MATERIALS AND METHODS: From May 2008 to November 2009, 21 implants were placed in 19 patients (10 men and 9 women) ranging from 23 to 69 years of age (average of 49.5 years). Implants were placed in maxillary premolar and molar areas that demonstrated insufficient residual bone quality; maxillary sinus membrane elevation was performed using a crestal approach with the sinus crestal approach kit (Neobiotech, Seoul, Korea). RESULTS: There was no sinus perforation or osseointegration failure. The implant survival rate was 100%. The postsurgical, augmented volume of the alveolar height ranged from 2 to 9.2 mm (average of 5.81 ± 2.06 mm). Six months after maxillary sinus elevation, the bone reduction volume ranged from 0.06 to 1.42 mm (average of 0.6 ± 0.38 mm). At final F/U, the amount of bone-height reduction ranged from 0.06 to 2.60 mm (average of 0.82 ± 0.63 mm). CONCLUSION: Sinus membrane elevation by the crestal approach using special reamers is advantageous because of the noticeable reduction in the risk of perforation and the ability to perform the surgery rapidly.

Synthesis and Characterization of ß-Tricalcium Phosphate Derived From Haliotis sp. Shells.

PURPOSE: To develop a methodology for the synthesis of ß-tricalcium phosphate (ß-TCP, Ca3(PO4)2) from the shell of Haliotis sp. (abalone shell) and to verify its characterization and biocompatibility. MATERIALS AND METHODS: Calcium oxide (CaO) was synthesized from abalone shell by sintering and was suspended in distilled water to prepare calcium hydroxide (Ca(OH)2). For the synthesis of calcium carbonate (CaCO3), carbon dioxide was used to infuse Ca(OH)2 at pH 7.4. CaCO3 was reacted with phosphoric acid at pH 6.0 to obtain dicalcium phosphate (CaHPO4). Subsequently, ß-TCP was synthesized by a chemical reaction between CaHPO4 and CaO at 950°C to 1100°C for 3 hours. Fourier transform infrared spectroscopy (FT-IR) and x-ray diffraction (XRD) was performed to verify the physiochemical characteristics of the composite synthesized from abalone shell. RESULTS: FT-IR and XRD results showed that ß-TCP was successfully synthesized from abalone shell. The synthesized ß-TCP did not affect cell viability of either normal human oral keratinocytes or osteoblastic MG-63 cells. These data indicate that ß-TCP synthesized from abalone shell is biologically safe. CONCLUSIONS: ß-TCP (Ca3(PO4)2) synthesized from abalone shell can be used as a potential source of bone grafting material.

A Retrospective Analysis of the Retreatment of Failed Sinus Bone Grafts.

This analysis examined the types of retreatment in failed sinus bone grafts due to the development of maxillary sinusitis. Reoperation was performed in 7 patients. The types of reoperation included infection management, reconstruction of the sinus roof using a pedicled buccal fat pad and collagen membrane, oroantral fistula closure, sinus bone graft using an autogenous bone graft, and implant placement. In one case, sinusitis developed 14 months after the reoperation, but it was managed by incision, drainage, and administration of antibiotics. All sinus bone grafts that were performed during the retreatments were successful.

Implants Displaced Into the Maxillary Sinus: A Systematic Review.

OBJECTIVES: Implant displacement into the maxillary sinus often results from features specific to the posterior maxillary teeth, including poor bone quality and insufficient remaining bone. This study reviews implants displaced into the maxillary sinus, the causes and complications of displacement, and how to remove them, according to when the displacement occurs. MATERIALS AND METHODS: The PubMed, Ovid (MEDLINE), and EMBASE databases were searched using the keywords "displacement," "implant," "maxillary sinus," and "removal" for articles published between January 2000 and July 2013. RESULTS: Twenty-two journal articles were selected; these discussed 49 displaced implants. Most of the implants were displaced into the maxillary sinus during implantation, but resulted in a low incidence of complications, such as maxillary sinusitis. The displaced implants were removed using the Caldwell-Luc approach or a transoral or transnasal endoscopic approach. CONCLUSION: Implants displaced into the maxillary sinus have various causes according to when they are displaced. As displaced implants can cause several complications, transnasal endoscopy is recommended to remove them; however, the implants should be examined thoroughly before selecting the removal method.

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.

Implant Stability Measurements in the Long-Term Follow-up of Dentis Implants: A Retrospective Study With Periotest.

PURPOSE: The purpose of this study was to evaluate retrospectively the stability of Dentis implant with the Periotest. METHODS: In total, 36 patients and 88 implants were investigated. Periotest was used to measure implant stability, and a periapical view was taken immediately after surgery and again immediately after, 3 months after, 6 months and 5 years after prosthesis placement. Bone loss on the periapical view, bone quality according to tactile sensation, and area of implant installation were assessed. RESULTS: The mean Periotest value (PTV) immediately after surgery was -1.02, and the mean bone loss rate (bone loss/fixture length × 100) at 6 months after prosthesis placement was 8.42%. PTV was higher with more bone loss (types III, IV vs types I, II bone). The lowest mean PTV was in the lower molar area (-1.48), followed by the lower anterior (-1.41), upper molar (0.11), and upper anterior area (5). One implant failed and survival rates were 98.9%. CONCLUSION: Implant stability was lower in cases with more bone loss and poor bone quality and in the maxilla versus the mandible.

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.

Downregulation of adenomatous polyposis coli by microRNA-663 promotes odontogenic differentiation through activation of Wnt/beta-catenin signaling.

MicroRNAs (miRNAs) regulate cell differentiation by inhibiting mRNA translation or by inducing its degradation. However, the role of miRNAs in odontogenic differentiation is largely unknown. In this present study, we observed that the expression of miR-663 increased significantly during differentiation of MDPC-23 cells to odontoblasts. Furthermore, up-regulation of miR-663 expression promoted odontogenic differentiation and accelerated mineralization without proliferation in MDPC-23 cells. In addition, target gene prediction for miR-663 revealed that the mRNA of the adenomatous polyposis coli (APC) gene, which is associated with the Wnt/ß-catenin signaling pathway, has a miR-663 binding site in its 3'-untranslated region (3'UTR). Furthermore, APC expressional was suppressed significantly by miR-663, and this down-regulation of APC expression triggered activation of Wnt/ß-catenin signaling through accumulation of ß-catenin in the nucleus. Taken together, these findings suggest that miR-663 promotes differentiation of MDPC-23 cells to odontoblasts by targeting APC-mediated activation of Wnt/ß-catenin signaling. Therefore, miR-663 can be considered a critical regulator of odontoblast differentiation and can be utilized for developing miRNA-based therapeutic agents.

Displaced implants into maxillary sinus: report of cases.

Although the number of implant placement in the edentulous maxillary region is increasing, there are often some cases in which implants accidentally get displaced into maxillary sinus because of low bone quality, insufficient bone height, bone resorption after surgery, and improper treatment plan. Implants displaced into the maxillary sinus can cause some complications, including mucosal thickening and sinusitis; however, there are also many cases causing no symptoms at all. Treatment procedures for implants displaced into maxillary sinus are observation, removal of implants through intraoral approach, and removal through nasal cavity using endoscope. But treatment may vary according to the presence of sinusitis, ostium obstruction, and oroantral fistula. In this study, 4 patients with present illness of implants displaced into maxillary sinus were selected, and appropriate evaluation and treatment for these cases were studied.

Reliability of 2 implant stability measuring methods in assessment of various periimplant bone loss: an in vitro study with the Periotest and Osstell Mentor.

PURPOSE: The aim of this in vitro study was to evaluate reliability of the Periotest and Osstell Mentor in assessment of periimplant vertical and circular bone loss. MATERIALS AND METHODS: Sixteen dental implants were embedded into acrylic resin blocks. The portion of resin around the implant neck was successively removed to mimic periimplant vertical and circular bone loss. Measurement values of 2 devices were compared by assessing the change of Periotest value (PTV) and Implant Stability Quotient (ISQ) values, by calculating correlation analysis and by means of regression analysis referring to increasing bone loss. RESULTS: Both devices were able to discriminate differences of circular bone loss. However, PTVs were not noticeably changed in buccal, buccal-mesial, and buccal-mesial-distal bone loss. The differences in buccal and buccal-mesial bone loss were not discriminated by Osstell Mentor. As the range of bone loss was increased, there was a noticeable correlation of the PTV and ISQ values. CONCLUSIONS: The results of this study suggest that both diagnostic devices for implant stability are useful in detecting the circular bone loss. However, the clinical reliability of both devices for detecting the partial vertical bone loss is low.

Guided bone regeneration using autogenous tooth bone graft in implant therapy: case series.

Recently, techniques have been reported that involve the preparation of extracted teeth from patients used as particulated bone graft materials for bone graft purposes. For implant placement and bone graft, autogenous teeth bone graft materials were used in 15 patients, and clinically excellent results were obtained. In histological examination, favorable bony healing by osteoconduction was observed.

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.

Enhanced attachment of human osteoblasts on NH3-treated poly(L-lactic acid) membranes for guided bone regeneration.

Barrier membranes for guided bone regeneration (GBR) were prepared by a solvent casting method using solutions of poly(L-lactic acid) (PLLA) and chitosan. PLLA and PLLA/chitosan membranes were treated with ammonia gas plasma. PLLA/chitosan membranes were successfully fabricated, and the surface of the PLLA/chitosan membrane was clearly modified by NH3 plasma treatment according to attenuated total reflectance (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analyses. Additionally, water contact angle testing indicated that the hydrophilicity of these membranes was significantly increased. MG-63 cells were cultured on each type of membrane, and cell viability was examined using an MTT assay. After one week of culturing, MG-63 cells were more abundant on PLLA/chitosan membranes than on PLLA membranes. The cell viability of PLLA/chitosan membranes with plasma treatment was significantly higher than that of PLLA membranes. These results suggest that this plasma-treated membrane is suitable for GBR and is a promising source of bioactive membrane material for bone regeneration.

Bone graft using block allograft as a treatment of failed implant sites: clinical case reports.

Alveolar bone should be augmented to an adequate height and width for an implant to have satisfactory functional, biological, and aesthetic properties. Large osseous defects often require block grafts harvested from the symphysis or ramus. However, surgical complications and the necessity of donor sites have led to using allogeneic grafting materials. Two patients with severe bone defects on their mandibular posterior and maxillary posterior teeth were selected to be the subjects of this study. These 2 patients needed their implant fixtures removed due to implant failure. They received alveolar ridge augmentation using commercial block allografts, and after an integration period of several months, an implant was placed. The short-term results suggest that block allografts may be suitable bone-replacement materials for augmenting alveolar defects, especially for bone grafts in bone defect areas caused by removing failed implants.

Consideration of various bone quality evaluation methods.

PURPOSE: Bone quality at the implant site has a significant effect on the success and prognosis of implants. The purpose of this article was to evaluate several methods used in evaluating bone quality and discuss the advantages and disadvantages. METHODS: The search was made using PubMed database about quantitative computed tomography (QCT), and quantitative cone-beam computerized tomography (QCBCT), dual energy x-ray absorptiometry (DXA) scans, the resistance force against the hands of the surgeon, assessment of the effect of the torque of the drill, the initial fixed value of the implant, and fractal analysis according to the Lekholm and Zarb, and Misch classifications as the standard. RESULTS: The method for measuring the resistance force and torque during implant placement and the method used to determine the implant's initial implant fixed value were easy and simple. QCBCT was reported to involve less radiation and to be more objective than QCT. DXA and fractal analysis have limits when used to classify bone quality as type II or type III. CONCLUSION: Among the methods used to evaluate bone quality in implants, a method using computed tomography, measured in Hounsfield units, was found to be the most predictive.

Bone grafts using autogenous tooth blocks: a case series.

OBJECTIVE: A case study was conducted to examine the clinical results and histologic healing of bone grafts performed using an autogenous tooth block (AutoBT block), which was developed recently and proprietary. STUDY DESIGN: Guided bone regeneration, extraction socket graft, sinus bone graft, and ridge augmentation were performed using autogenous tooth block graft material in 12 patients from March 2009 to June 2010. The clinical outcomes of each case were examined, and tissue specimens were collected from 1 case 2.5 months after the bone graft for histopathological analysis. RESULTS: All of the cases had successful bone graft results. One patient developed wound dehiscence after surgery, although favorable secondary healing was achieved. One implant resulted in osseointegration failure. A histopathologic examination was performed after 2.5 months and showed excellent bone healing due to osteoconduction. The AutoBT block was incorporated into the upper soft tissue, aponeurosis, and lower recipient bone. CONCLUSION: There were no notable complications associated with the bone transplant materials. The AutoBT block is clinically useful for a variety of bone grafts.