Influences of Schneiderian membrane conditions on the early outcomes of osteotome sinus floor elevation technique: a prospective cohort study in the healing period.

OBJECTIVES: To radiographically investigate early outcomes of osteotome sinus floor elevation in the healing phase utilizing cone beam computed tomography and evaluate influences of Schneiderian membrane conditions. MATERIAL AND METHODS: One hundred patients were consecutively recruited for osteotome sinus floor elevation (OSFE) surgery using deproteinized bone mineral. CBCT was taken prior to (T0), immediately post-operatively (T1), and after the healing period (T2). Linear and volumetric measurements of the elevated region from T0 to T1 were performed for evaluation on computed tomography (CT). RESULTS: Osteotome sinus floor elevation were performed in 100 patients. One implant of each patient was selected. Mean residual bone height (RH) was 7.21 ± 1.12 mm. Mean sinus floor elevation height (SE) was 4.81 ± 0.75 mm. The mean endo-sinus bone gain after the healing period was 3.25 ± 0.83 mm. Pre-opterative CBCT scans revealed that 72 patients had a normal sinus membrane in osteotome region, 13 patients presented with flat thickened mucosa and 15 patients with antral pseudocysts. There is no significant difference in sinus mucosa elevation height, bone graft volume and new bone formation in group of Thickening membrane and Antral pseudocysts compared with normal. CONCLUSIONS: The radiographical results show that OSFE is a safe and predictable surgical procedure in residual bone height of 7.21 ± 1.12 mm. Mild flat thickening (>2 and <5 mm) and antral pseudocysts in a small size without clinical symptoms may not be contraindications to OSFE surgery.

Subtrochanteric shortening osteotomy during cementless total hip arthroplasty in young patients with severe developmental dysplasia of the hip.

BACKGROUND: This retrospective study was designed to determine complications, functional and radiographic results of transverse subtrochanteric osteotomy during cementless, modular total hip arthroplasty (THA) in a series of active patients younger than 45 years with Crowe Type-III or IV developmental dysplasia of the hip (DDH). METHODS: We followed 49 patients (56 hips) with DDH who were treated with cementless THA, where the acetabular cup was positioned in the anatomic hip center and where a simultaneous transverse femoral osteotomy was performed. Complication rate evaluation and clinical outcomes were measured by validated clinical scores and radiographic evaluation were performed at a mean follow up of 10 years (range, 4.8-14.3 years). RESULTS: The mean limb-length discrepancy was reduced from 4.2 cm to 1.1 cm (P < 0.01). The mean Harris hip score (HSS) significantly improved from 40.6 points to 87.4 points (P < 0.01). Similarly, severity of low back pain, modified MAP, HOOS, and SF-12 also showed significant improvement (P < 0.01). There were 3 cases of postoperative dislocation, 3 cases of transient nerve palsy, 2 cases of nonunion, and 4 cases of intraoperative fracture. At 10 years follow-up, the estimated survival rate with any component revision as end points was 92%. CONCLUSION: The cementless THA combined with transverse subtrochanteric osteotomy is a reliable technique with restoration of a more normal limb, satisfactory clinical outcomes, and mid-term survival of components.

Longitudinal response of membrane thickness and ostium patency following sinus floor elevation: a prospective cohort study.

OBJECTIVES: To investigate the influence of sinus floor elevation (SFE) on sinus physiology, including Schneiderian membrane thickness (MT) and ostium patency, using cone beam computed tomography (CBCT). MATERIALS AND METHODS: Based on pre-established selection criteria, 53 patients in combination with 53 sinuses were referred for SFE with a lateral approach using deproteinized bone mineral. CBCT was performed prior to, immediately after surgery and before staged implant placement. The Schneiderian MT of the elevated region, ostium patency, and other clinical data was evaluated. RESULTS: The two-stage sinus augmentation technique was applied in 33 males and 20 females. Four membrane perforations were observed during the surgical procedure. The Schneiderian membrane exhibited significant swelling immediately after augmentation (P < 0.0001), but this difference disappeared after a mean healing period of 7.51 months. The corresponding changes were also observed for ostium patency with a tendency of transient obstruction after surgery. Sinuses with flat mucosal thickening or pseudocysts did not present a liability of perforation compared to the normal cases, and the augmentation procedure was not likely to deteriorate the pathology of mucosal thickening or pseudocysts. CONCLUSIONS: The results show that SFE with a lateral approach has no significant influence on MT and ostium patency after the healing period except for postoperative transient swelling and obstruction. Thickened membranes and antral pseudocysts in a small size might not be contraindications to SFE from the standpoint of the surgical impact on the Schneiderian membrane.

Torsional resonance frequency analysis: a novel method for assessment of dental implant stability.

OBJECTIVES: To establish and experimentally validate a novel resonance frequency analysis (RFA) method for measurement of dental implant stability by analyzing torsional resonance frequency (TRF). MATERIAL AND METHODS: A numerical study and in vitro measurements were performed to evaluate the feasibility and reliability of the method of torsional RFA (T-RFA) using a T-shaped bilateral cantilever beam transducer. The sensitivity of this method was assessed by measuring the TRFs of dental implants with 8 sizes of T-shaped transducers during polymerization, which simulated the process of bone healing around an implant. The TRFs of the test implants detected using this new method and the bending resonance frequencies (BRFs) measured by Osstell(®) ISQ were compared. TRFs and BRFs on implant models in polymethyl methacrylate (PMMA) blocks with three exposure heights were also measured to assess the specificity of this method. RESULTS: Finite element analysis showed two bending modes (5333 and 6008 Hz) following a torsional mode (8992 Hz) in the lower rank frequency. During in vitro measurements, a bending formant (mean 6075 Hz) and a torsional formant (mean 10225 Hz) appeared, which were verified by multipoint measurement with invariable excitation frequency in the laboratory. In the self-curing resin experiments, the average growth rate at all time points of TRFs using the new method with Transducer II was 2.36% and that of BRFs using Osstell(®) ISQ was 1.97%. In the implant exposure height tests, the mean declined rate of TRFs was 2.06% and that of BRFs using Osstell(®) ISQ was 12.34%. CONCLUSION: A novel method for assessment of implant stability through TRF was established using a T-shape transducer, which showed high reliability and sensibility. The method alleviated the effects of implant exposure height on the measurements compared with Osstell(®) ISQ. The application of T-RFA represents another way in the investigation of dental implant osseointegration.

Ridge expansion alone or in combination with guided bone regeneration to facilitate implant placement in narrow alveolar ridges: a retrospective study.

OBJECTIVE: To evaluate the long-term outcomes of ridge expansion technique in dealing with horizontal bony insufficiency of alveolar ridges for implant placement. MATERIALS AND METHODS: During the period 2004-2009, 168 patients with width insufficiency of alveolar ridges were treated using the ridge expansion technique to obtain an improved bony base for implant placement. Depending on the severity of width insufficiency, the surgical procedures were classified into two groups: ridge expansion alone (Group 1) and ridge expansion in combination with guided bone regeneration (Group 2). After 4-6 months of unloaded healing, the implants were restored. The patients were followed up until 2013 with clinical and radiographic examinations. RESULTS: Among the 168 patients, 11 patients underwent a fracture of labial/buccal bony plate during surgery, which was corrected by changing the procedure into bone grafting, yielding a surgical failure rate of 6.5%. In the remaining 157 patients successfully treated by ridge expansion alone or in combination with GBR, 226 implants were simultaneously placed as planned. No implant failed over 2.8 years (6 months to 8 years) of follow-up, yielding a cumulative implant survival rate of 100% in each group. Six implants in Group 1 and 4 implants in Group 2, although osseointegrated and in function, did not fulfill success criteria: Cumulative implants' success rates were 93.2% in Group 1 and 95.6% in Group 2. The mean marginal bone losses during the first year in Group 1 and Group 2 were 0.69 and 0.43 mm, respectively, followed by an annual loss of ~ 0.06 and 0.07 mm, respectively, in the following years. No clinical parameter was abnormal. Twenty-two (10.4%) implants were exposed to peri-implant mucositis, whereas 19 (11.0%) implant-supported restorations were involved in prosthetic complications. CONCLUSIONS: The preliminary results of this retrospective study indicate that ridge expansion alone or in combination with GBR can be considered an effective and safe procedure for treatment of width insufficiency of alveolar ridges on the purpose of implant application.

Evaluation of fixation of expandable implants in the mandibles of ovariectomized sheep.

PURPOSE: This study aimed to investigate the effects of an expandable implant (EI) in ovariectomized sheep. METHODS: The EI and taper implant (control group) were produced and placed in mandibles of ovariectomized sheep. Twelve weeks after implantation, resonance frequency analysis, biomechanical tests, histomorphometry, and micro-computed tomography were applied to detect the osseointegration in the 2 groups. RESULTS: The implant stability quotient values, maximal pullout forces, and bone-implant contact (BIC) were 60.3 ± 7.9, 511.0 ± 18.7 N, and 53.14% ± 4.56%, respectively, in the EI group and 58.3 ± 8.9, 394.5 ± 54.5 N, and 46.85% ± 5.04%, respectively, in the control group. There was no significant difference between the 2 groups in implant stability quotient values (P > .05); however, in the EI group the maximal pullout force and BIC were increased significantly (P < .05 and P < .01, respectively). Micro-computed tomography analysis showed that the bone volume/total volume ratio and trabecular number increased significantly (P < .01) and trabecular separation decreased significantly (P < .05) in the EI group. CONCLUSIONS: EI could improve osseointegration in osteoporosis after 12 weeks of implantation by increasing BIC around the implant and by supplying an extra osseointegration surface.

A novel technique for implant-supported fixed complete rehabilitation based on a dynamic virtual patient.

BACKGROUND: A digital workflow for implant-supported fixed complete prostheses (ISFCP) using photogrammetry (PG), virtual articulator (VA), and virtual facebow (VF) data remains a challenge. METHODS: The novel ISFCP technique included four steps: (1) formation of a dynamic virtual patient, (2) integration of PG data, (3) fabrication of a diagnostic ISFCP, and (4) fabrication of a definitive ISFCP and test of the deviation. RESULTS: Dynamic virtual patients were formed by integrating PG, VA, and VF data. The cumulative root mean square deviation between the designed data and actual definitive prosthesis was 140.4 µm. CONCLUSIONS: The novel technique for ISFCP fabrication described in this paper can help optimise the clinical efficiency and quality of ISFCP but requires an initial learning curve. CLINICAL SIGNIFICANCE: This technique provides a direct workflow, using PG, VA, and VF data, to fabricate ISFCP based on the provisional restoration.

[Maxillary sinus floor augmentation with Bio-Oss as a sole graft: a histologic, radiographic and preliminary clinical study].

OBJECTIVE: To evaluate new bone formation and preliminary clinical outcomes following maxillary sinus floor augmentation with Bio-Oss alone. METHODS: Nine patients were treated with ten maxillary sinus floor augmentations using Bio-Oss alone, and eighteen Straumann implants were placed. After five to eleven-month healing period at implant placement, cylindrical specimens were biopsied from the augmented area. The new bone formation of specimens was analyzed by histology and micro-computed tomography. Cone beam computed tomography (CBCT) scans were performed for measurements of residual crestal bone height under the sinus, the amount of increased height immediate after the augmentation and before implant insertion. To monitor stability changes, resonance frequency analysis was performed and implant stability quotient (ISQ) values were collected at implant placements (baseline,0 month), one month, three months and six months after placements. RESULTS: All implants were loaded six months after insertion and no failures were recorded. Compared to adjacent native bone, no significant differences of bone volume fraction were found in augmented area (P > 0.05), together with lower trabecular number (P < 0.05) and trabecular thickness (P < 0.01) as well as higher trabecular separation (P < 0.01) by microradiographic analysis.Histomorphometrically, there was no significant difference in the amount of new bone formation between the adjacent native bone and augmented area (P > 0.05). CBCT showed a bone height gain of (14.19 ± 2.02) mm immediate after augmentation, which stabilized at (13.68 ± 1.95) mm after bone healing period. Mean ISQ value was 71.94 ± 6.51 at baseline, decreased to 70.19 ± 6.38 at 1 month, and increased to 78.17 ± 3.83 at 3 month and 82.56 ± 3.20 at 6 month. CONCLUSIONS: The use of Bio-Oss as the sole graft is reliable and can lead to satisfactory bone formation and clinical outcome.

A new submerged split-thickness skin graft technique to rebuild peri-implant keratinized soft tissue in composite flap reconstructed mandible or maxilla.

OBJECTIVE: The objective of this study was to introduce our preliminary experience on a submerged split-thickness skin graft (STSG) technique combined with secondary vestibuloplasty to rebuild keratinized peri-implant soft tissue and oral vestibule for patients with large oromandibular defects reconstructed by composite flaps. PATIENTS AND METHODS: Five patients were enrolled in this study. Stage 1 was submerged STSG and simultaneous implant placement. Stage 2 was the uncovering of the STSG and vestibuloplasty. The implant-borne fixed denture was inserted after this 2-stage treatment. All patients were followed for at least 12 months (average 18 months). RESULT: Eighteen implants were placed. The rebuilt peri-implant keratinized soft tissue was healthy clinically. The STSG graft had firm adherence to the underlying periosteum. The vestibule had adequate depth to maintain local hygiene. All implants were osseointegrated and all implant-borne prostheses were functioning well. CONCLUSION: Submerged STSG technique combined with secondary vestibuloplasty may become a feasible and effective solution to rebuild keratinized soft tissue before dental implant restoration.

Effects of local delivery of bFGF from PLGA microspheres on osseointegration around implants in diabetic rats.

OBJECTIVE: Diabetes mellitus may impair bone healing after dental implant placement. The objective of this study was to evaluate the effects of the local delivery of basic fibroblast growth factor (bFGF) from poly(lactide-co-glycolide) (PLGA) microspheres on osseointegration around titanium implants in diabetic rats. STUDY DESIGN: The bFGF-PLGA microspheres were prepared by the W/O/W double-emulsion solvent evaporation method. A total of 20 rats were used to create diabetic animal models by giving them a high-fat and high-sugar diet and a low-dose streptozotocin intraperitoneal injection. Titanium implants were planted into the tibias of the diabetic rats and into 10 normal rats. Microspheres were loaded on the surfaces of the implants in the bFGF intervention group before they were placed into the rats. After 4 or 8 weeks, the tibias containing the implants were removed and embedded with resin. Uncalcified tissue slices were prepared to compare osseointegration. RESULTS: At 4 weeks, the bone-implant contact rate in the diabetic control group was less than that in the control group and the bFGF intervention group (P < .05). At 8 weeks, the results among the 3 groups were similar to those at 4 weeks. CONCLUSIONS: The local delivery of bFGF from PLGA microspheres into areas around titanium implants may improve osseointegration in diabetic rats.

In vitro culture and characterization of alveolar bone osteoblasts isolated from type 2 diabetics.

In order to understand the mechanisms of poor osseointegration following dental implants in type 2 diabetics, it is important to study the biological properties of alveolar bone osteoblasts isolated from these patients. We collected alveolar bone chips under aseptic conditions and cultured them in vitro using the tissue explants adherent method. The biological properties of these cells were characterized using the following methods: alkaline phosphatase (ALP) chemical staining for cell viability, Alizarin red staining for osteogenic characteristics, MTT test for cell proliferation, enzyme dynamics for ALP contents, radio-immunoassay for bone gla protein (BGP) concentration, and ELISA for the concentration of type I collagen (COL-I) in the supernatant. Furthermore, we detected the adhesion ability of two types of cells from titanium slices using non-specific immunofluorescence staining and cell count. The two cell forms showed no significant difference in morphology under the same culture conditions. However, the alveolar bone osteoblasts received from type 2 diabetic patients had slower growth, lower cell activity and calcium nodule formation than the normal ones. The concentration of ALP, BGP and COL-I was lower in the supernatant of alveolar bone osteoblasts received from type 2 diabetic patients than in that received from normal subjects (P < 0.05). The alveolar bone osteoblasts obtained from type 2 diabetic patients can be successfully cultured in vitro with the same morphology and biological characteristics as those from normal patients, but with slower growth and lower concentration of specific secretion and lower combining ability with titanium than normal ones.

Type 2 diabetes mellitus impairs bone healing of dental implants in GK rats.

Type 2 diabetes is an increasingly prevalent disease with oral health manifestations. In this study, titanium implants were placed in the femora of 10 type 2 diabetic and 10 age-matched normal rats. We compared the results of bone histomorphometry around the dental implants at 4 and 8 weeks postsurgery.

Sustained release of insulin-like growth factor-1 from poly(lactide-co-glycolide) microspheres improves osseointegration of dental implants in type 2 diabetic rats.

Dental implantation is an effective and predictable treatment modality for replacing missing teeth and repairing maxillofacial defects. However, implants in patients with type 2 diabetes mellitus are likely to have a high failure rate and poor initial osseointegration. In the current study, we established an effective drug delivery system designed to improve osseointegration of dental implants in an animal model of type 2 diabetes. Twenty type 2 diabetic rats were divided into two groups: a group receiving recombinant rat Insulin-like Growth Factor 1 (rrIGF-1) Microsphere Therapy (MST) (10 rats) and a control group (10 rats). The rrIGF-1 was encapsulated into poly(lactide-co-glycolide) (PLGA) microspheres to produce a sustained-release effect around titanium (Ti) dental implants in the rrIGF-1 MST group. Scanning electron microscopy, confocal laser scanning microscopy, and cumulative-release studies were conducted to verify the release effect of the microspheres as well as rrIGF-1 bioactivity. Five rats from each group were sacrificed at weeks 4 and 8 post surgery, and a histological analysis was performed on the rats from both groups. Compared to the control group, rats that received rrIGF-1 by PLGA microsphere treatment were observed to have a higher bone-implant contact percentage around the Ti implants at week 4 or week 8 post surgery (P<0.05). This result clearly indicates that sustained release of rrIGF-1 through encapsulation by PLGA microspheres positively affects osseointegration of dental implants in type 2 diabetic rats.

Histological evaluation and surface componential analysis of modified micro-arc oxidation-treated titanium implants.

The objective of this study is to investigate soft tissue and bone tissue reaction to titanium implants treated by a modified micro arc oxidation (MAO) technique, and analyze the surface components and implant-bone contact ratio by animal experiments to evaluate the osseointegration condition of implants with this modified MAO surface. MAO titanium plates were installed subcutaneously in rabbits. Tissue reaction was evaluated by HE sections. MAO titanium implants designed for endosseous examination were installed in Beagles' femurs. Bone tissue surrounding implants was analyzed histologically. Surfaces of retrieved implants were observed and examined by SEM and EDX. All procedures were performed under the control of untreated pure titanium implants. Thin homogeneous fibrous envelope could be found without apparent inflammation cells infiltration around the subcutaneously imbedded MAO titanium plates, which was almost same as control group. Fast osteoid deposition comprising high content of calcium, phosphor, carbon, and nitrogen elements was found on the retrieved MAO implant surfaces, while comparatively less amount of carbon and nitrogen elements were found on the retrieved implants of control group. Matured bone tissue comprising bone trabeculae and Haversian canals appeared in 8 weeks, while it took 12 weeks needed to form matured bone tissue in control group. In conclusion, MAO titanium materials shows good biocompatibility and calcium phosphate inducement capability in vivo and could accelerate bone tissue growth and shorten the osseointegration time.

[Influence of helix angle and density on primary stability of immediately loaded dental implants: three-dimensional finite element analysis].

OBJECTIVE: To analyze effects of different thread helix angles and densities on the primary stability of immediately loaded implants using the three-dimensional finite element model analysis. METHODS: Five models of three-dimensional finite element (0.8 mm, 1.6 mm, 2.4 mm, double-threaded, and triple-threaded) were created using the commercial codes of Pro/E software, Hypermesh software, and ABAQUS software. In conditions of horizontal and vertical loading, the micro-motion of the finite element models with different thread helix angles and densities were computed with ABAQUS software. RESULTS: Concerning different thread helix angles, the micro-motion of single-threaded implant was the minimum and that of the triple-threaded was the maximum with vertical and horizontal loading. The micro-motion of doubled-threaded implant was the minimum compared with thread pitch 1.6 mm and the micro-motion of triple-threaded implant was the minimum compared with thread pitch 2.4 mm with vertical and horizontal loading. CONCLUSIONS: The thread helix angle and density of implants can greatly affect the vertical interfacial micro-motion. With increasing thread pitchs, the resistance of implant to vertical load is weakened; with increasing thread helix angle, the resistance of implant to vertical load is weakened; with increasing thread density, the resistance of implant to the vertical load is weakened.

[Diameter and length double objectives robust analysis of cylinder dental implant].

OBJECTIVE: To determine the jaw bone stress variation affected by cylinder implant diameter and length simultaneously in Ansys DesignXplorer module. METHODS: Finite element model of segment mandible with a cylinder implant was created. The range of the implant diameter (D) and length (L) were set from 2.5 mm to 5.0 mm and from 6.0 mm to 16.0 mm respectively. The maximum Von Mises stresses in jaw bone and sensitivity to D and L were evaluated. RESULTS: Under axial (buccolingual) load, when one variable equaled to median, the amplification of maximum Von Mises stresses in cortical bone and cancellous bone were 44.66% (71.32%) and 51.45% (58.50%) respectively with the D increasing. The amplification of maximum Von Mises stresses in cortical bone and cancellous bone were 45.97% (21.66%) and 52.15% (37.75%) respectively with the L increasing. When D exceeded 3.7 mm and L exceeded 10.0 mm, the response curve curvatures of maximum Von Mises stresses to L and D in jaw bone ranged from -1 to 0. And the variation of the maximum Von Mises stresses in jaw bone was more sensitive to D than to L. CONCLUSION: Stresses in jaw bone under buccolingual and axial load are apt to be affected by implant diameter and length respectively. And to a cylinder implant, the diameter exceeds 3.7 mm and length exceeds 10.0 mm are optimal selections. Diameter should pay more attention to than to length for cylinder implant. Expanding the width of the jaw bone is more important than expanding the height of the jaw bone in clinical experience.

In vitro culture and characterization of alveolar bone osteoblasts isolated from type 2 diabetics

In order to understand the mechanisms of poor osseointegration following dental implants in type 2 diabetics, it is important to study the biological properties of alveolar bone osteoblasts isolated from these patients. We collected alveolar bone chips under aseptic conditions and cultured them in vitro using the tissue explants adherent method. The biological properties of these cells were characterized using the following methods: alkaline phosphatase (ALP) chemical staining for cell viability, Alizarin red staining for osteogenic characteristics, MTT test for cell proliferation, enzyme dynamics for ALP contents, radio-immunoassay for bone gla protein (BGP) concentration, and ELISA for the concentration of type I collagen (COL-I) in the supernatant. Furthermore, we detected the adhesion ability of two types of cells from titanium slices using non-specific immunofluorescence staining and cell count. The two cell forms showed no significant difference in morphology under the same culture conditions. However, the alveolar bone osteoblasts received from type 2 diabetic patients had slower growth, lower cell activity and calcium nodule formation than the normal ones. The concentration of ALP, BGP and COL-I was lower in the supernatant of alveolar bone osteoblasts received from type 2 diabetic patients than in that received from normal subjects (P < 0.05). The alveolar bone osteoblasts obtained from type 2 diabetic patients can be successfully cultured in vitro with the same morphology and biological characteristics as those from normal patients, but with slower growth and lower concentration of specific secretion and lower combining ability with titanium than normal ones.

[Optimized thread pitch design and stress analysis of the cylinder screwed dental implant].

OBJECTIVE: To determine the optimal thread pitch for an experimental cylinder implant in Ansys Work-bench Design Xplorer environment. METHODS: Finite element models of segment jaw bone with a V-shaped thread implant were created. The thread pitch (P) was set from 0.5 mm to 1.6 mm. The maximum Equivalent stresses (EQV stresses) in jaw bone and in implant were evaluated. RESULTS: Under axial load, the amplification of maximum EQV stresses in cortical bone, cancellous bone and implant were 7.1%, 123.4% and 28.7% respectively. Under bucco-lingual load, the amplification of maximum EQV stresses in cortical bone, cancellous bone and implant were 2.8%, 28.8% and 14.9% respectively. When P exceeded 0.8 mm, the response curve curvature of maximum EQV stresses in jaw bone and in implant to P was ranged from -1 to 1. CONCLUSION: Stresses in cancellous bone are more sensitive to thread pitch than in cortical bone. Stresses in jaw bone under axial load are easier affected by thread pitch than under bucco-lingual load. Thread pitch plays a greater role in protecting dental implant under axial load than under bucco-lingual load. Thread pitch exceed 0.8 mm should be the optimal design in a cylinder implant, but oversized pitch should be avoided too.

[Influence of bicortical anchorage on the natural frequencies of dental implant].

OBJECTIVE: To investigate the influences of bicortical anchorage on values of natural frequencies of dental implants utilizing the 3-dimensional finite element analysis. METHODS: Using the commercial code of Solidworks, 3-D models of a screw-shaped dental implant and a mandibular bone segment were generated. After the 3-D implant-bone complex was meshed by ABAQUS software, effects of bicortical anchorage on the buccolingual and axial first-order natural frequencies of the implant were computed. RESULTS: Bicortical anchorage increased both the buccolingual and axial natural frequencies remarkably. As the bicortical anchorage got deeper, the frequencies correspondingly got higher. CONCLUSION: Bicortical anchorage can increase the buccolingual and axial primary stability of dental implants.