Objective: Enamel Matrix Derivative (EMDOGEIN, EMD), as porcine-derived enamel matrix proteins, has been reported to promote regeneration of periodontal tissue. In this study, we implanted the porous hydroxyapatite (HAp) carrier with EMD/propylene glycol alginate (PGA) gel into bone defects. The effect of EMD on new bone formation was histologically examined.
Methods: The bone defect (3.5 mm in diameter and 2.5 mm in depth) was prepared at the distal femoral condyles of 2-year-old rabbits. The cylindrical HAp carrier (diameter: 3.0 mm, height: 2.0 mm) had pierced straight holes whose pore size was 375 μm in diameter. We held the EMD/PGA gel and PGA gel in the straight holes of the HAp structure and implanted these HAp carriers into the bone defect. The animals were randomly divided into 4 groups: only bone defects sham operation group, HAp alone, HAp＋PGA group, and HAp＋EMD/PGA group. The rabbits were sacrificed at 2 and 8 weeks after implantation, and the femur bones were then extracted. The extracted femur bone tissue was decalcified and was then embedded in paraffin. The cross-section of the demineralized sample was stained with hematoxylin-eosin or azan staining, and histological observations of the stained samples were performed. The contact ratio of newly formed bone to the HAp surface was determined, and the thickness of new bone formed at the surrounding of the HAp carrier was measured.
Results: The new bone was formed along the HAp surface. The contact ratio of the new bone to the HAp surface and the width of the new bone formed at the HAp carrier increased by increasing the implanted period from 2 to 8 weeks. Furthermore, the regenerated osteoid tissues were replaced with the mineralized bone by remodeling at 8 weeks. However, no significant difference was observed among the three experimental groups. The application of EMD/PGA gel accelerated the production of fibrous tissue.
Conclusion: The application of the EMD allowed for the growth of fibroblast and the EMD appears to exert an influence on cells, which is compatible with improved wound healing.
In order to investigate how much the retentive force of an implant overdenture is affected by the position of the measuring force, or the type, number, setting position of the attachment, the retentive force of an implant overdenture using three kinds of attachments, i.e., clip, ball and magnet, respectively, was measured experimentally, and results were analyzed and summarized as follows.
1. In the case in which the three attachments were employed, the retentative force at the midline of the central anterior teeth and at the first molar teeth was 34.95±1.39 N and 4.18±0.34 N, respectively for the clip, 63.92±2.44 N and 12.53±0.64 N, respectively for the ball, 3.96±0.93 N and 0.84±0.25 N, respectively for the magnet. For all points measured, the value of the retentive force for the ball attachment was greatest, followed by the clip attachment, and was least for the magnet attachment (p＜0.001). In the case of the magnet, the retentive force of the implant overdenture was extremely weak compared with the clip and ball attachments.
2. In the case of two ball-attachments embedded at both edges of the dental arch form, the retentive force at the midline of the central anterior teeth and at the first molar teeth was 32.58±0.51 N and 14.23±0.36 N, respectively, and in the case of one ball-attachment embedded at the midline of the central anterior teeth of the dental arch form, the force was 25.19±2.19 N and 10.56±0.57 N, respectively. Consequently, the retentive force of both the two or one ball-attachment employed was found to be clinically sufficient to secure the implant overdenture.
3. The retentive force was affected by not only the position of the measuring force but also by the type, number, and setting position of the attachments.
Quantity and quality of the bone where dental implants are installed affect the outcome of the treatment. The purpose of the present study is to clarify the effects of sex differences and menopause on the bone of a partially edentulous molar region of the mandible.
The mandibles of 91 patients, 29 males and 62 females including 38 postmenopausal women, were analyzed with CT scans. The trabecular width (TW), cortical width (CW) and bone mineral density of the trabecular bone (BMD) were obtained.
The results were as follows:
1. Male BMD was higher than female BMD, and the BMD of menopausal women was lower than that of premenopausal women.
2. Female TW was larger than male TW, whereas female CW was smaller than male CW.
3. In all patients, BMD correlated negatively with TW and BMD correlated positively with CW.
4. Among the male patients, BMD correlated with neither TW nor CW.
5. Among the female patients, BMD correlated negatively with TW, whereas BMD correlated positively with CW.
6. In premenopausal women, BMD correlated negatively with TW, whereas BMD did not correlate with CW.
7. In postmenopausal women, BMD correlated with neither TW nor CW.
These results demonstrated that sex differences and the menopausal state affect mandible bone condition as well as the condition of the vertebrae and bones of legs and arms.
On the basis of data obtained in a cell culture study on the ingrowth speed of bone formative group cells into Ti-Zr porous blocks, two kinds of implants with average pore sizes of 95 μm and 149 μm were used in this experiment. The Ti-Zr porous implants were installed in a beagleʼs upper and lower jawbones to investigate bone occupancy in the pore and bone bonding strength at 5 and 30 weeks post-implantation.
The pore size dependency on the bone occupancy and bonding strength were clearly proved by histometric investigations, statistically compared using ANOVA.5 weeks post-implantation, both pore sizes of 95 μm and 149 μm could not reach the adequate bone bonding strength of 600 N required to keep the implant fixed under functional biting. However, when the 149 μm pore size implants were immersed and cultured for 2 weeks in the medium (MEM＋10% calf serum) with bone formative group cells derived from bone marrow of the host dogʼs femur before the implantation, the implants demonstrated higher bone occupancy in the pore and higher bone bonding strength of 624 N 5 weeks postimplantation compared with 360 N of the 149 μm pore size implants without pretreatment of bone formative group cells. If early loading after implantation is required, it may be effective to treat the porous implant with 14-days-cultivated bone formative cells derived from the patientʼs bone.
Resonance vibration frequency analysis (RFA) is widely acknowledged as a commercially available technique has made it possible to evaluate implant stability easily and nondestructively. The stability of an implant is indicated as the implant stability quotient (ISQ) as measured using the OsstellTM or OsstellTM mentor.
The purpose of this study was to examine what affected the ISQ value of the OsstellTM mentor which was a new wireless resonance frequency analyzer. We experimentally installed implants in a mandibular skeletal model made of polyurethane. The ISQ values were measured under various conditions in which the distances between the transducer and the measuring probe, the direction of the measuring probe, and the connecting situations of the transducer were varied. The ISQ values determined by the OsstellTM and OsstellTM mentors were compared, and the factors which influenced the ISQ values were assessed.
In addition, four patients treated with an implant prosthesis at Tokushima University Hospital were randomly selected for this study.Eight implants (1 in the maxilla, 7 in mandibles) were measured using the OsstellTM and OsstellTM mentors by two measurers. The ISQ values from both devices were compared by calculating correlation analyses and drawing scatterplots, and conducting regression analysis.
The results are summarized as follows:
1. The ISQ values obtained using the OsstellTM mentor were affected by the distances between the transducer and the probe, how the transducer was connected, as well as by the type of materials lying between the implant and transducer.
2. Compared with the ISQ values for both devices, there was an obvious correlation.
3. The ISQ value range for the OsstellTM mentor was smaller than that for the OsstellTM mentor.
4. There were no statistical differences in the ISQ values of the OsstellTM mentor between the two measurers.
The results of this study suggest that there is agreement between both devices for evaluating implant stability and that the OsstellTM mentor is the more precise and easier device to use.
The aim of this study was to qualify and differentiate between the new bones formed around hydroxyapatite-blasted implants and the cortical bone.
Evaluation of bone substance was carried out using non-decalcified tibia after 1, 2 and 4 weeks implantation by polarized light microscopy, parametric X-ray radiation (PXR) and position sensitive proportional countermicro-X-ray-diffractometer (PSPC-Micro-XRD).
Several parts of remarkably high birefringence in the new bone were revealed by the polarized light microscopy. The new bones formed around implants were compared among 1, 2 and 4 weeks after implantation: the volume of the new bone increased with time, and the Haversian lamella appeared after 4 weeks. In PXR,the cortical bone was generally observed to be radiopaque. The attached layer of the newly formed bone covering the implant was observed to be radiopaque, and its radiopacity was generally lower but similar to that of the compact bone. The full width at half maximum (FWHM) value of apatite (Ap) 002 in micro-XRD charts showed that crystallinity of the new bones increased from 1 to 2 weeks and slightly increased from 2 to 4 weeks. In this study, polarized light microscopy revealed the presence of new bones which were hardly shown by PXR. PXR showed calcification of new bone. Thus, the new bones formed around implants can be evaluated more exactly by combining these three analytical techniques.
Recently, titanium mini screw implants have been utilized as the anchor for various orthodontic treatments. This method has several advantages such as a decrease in the treatment period, less discomfort for the patient, and reduced anchor loss which usually occurs among the natural anchor teeth. This method also has a number of problems such as the occurrence of disintegration, inflammation of the surrounding soft tissues, and screw fractures.
In this study 65 mini screw type implants applied in 26 patients were analyzed in terms of problems related to the location of the installation of the implants.
The following results were obtained: Problems were found in 17 implants (26.2%). The most frequent problem was inflammation around the implants (52.9%) in the maxillary posterior region. Fractures of the screw were also observed during the removable of screws; however, no screw fractures were found during the orthodontic treatment period.
These results suggest that further improvement in the installation method for mini screw type orthodontic implants are indicated.
Purpose: Unlike natural teeth, which are surrounded by a periodontal membrane, osseointegrated implants bond directly with bone, resulting in a difference in their displaceability. Accordingly, in partially edentulous patients with implants, it is important to consider the biomechanical and functional aspects of the occlusion of any prostheses. This study investigated basic features of occlusions on prostheses supported by implants in partially edentulous patients.
Methods: Subjects consisted of 18 patients (57.6±12.8 years old) wearing 2～3 implants in unilateral maxillary or mandibular posterior free-end saddles for 3.4±2.6 years. Occlusal force was measured with pressure sensitive film (Dental Prescale® 50H Type R) at several levels of voluntary clenching. The mandibular dental arch was divided into four regions 1) IR: region of prosthesis supported by implants; 2) FR: region of residual teeth anterior to implants on the implanted side; 3) OR: region of residual teeth corresponding with implants on the opposite side; and 4) OFR: region of residual teeth anterior to OR. The occlusal force on each region and its ratio to total occlusal force (%) were calculated. In addition, a regression line was drawn with total occlusal force on the horizontal axis and occlusal force ratio on the vertical axis. The significance of differences was tested between the gradient of the regression line and gradient 0, which indicated that the occlusal force ratio was constant irrespective of any increase in total occlusal force.
Results and Discussion: Total occlusal force at maximum clenching and the asymmetry index were equivalent with those of a healthy dentition. In one group of patients, the occlusal force ratio at IR was constant irrespective of the level of occlusal force, while in another group the ratio varied with the level of occlusal force.
In this second group, there was no initial occlusal contact at IR, and the occlusal force on IR during maximum clenching was significantly lower than that at OR. Furthermore, there were more subjects in this group whose occlusal force ratio at FR changed with the level of occlusal force than in the first group. Variation in the occlusal force ratio at FR showed a pattern to compensate for insufficient occlusal force at IR.
Purpose: The purpose of this study was to examine the patient evaluation of the outcome in 1,842 patients who received implant-supported prostheses.
Materials and Methods: Patients were treated surgically and underwent prosthetic rehabilitation by dentists belong to the Kyushu Implant Research Group.Two thousand five hundred fifteen patients who received implant-therapy loaded over one year were sent a questionnaire consisting of 28 questions regarding phonetics and satisfaction.
Results and Conclusions: A total of 1,842 patients (73.2%) returned the questionnaire. Sixty-three percent of patients had adequate counselling before implant treatment. Ninety-eight percent of patients were satisfied with their oral function after treatment, and 79% reported having no trouble. Seventy-five percent of patients found implant-supported rehabilitation to be very expensive, and 72% felt that their implants should survive for 20 years in function. Ninety-seven percent patients understood the necessity of periodical checkups and 88% underwent regular checkups.