Contact guidance is the tendency of cells to be guided by the shape of the substratum to which they are attached. Although contact guidance has been exhibited by many kinds of cells, contact guidance of osteoclasts on grooved substrata has not been examined. The present study investigated how osteoclasts are guided by grooved substrata. Four types of titanium-coated grooved substrata were used. Osteoclast precursor cells were placed on the substrata and stimulated with agents promoting differentiation of osteoclasts according to the supplier's protocol. Observation with a stereoscopic microscope confirmed the cells were positively stained with Tartrate- Resistant Acid Phosphatase (TRAP) on the titanium substrata, indicating they were osteoclastic cells. SEM observation revealed the osteoclastic cells were polygonal or round in shape, arranged in a disorganized pattern on the smooth substratum. The orientation index (OI) for contact guidance was calculated as the perpendicular length divided by horizontal length. The cells on the micro substratum (0.2-0.4 μm-deep groove) showed a significantly lower OI than those on the narrow substratum (1.5 μm-deep grooves with a 3 mm pitch comprising a 1 μm-wide groove and a 2 μm-wide ridge) or the wide substratum (1.5 μm-deep grooves with a 6 mm pitch comprising a 2 μm-wide groove and a 4 μm-wide ridge) at 5 days. These findings indicate that a significantly lower proportion of osteoclasts were aligned on the micro substratum than on the narrow or wide substrata.
In conclusion, the present study demonstrated that the grooved surface of the substratum can control the orientation of osteoclasts. Peri-implant bone remodeling requires coordinated activity by osteoclasts and osteoblasts. These findings may lead to changes in the surface design of implants to promote improved bone remodeling around the implant.
The purpose of this study was to evaluate stress analysis of a magnet-retained mini-implant overdenture on an in vitro mandibular model. Mini implants less than 3.0 mm in diameter have been used as not only provisional use, but also permanent use to support overdentures.
Four mini implants (MagDen Fixture MFI4010RF, Shinwon Dental, Seoul, Korea) were placed in edentulous regions between bilateral canines in an acrylic resin mandibular model and the abutments (MagDen Keeper MFK4020, Shinwon Dental, Seoul, Korea) for magnet attachments were used. Seven strain gauges were attached on the resin surface around the right side of two mini implants. The surface of the model was covered with silicone impression material to simulate oral mucosa and an experimental complete denture was placed on the model. A vertical force of 50 N was applied to either one of the premolar, first molar and second molar of the experimental denture using a universal testing machine.
When four mini implants were supported, compressive strains were caused at the lingual side of the distal mini implant. The more posterior the loading point was, the lower the strain around the implant was generally. Although tensile strain was caused at the buccal side of the mesial mini implant, it decreased at the moment when compressive strain arose. When four implants were supported, the strain around the mini implants was distributed more evenly than those in the two implant-supported ones. The influence of implant positioning was examined by removing either two mesial or two distal attachments in the four mini implants. The maximum strain in two mesial implant-supported attachments was smaller than that in two distal implant-supported attachments.
In many cases of dental implant surgery, especially extensive bone defects, alveolar ridge augmentation is necessary. Iliac bone marrow-derived mesenchymal stem cells have recently been used for various tissue regeneration therapies. However, these stem cells do not seem a good source for alveolar bone augmentation. Mesenchymal stromal cells that have osteogenetic activity and have the potential to be harvested from alveolar bone marrow might be a candidate source for regenerating alveolar bone, even though dentists have not harvested the cells outside of the mouth. However, very little bone marrow aspirates from alveolar bone, and the method for achieving stable bone marrow aspiration and culture technique are not well established. Furthermore, the characteristics of cells cultured from bone marrow vary greatly among subjects or collection site. Accordingly, the authors report a very low-invasive method to aspirate alveolar bone marrow during implant surgery without any additional invasion. The authors cultured marrow stromal cells from two independent cases and analyzed cell surface antigen and calcification ability in vitro and osteogenetic activity in vivo. The authors successfully cultured 1.6-6.3×1011 cells for 73-77 days of culture from a small amount of marrow aspirates. The Hounsfield unit of each bone marrow aspirate site, the calcification speed of the stromal cells in vitro , and HLADR antigen expression of the cells were different. However, both stromal cells formed new bone on mouse parietal bone.
The purpose of this study was to determine whether clinical success can be achieved with Brånemark system short implants (Nobel Biocare) three years after the placement of implants.
One hundred and thirteen short implants (＜10 mm) were installed:42 implants with smooth surfaces and 71 implants with rough surfaces. Twenty-two implants were installed in the maxilla, and 91 implants in the mandible. All implants were submerged. A chi-square test was used to evaluate the significance of implant loss of short implants with implants longer than 10 mm.
There was no significant difference in the failure rates between short implants and implants longer than 10 mm. Among smooth surface implants, the failure rate of short implants was significantly higher than that of implants longer than 10 mm, but among rough surface implants, no significant difference in the failure rates was observed between short implants and implants longer than 10 mm. These results demonstrated that short implants with rough surfaces were as useful as implants longer than 10 mm.
Objective: Several dental implant placements in the maxillary molar region currently need sinus elevation due to alveolar bone resorption and maxillary sinus expansion. Previous clinical studies have reported that implants with sinus elevation have survival rates within the range of 90 to 97.6%, suggesting its high degree of stability. This study examined risk factors of dental implants with sinus elevation.
Subjects and methods: The subjects were 234 patients (82 males and 152 females, mean age:55.3 years) who underwent sinus elevation between 2000 and 2011. During the observation period (1-12 years), we examined the following parameters such as implant survival rates, frequency of implant loss, causes of implant loss, and general and local factors related to implant loss.
Results: Implants were lost in 15 of the 234 cases, indicating a survival rate of 93.6%. In terms of frequency of implant loss, the implant survival rate of less than one year after sinus elevation was 97.3%, whereas the survival rate more than three years after sinus elevation was 96.3%. The implant survival rate in simultaneous implantation was 96.4%, whereas the survival rate in delayed implantation was 96.3%, thus showing no differences in survival rates between the two procedures. Statistically significant differences were observed in cases where simultaneous implantation was performed on patients with respiratory illnesses, as well as in cases where cover screw exposure was observed post-operatively.
Discussion and Conclusion: Approximately 70% of implant losses occurred less than one year after sinus elevation, suggesting that comprehensive monitoring plays a major role in preventing secondary infections and in improving recovery time. Monitoring may also decrease the number of risk factors associated with sinus elevation, such as respiratory illness and postoperative cover screw exposure.
Purpose: The aim of this study was to establish bone components, starting time of new bone formation, quality, quantity and maturation of new bone at the regenerated site with reference to sinus lift surgery by histo-pathological analysis.
Materials and Method: The study group consisted of 81 core biopsy specimens of 2 mm in diameter and 8 mm in length taken by using a trephine bur, of 38 sinus lifts from 38 patients. These were divided into 10 groups: 61-90 days group, 91-120 days group, 121-150 days group, 151-180 days group, 181-210 days group, 211-240 days group, 241-270 days group, 271-300 days group, 301-330 days group and 331-365 days group after surgery. All core specimens were prepared for HE staining and antiPCNA antibody staining. New bone formation, new bone quality and quantity, mature bone and soft tissue were analyzed with the bone morphometrical method and the PCNA labeling index were calculated for all groups.
Results: 1.The formation of new bone was observed in the regenerated site of the sinus lift in the 61-90 days group. 2.The maturation of new bone in the regenerated site was observed in the 91-120 days group. 3.A large quantity of new bone in the regenerated site was observed in the 121-300 days group compared with the other groups, but only a small quantity of mature new bone was observed and the maturation of new bone was delayed in the regenerated site of the sinus lift. 4.A large volume of total bone area was observed compared with the other groups and was established in the 271-365 days group. 5.The PCNA labeling index was observed in the regenerated site of the sinus lift in all groups.
Conclusion: Active new bone formation was observed in the long term.
Successful dental implant treatments have been popular and widely applied to many cases of missing teeth, so installing implants could become a promising solution as a prosthodontic tool. However, it can occasionally be difficult not only to achieve aesthetic acceptability but also to recover the oral function with the fixed superstructures because of severe bone loss or recession of keratinized junctional epithelium. Implant-supported overdentures can allow more spaces for alignment of artificial teeth, which may give aesthetic and functional satisfaction with their effective retention, support and stability. Similarly, other versions of implant-supported partial dentures, possibly equipped with clasps, are expected to bring efficacy to partially missing dentitions. In this clinical report, an implant-supported partial denture was delivered to a partially missing maxillary dentition over a bar attachment.
A 59-year-old woman, who had suffered from masticatory malfunction and cosmetic disturbance, was treated with an implant-supported partial denture with two cast clasps and occlusal rests over a bar attachment connected to four dental implants. Implant-supported partial dentures are supposed to support restitution of occlusion and aesthetics, sharing the functions with residual teeth utilized as abutments. These prostheses have advantages such that the position of artificial teeth can be more flexible, that cosmetic problems can be rectified, and that bone reduction and that concern over epithelial recession and prosthetic stability can be overcome by prostheses. Furthermore, implant-supported partial dentures that are removable would be easier for patients to handle than fixed prostheses and enable them to maintain their oral hygiene.
In this clinical application of an implant-supported partial denture, the patient acquired functional and cosmetic recovery, and there have been no accidental malfunctions for three years since the denture installation.
Widely ranging malformations of lips, alveolar bone or palate may often make it difficult to reconstitute the masticatory function with prostheses, especially with dental implants. However, there have been few reports on the application of dental implants in such cases as alveolar clefts. In this report, two dental implants and magnetic attachments were installed in the maxillary molar region. And the surgery was undertaken without any additional bone graft at the alveolar cleft site since the compromised region was anticipated to rarely host the graft because of less vascularity of the surrounding tissues.
The patient was a 48-year-old woman with an alveolar cleft on the left side and oligodontia of the anterior region of the maxilla. After the maxillary left first and second molars had functioned as abutments of the maxillofacial prosthesis over 30 years, the loss of these teeth caused a significant decrease of denture retention. Although three conus crowns of the telescopic system of the denture still remained in the canine and the premolar regions, severe mobility of all three teeth was found. Most of the initially grafted bone from both sides of the iliac crests had been degraded and its residual bone volume was insufficient for implant placement, especially in the anterior region. Although the additional vascularized bone block was necessary to acquire abundant bone volume to stabilize dental implants in the anterior region, we, followed by the patient's refusal of another graft operation, chose another procedure for inserting two implants in not the anterior but the molar region accompanied by magnetic attachments on them to support and retain the existing denture in spite of the complex form of the cleft jaw. Although recent case reports and systematic reviews described the effect of magnetic attachment for implant-supported overdenture( IOD), most cases demonstrate only mandibular trials or maxillary anterior applications of IOD. In the present case, magnetic attachments were applied at the posterior region of the maxilla, and then contributed to improvement of denture retention, recovery of masticatory performance and the pronunciations and the patient's satisfaction in a 3-year prognosis. Generally, the posterior region is difficult for both the patients and the operators to approach because of the narrowed oral cavity with the post-operative mucosal scar; therefore, the simple shape of the keepers can be more advantageous for the surgical and prosthetic operations and daily self-care than any other types of IOD attachments.
Thus, this clinical example indicated that the magnetic attachments on the posterior implants as an IOD constitution were appropriate to not only restriction of their delivery space and retention acquisition of the denture but also maintaining oral hygiene.
For many general dentists, dental implants have become an increasingly common treatment option for missing dentition. On the other hand, with the population becoming increasingly older worldwide, general dentists will be confronted with patients who have complex medical and social histories who desire tooth replacement therapy.
We performed a questionnaire survey of dentists to understand the present conditions of implant patients who were then followed up in this study. The questionnaire was sent to those who attended the specialist education lecture at the 42nd Annual Meeting of the nonprofit foundation, Japanese Society of Oral Implantology. The questions concerned the overall implant treatment, situation of nursing care patients who received implant treatment, and problems. Regarding the overall implant treatment, the most common age group was patients aged 40 to 60 years old, occupying approximately 90% of all patients.
About half of the dentists had experienced interruption of implant treatment regardless of treatment period, and the causes included a malignant tumor, cerebrovascular disorder, senility, and dementia.
Regarding nursing care patients who received implant treatment, about half of the dentists had experienced the treatment of a patient who had an implant through house calls. Furthermore, it was found that these patients often had difficulties with their own mouth care.
This investigation clarified the present state of experience of implant treatment. It is certain that implant treatment is a very useful treatment, but education for the family and the care staff will be necessary because it is difficult for a dentist to treat all patients by house calls. It is also important for dentists and the Japanese Society of Oral Implantology to make guidelines for such situations.
We are now living in an age where preoperative examinations of oral implants are no longer limited to use of CT data in visual examinations of diagnostic images: through fabrication of computer models, the shape of the jawbone beneath the mucous membrane can also be understood through physical touch. This report uses case studies to present the new methodology and benefits of computerized bone models made with a 3D plaster printer.
The technique was first used in a maxillary sinus floor augmentation procedure. Through the computerized bone model, we were able to understand the unique anatomical features of the patient. Further, because the model was made with plaster material, we were able to very closely simulate the feel of cutting in the actual surgery, enabling pre-surgery selection of implements and precise preparation for the surgical procedure. Next, we used the technique to fabricate provisional restorations for immediate loading in open flap surgery on an edentulous jaw. After connecting the edentulous jaw bone surface, with information gleaned from CT images, with the occlusal surface for the optimally arranged complete dentures, simultaneous fabrication made the previously difficult attachment of the computerized bone model of the edentulous jaw to the articulator possible, and we were able to prefabricate the provisional restorations for the implant.
The examples above show that computer models fabricated through 3D plaster printing make possible safe, reliable, surgical procedures. Further, highly precise fabrication of provisional restorations for prostheses for edentulous jaws is also possible, which clearly shows the notable clinical usefulness of the technique.
Geriatric patients often require oral implants to recover oral function due to missing teeth. However, oral implant surgery requires more care than general complications, especially in geriatric patients, who sometimes develop severe complications during surgery. We investigated the incidence of general complications including perioperative oral implant procedures carried out at a private dental office.
In this study, 228 patients who underwent implant surgery were enrolled for evaluation. All patients underwent implant placement surgery under intravenous sedation.
The patients were divided into four groups based on the 10th revision of the International Statistical Classification of Diseases and Related Health Problems(ICD-10) in order to categorize patients according to their health condition as determined from a preoperative interview and the incidence of cardiac disease during the perioperative period. This evaluation revealed that oral implant patients were suffering from various diseases. Out of the 228 patients evaluated, 141 were found to be without any general diseases from self reports, and 87 had various general diseases. Fifty-two patients had heart diseases. Out of the 228 patients, 158 showed no evidence of heart or metabolic disease; however, certain findings related to cardiac disease were detected in 28 patients during dental implant surgery.
The results of this evaluation suggest that it is critical to observe and ascertain changes in the general conditions of geriatric patients during implant surgery.