With the spread of implant prosthesis, the importance of occlusion has become known. It is considered that the occlusion on the implant prosthesis should be grasped not only morphologically but also functionally.
The purpose of this study was to clarify the characteristics of chewing rhythm on implant prosthesis and to enhance examination and diagnosis thereof. Seven patients with implant prosthesis in the molar region were selected as the test group, and 20 persons who have individual normal occlusion were selected as the control group. The chewing movements were recorded and analyzed with Sirognathograph Analyzing System III. Then the results of the two groups were comparatively examined.
The results were as follows:
1. On implant side chewing as compared with that of the control group, increase in the duration of the occluding phase and cycle time was observed. While the ratio of the duration of the opening and closing phase to cycle time decreased, the ratio of the duration of occluding phase to cycle time increased. In addition, the stability of the duration of each phase was lower than that of the control group.
2. On segmental chewing in the implant region as compared with that of the control group, increase in the duration of the occluding phase was observed. While the ratio of the duration of the opening phase to cycle time decreased, the ratio of the duration of the occluding phase to cycle time increased.
3. On segmental chewing in the implant region as compared with implant side chewing, increase in the ratio of the duration of the closing phase to cycle time was observed.
In the 1960 s, the concept of osseointegration was suggested by Prof. Brånemark. Since then, its application in dental implant therapy has made rapid progress. In this investigation, three different types of endosseous implant systems were compared and examined in terms of their clinical survival rates.
From 1989 to 1995, 3 different types of implant system were used in 212 patients. These types were a 2-stage Ti-screw type(Ti-S), a 1-stage Ti-plasma hollow cylinder type(Tip-C), and a 2-stage HA-coated cylinder type (HAp-C).
The cumulative survival rate of each implant system after 5 years is Ti-S 93.8%, Tip-C 93.5%, HAp-C 98.3% respectively. As for the implant body length (mm) and the quality of bone (Lekholm＆Zarb bone density classification) in which the implants were placed are compiled, significant differences in survival rate are apparent among screw, hollow-cylinder, and HA-coated cylinder type implant systems.
As for achieving osseointegration, the cylinder type implant is more effective than the screw type, especially when placed in low quality bone. However, the screw type implant system is more effective than the cylinder for maintaining osseointegration.
As a result, when selecting implant systems, it is necessary to utilize panoramic radiographs in order to assess the availability of bone to determine the length of the implant as well as tomography for diagnosis and select the appropriate implant system.
Rapid replacement of bone by bone filling material in the region lacking bone is quite desirable. Biocompatible pH value and bone filling material composition are necessary. Easy to handle bone filling material is needed. Therefore, in the present study, the relationships among various ratios of powder to chitosan sol and setting tune, pH value, compressive strength and dissolution of the elements were observed.
The results were as follows:
1. An increase in the ratio of powder to chitosan sol resulted in a shortened setting time.
2. An increase in the ratio of powder to chitosan sol resulted in a higher pH value.
3. Compressive strength was influenced by the ratio of powder to chitosan sol.
4. By increasing the ratio of powder to chitosan sol, the dissolution of calcium and silicon increased.
5. These findings indicated that a ratio of powder to chitosan sol of 0.67/2.2 by weight eras optimum for preparation of bone filling material.
The release of metal ions in vivo is often accompanied by allergic reaction. Therefore, it is desirable to use the same metal in the oral cavity because of electrochemistry. With this in mind, titanium, for example, is recommended as an implant as well as for a prosthesis. With laser welding, it is possible to join parts by the self-welding of the metal parts. However, laser welding induces volume reduction during the welding process. This study was conducted to investigate the relationship between titanium foil and volume reduction during the welding process. The results were as follows:
1. Laser-welded titanium plate produced porosity both on the surface and in the cross-section.
2. The insertion of a titanium foil was effective in preventing volume reduction during the welding process. In the experiment, no porosity was observed on the surface.
3. Greater bending strength was generally observed for self-welding titanium plate using 30 μm titanium foil. However, the bending strength decreased as the thickness of titanium foil was increased. Laser-welded titanium plate decreased in elasticity, with hardness of the welded area being greater than that the original area.
As an ideal dental material and consideration of electrochemistry, titanium employed both as an implant and a prosthesis will have good results. Using titanium, this study was conducted to investigate the relationship between bonding strength of dental adhesives and surface roughness and thermal cycling. The results were as follows:
1. Zinc phosphate cement did not adhere to titanium plate.
2. The bond of polycarboxylate cement and Panavia 21 to the titanium was strong.
3. Polycarboxylate cement shrank when it was heated, while Panavia 21 cement expanded.
4. Polycarboxylate cement showed a tendency to decrease in adhesive strength to titanium plate after thermal cycling.
5. Panavia 21 showed considerable decrease in adhesive strength to titanium plate after thermal cycling.
6. The adhesive strength of zinc phosphate cement was influenced by the roughness of the titanium surface.
Continuous monitoring of vital signs is important for ensuring the safety of patients undergoing invasive procedures during implant therapy. Medical engineering techniques were used to develop a video overlay monitoring system (VOLMS) that permitted the clinical use of a commercially available monitor and the documentation of detailed intraoperative records. This system uses a personal computer and superimposer to analyze serial data output from the monitor and to superimpose vital sign data, as well as the corresponding date and time, onto the intraoperative image displayed on a television monitor. The system also allows the storage and transfer of these images.
Vital sign data displayed on the intraoperative image include systolic blood pressure, mean blood pressure, diastolic blood pressure, pulse rate obtained piezoelectrically from cuff vibration, pulse rate obtained photoelectrically from a fingertip, and arterial oxygen saturation. In addition, during measurement of blood pressure the rate pressure product (RPP) is calculated and output. When blood pressure is not being measured, the operating system software is revised to permit display of the arterial oxygen saturation and the pulse rate obtained from the fingertip probe once per minute.
The use of this system for implant therapy enabled not only the operator but also the patient's guardian to confirm the patient's vital signs. In addition, the recorded videotape serves as a paperless intraoperative record that can provide abundant information.
As for the teeth that periodontal tissue was lost extensively by periodontal disease, alveolar ridge produces remarkable absorption by tooth extraction, and there is much that it becomes disadvantagenus habitat when treats afterward. So, in this study, the bone defect model which had buccal dehiscence pattern bone defect found with was made, and we referred about depression effect of alveolar ridge absorption at having applied atelo-collagen sponge in tooth extraction socket.
Fourteen mongrel adult dogs were used. Went to root apex from top of buccal bone, and made buccal dehiscence pattern bone defect of 5 mm deep artificially after raised full thickness flap buccal gingiva in the first molar of lower jaw both sides, and extracted a tooth. Atelo-collagen sponge was implanted in tooth extraction socket in experimental group, and the control group wasn't implanted. And single suture was performed sewed 2 places at interdental papilla after having done reposition of gingival flap. The after an operation did ablution sterilization of wound by chlorhexidine. Impression of alveolar ridge was performed after operation for 24 weeks for 12 weeks, and sacrified it.
Evaluation method analyzed model for measurement provided with impression making, in addition, the examination was observed histopathologically. Model assay did variate of alveolar ridge, width of profile from buccal to the lingua side and each of area on the basis of constant basis and measured it and examined each. As for experimental group and control group, process of good healing was observed. At compared experimental group with control group after operation in 24 weeks, the variate of alveolar ridge showed small value in significance. And both showed big value in significance with experimental group as a result of having measured width and an area of alveolar ridge. In observation of histology, as for control group, collapse of alveolar ridge was found conspicuously, and, as for experimental group, corticalization of bone was good, and the collapse of wound was restrained for it.
From these results, it was suggested that atelo-collagen sponge was effective.
The purpose of this study was to investigate the characteristics of mineralization of new bone tissues in the space created by barrier membrane.Defects were made in the cortical bone of rat tibias. An e-PTFE membrane was applied to the defect and a control defect was not covered with a membrane. Calcein was injected at 6, 8, and 10 days after the experiment and sacrificed at 48 hours after the injection. Villanueva bone satining was performed before observing by confocal laser scanning microscopy. Two labeling styles of mineralization by calcein were detected. One type of labeling was a diffuse type which detected entire new bones diffusely and the other was a peripheral type which detected only the periphery of new bones. At 6 days in both experimental and control groups, only the diffuse type was seen. At 10 days in the experimental group, calcein was detected only periphery. At 10 days in the control group, however, calcein was detected peripherally in the lower portion but diffuse in the upper portion. From these results, it was suggested that the mineralization using the GBR method accelerates the mineralization in both upper and lower portions.
Hydroxyapatite(HA)-coated implant has a better biocompatibility than titanium and can lead to the biointegration between bone tissues and implants. Most of HA coated implants show porous structures on them due to the plasma coating. Little reports regarding cell behaviour on the porous HA has been shown. Therefore, the present study observed the morphological findings of the cells plated on the implant by SEM.
SEM observations showed porous structures on the surface of the implant and stratified structure on the cross section of it.
The osteoblast-like cells (MC 3 T 3-E 1) attached and spreaded well on the porous HA as well as smooth titanium. On the porous HA, the cells bridged among apical regions of the rough surface with numerous philopodia. The concept of the two-center effect might explain the bridging phenomenon.
Mandibular reconstruction is performed with free bone grafts of the scapula, ilium, fibula, and ribs with vascular pedicles. Osseointegrated implants are currently set in the reconstructed mandible for functional restoration. In this study, vascularized bone grafts appropriate for mandibular reconstruction were evaluated for subsequent implant grafting in the reconstructed mandible. The cross sectional internal structures of the maxilla and mandible, as well as the scapula, ilium, fibula, and ribs, which were used as vascularized bone grafts, were examined by scanning electron microscopy, and their bone morphometric features were compared. The total cross sectional area of the bone and the area of the mineralized part of the bone were measured as the total bone tissue and the total mineralized bone respectively, and the percentage of mineralized bone in the total bone tissue was calculated. The following observations were made by comparison of these bone morphometric parameters in various donor bones with those in the maxilla and mandible.
The results were as follows:
1. The total amount of bone tissue is a parameter of the amount of bone. It was the largest in the ilium, in which it was comparable to that of the mandible, followed by the scapula, fibula, and ribs in that order.
2. The percentage of mineralized bone in the total bone tissue was 38.38% in the maxilla and 63.36% in the mandible, and the difference in the percentage of mineralized bone was considered to be a factor in the difference in the success rate of implant surgery between the maxilla and mandible.
3. Among the bone grafts used for mandibular reconstruction, the percentage of mineralized bone was the highest in the fibula followed by the scapula, ilium, and ribs in that order. The ilium, which is used frequently for reconstruction surgery, had a low percentage of mineralized bone.
4. The percentage of mineralized bone decreased with age in the maxilla, scapula, ilium, fibula, and ribs, but it did not change with age in the mandible.
5. The ribs were considered from their low total amount of bone tissue and percentage of mineralized bone to have inadequate strength as the base of implants for restoration of masticatory function.
It has been reported that no less than 1 mm crest bone width around implants, on buccal and lingual sides, is indispensable for success in osseointegrated implants. However, dentists are often confronted with clinical cases where there is a narrow alveolar crest bone.
In such cases, the split crest technique, in which the alveolar crest bone is intentionally split into the buccal and lingual side to expand the ridge, is used and implants are simultaneously inserted. It is considered that this technique can increase the indication of implants and shorten the treatment period.
A clinical evaluation of 17 cases (including 28 implants) involving the split crest technique was done. Periodontal evaluations were done using the probing depth, the attachment gingiva width, the periotron test value, the mobility of implants by perio test, the bone width by bone-mapping, and the bone level surrounding implants by radiography.
Favorable results were obtained in all of these evaluations; therefore, it was concluded that the split crest technique is an effective method with wider applicability than conventional methods.
A combination of autogenous iliac crest bone graft and Branemark implants was used in 11 patients with severely resorbed maxillae. The survival rates of putting implants were estimated in the size of implants and types of the bone graft.
The follow-up period ranged from 5 to 56 months. An 89.5% survival rate was recorded in this study. This result suggested that the combination of an autogenous bone graft and Brånemark implants is an acceptable procedure for the severely atrophied maxillae.
In order to compare an overdenture with a bone-anchored full bridge clinically, a prosthetic appliance was applied respectively to two patients who have an edentulous mandible with some implants. As for investigative items, for the operation period, the method of inserting and removing their prosthesis, their recovery, repair of the prosthesis, their food intake after wearing the prosthesis, plaques growing on the prosthesis and measures to clean,the cost of procedures, and their clinical outcome were observed.
Integral Implant (Calcitek Inc., U.S.A.) of 3.25 mm diameter and 8 mm or 10 mm in length, which was inserted in the usual manner into the mandible under infiltration anesthesia, was used.
The results were as follows.
The patients could eat food easier after the implant operation than before the operation both in case 1 (overdenture) and in case 2 (bone-anchored full bridge), having achieved better occlusion.
The operation period of case 1 was almost one-third of that of case 2.
The patient himself inserted and removed the prosthetic appliance in case 1, while the operator inserted and removed it in case 2.
Both of the patients recovered in seven months by using a temporary denture.
The cost of case 1 was about one-third of that of case 2.
Since the working models and temporary denture of cases 1 and 2 remain with us, the prosthetic appliances are relatively easy to repair.
The prosthetic appliance is removable in case 1, hence it can be kept cleaner than that of case 2.
In this paper, four cases of autogenous tooth transplantation using various kinds of maxillary and/or mandibular third molars were described. The patients ranged from 33 to 58 years old; two were males and two females. Donor teeth were two impacted and two erupted teeth.
Erupted donor teeth were jiggled, and root canal treatment was done before transplantation. Root canal treatment of impacted donor teeth was done after transplantation. Donor teeth were extracted so carefully as to avoid damage to the periodontal ligament. Donor teeth were transplanted to the prepared alveolus, and the gingival flap was sutured.
The transplanted tooth was splinted for 2～3 weeks, and the provisional restoration period was 3～5 months. Then final prosthetic treatment of the transplanted teeth was done.
For two years postoperatively, remodeling of the marginal bone adjusted to the root and normal periodontal membrane-like structure was found by radiographic analysis in both cases. However, two teeth showed abnormal percussion sound and non-physiological mobility. No sign of root resorption was recognized by radiographs. It was considered that there was a possibility of ankylosis of donor teeth.
Recently, it has become possible to obtain various information from our own room by using a computer network system. Dentists should also obtain the latest information which will be very useful in clinical procedures. Therefore, dentists must become accustomed to operating the network system and retrieving desired literatures.
In this report, methods to retrieve desired literature was introduced. Literatures written in English were retrieved from the database of MEDLINE on Internet, in Japanese to the database of Igakucyuouzasshi on CD-ROM. Details of the procedures to access MEDLINE database and explore literatures about dental implant were reported.