There have been many studies reporting that newly formed bone around implants is spongy bone. However, although the morphology is reported as being like spongy bone, it is difficult to discriminate whether the bone quality of newly formed bone appears similar to osteoid or cortical bone;therefore, evaluation of bone quality is required. The aims of this study were to measure the bone mineral density (BMD) values of newly formed bone around implants after 4, 8, 16, 24 and 48 weeks, to represent these values on three-dimensional color mapping (3Dmap), and to evaluate the change in bone quality associated with newly formed bone around implants.
The animal experimental protocol of this study was approved by the Ethics Committee for Animal Experiments of our University. This experiment used 20 surface treatment implants (Ti-6Al-4V alloy:3.1 mm in diameter and 30.0 mm in length) by grit-blasting. They were embedded into surgically created flaws in femurs of 20 New Zealand white rabbits (16 weeks old, male). The rabbits were sacrificed with an ear intravenous overdose of pentobarbital sodium under general anesthesia each period, and the femurs were resected.
We measured BMD of newly formed bone around implants and cortical bone using Micro-CT, and the BMD distribution map of 3Dmap (TRI/3D Bon BMD, Ratoc System Engineering). The BMD of cortical bone was 1,026.3±44.3 mg/cm3 at 4 weeks, 1,023.8±40.9 mg/cm3 at 8 weeks, 1,048.2±45.6 mg/cm3 at 16 weeks, 1,067.2±60.2 mg/cm3 at 24 weeks, and 1,069.3±50.7mg/cm3 at 48 weeks after implantation, showing a non-significant increase each period. The BMD of newly formed bone around implants was 296.8±25.6 mg/cm3 at 4 weeks, 525.0±72.4 mg/cm3 at 8 weeks, 691.2±26.0 mg/cm3 at 16 weeks, 776.9±27.7 mg/cm3 at 24 weeks, and 845.2±23.1 mg/cm3 at 48 weeks after implantation, showing a significant increase after each period. It was revealed that the color scale of newly formed bone was Low level at 4 weeks, and then it chronologically changed from Low level to Medium level, and Medium level to High level in the BMD distribution map.
The bone quality was clarified in the newly formed bone in the implant surroundings from BMD and BMD distribution map, and was lower than that of cortical bone.
The chemical composition and stability of hydroxyapatite (HA) film coated on pure titanium screw implants and plates by a sputtering technique were investigated by chemical and physical analyses. The surfaces of the titanium screw implants and plates were sandblasted to an average roughness Ra 2.69±1.1 μm using sintered fluoroapatite particles. The sputtering conditions were 100～500 W and 0.2～2 Pa of argon gas pressure using a radio frequency magnetron sputtering instrument. The HA film thickness was determined as 1.48±0.21 μm by energy dispersive X-ray fluorescence spectrometer (EDX) measurement. The crystal structure and composition were identified as crystalline HA by an inductively coupled plasma-optical emission spectrometer, X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR).
The stability of crystal structure, chemical composition, thickness, surface structure and pH values in ultra-pure water of the HA film were investigated by a long-term stability test for 24 months under 25℃ ± 2℃and 60%±5%RH, and an accelerated stability test for 6 months under 40℃±2℃ and 75±5%RH using XRD, FTIR, ICP, EDX, SEM and pH meter.
No change was observed in crystal structure, chemical composition,and properties of the HA film by these stability tests.
In recent years, zirconia copings produced by CAD/CAM have been used as the superstructures of implants. Since it is considered that the accuracy of fit of superstructures influences the long-term prognosis, it is necessary to maximize this accuracy of copings. Therefore, we produced zirconia copings from three types of working model which were made by clinically applicable methods, and investigated the accuracy of fit of the marginal area in order to compare the precision of the models.
We used a master model in which a lab analogue of seven Straumann implants was established. After taking an impression of the master model, three types of working model were produced. Each working model was produced according to each conventional method, in which a dowel pin model was produced using die casts, a straw model was produced by pouring dental plaster twice using straws, and a Zeiser model was produced using the Zeiser system. Thereafter, zirconia full-bridge copings were produced using CAD/CAM, and, after inserting them into the master model, the marginal discrepancy was measured. Furthermore, the marginal discrepancy was measured in the same way when scanning the master model.
The mean marginal discrepancy was 62 μm in the master model, 164 μm in the dowel pin model, 106 μm in the straw model, and 105 μm in the Zeiser model. The discrepancy was significantly higher in the dowel pin than in the other models. Furthermore, the discrepancy was lower in the master model than in the other models.
It was considered that the expansion of plaster most strongly influenced the dowel pin model. In the other two models in which the expansion of plaster was controlled, dimensional changes were suppressed. Since there were no differences between the straw and Zeiser models, it was revealed that the model production method using straws was simple, accurate, and clinically suitable. However, since differences were found between the master model and the three models produced in the present study, it was suggested that some technical measures to achieve a passive fit is necessary in clinical cases.
We often witness pain without pathological change in the dental office. If patients have such pain, their quality of life deteriorates. We encountered a patient who suffered from intractable atypical odontalgia. The patient was a 56-year-old woman, with the main complaint of mobility of dental implants. We removed the compromised dental implant and placed dental implants again. The pain appeared in the site of the dental implants when she occluded. The patient requested that the dental implants be removed because her pain had continued for a long time, so we removed the dental implants again and the pain was temporarily relieved. However, the pain then began to spread to other teeth and other sites of the mandible, and worsened in spite of surgical treatment. Since we suspected it was neuropathic or psychogenic pain, we treat it by administering intravenous lidocaine, stellate ganglion block and peroral tricyclic antidepressant. The pain improved, but the patient requested tooth extraction because she believed that the pain was odontogenic. The pain increased again after dental treatment or tooth extraction by another clinician. From her clinical characteristics, we considered that an appropriate diagnosis was atypical odontalgia. The mechanisms of atypical odontalgia are far from clear, and its treatment is often difficult. We conclude that it is necessary to cooperate with each clinician in different clinical sections to treat cases of atypical odontalgia.
As the use of dental implants has become widespread, they have been used for elderly patients and patients with serious systemic complications in recent years. We consider that measures are needed to deal with dental emergency situations in private dental clinics. In an ordinary dental clinic, more paradental staff such as hygienists and dental assistants are on duty than dentists. If paradental staff were given training on basic life support (BLS), they would become an effective asset to the clinic in an emergency. Therefore, we held a short course on BLS based on the latest international guideline considering the arrangement of dental equipment, devices and the composition of personnel at the Osaka Implant Center. The course was composed of lectures and practice, and we conducted a questionnaire survey on the change of understanding of BLS procedures among paradental staff. They were answered the questionnaire both before and after BLS practice, and we compared the results of the two questionnaires. The answers to the pre-practice questionnaire showed that almost all of the paradental staff were sufficiently aware of the need for BLS for dentistry, but only 18.8% had a proper understanding of BLS procedures. In contrast, answers to the post-practice questionnaire indicated that BLS understanding had improved in 26 (81.2%). Regarding learning the BLS procedures, it was thought that deciding each role beforehand had reduced confusion and made the subject easier to understand. Fatal situations of the patient are rarely encountered, especially in private dental clinics. In order for the patient to survive the super-acute term which may be a rare experience, continuous efforts to acquire BLS skills and knowledge are needed, and when an emergency occurs, initial action as a team without confusion is indispensable. Although further consideration is needed, a short course on BLS for paradental staffin dental emergency situations would be useful.
The number of elderly people requiring implant therapy is expected to increase. This study aimed to evaluate the clinical performance of implant treatment in elderly patients. Clinical investigations of 25 patients, who were 70 years old or older when they underwent implant surgery, from January 2003 to February 2008 at the Department of Dentistry and Oral Surgery, Niigata Central Hospital, were performed. The following results were obtained:
1. There were 16 females and nine males. Six patients were aged 80 years or older, and the oldest patient was an 86-year-old female.
2. With regard to systemic medical conditions, 13 patients suffered from hypertension;seven patients, cerebral infarction;six patients, hyperlipidemia;four patients, diabetes;two patients, osteoporosis;and two patients, gastric cancer (post-operation state). Among these patients, five patients received anticoagulant therapy for the treatment of cerebral infarction and other conditions.
3. A total of 72 implants were placed in 25 patients. Nine implants were placed in the anterior maxilla, 18 in the posterior maxilla, 28 in the anterior mandible and 17 in the posterior mandible.
4. Two women underwent three operations, and the others underwent one operation. Intravenous sedation was administered to five patients (six times). With regard to complications observed during surgery, excessive elevation of blood pressure occurred in two patients and arrhythmia occurred in one patient. However, these complications did not lead to any further deterioration in the patientʼs condition.
5. A total of 36 prosthetic devices were delivered to the 25 patients. Among these, there were 14 fixed partial dentures, 11 implant-retained mandibular overdentures, and five single crowns. Furthermore, there were six implant-supported partial overdentures (five mandibular partial dentures and one maxillary partial denture).
6. Only one implant was lost before loading during the follow-up period (average, 27.2 months). The cumulative survival rate was 98.6%.
These results suggested that implant therapy is a predictable and safe therapeutic intervention for elderly people.