There are two methods of evaluating the cell compatibility of metal implant materials using cultured cells: the direct contact method, and the extraction method. In the former, a material is brought into contact with cells directly in a medium, while extract of a material is liberated on the cells in the latter method.
This study was conducted employing the two methods, using globular titanium powder, mouse fibroblast-derived L929 cells, and artificial saliva solution with titanium after anodic polarization in the solution. The results for the adhesion of cells and the cell proliferation characteristics were compared. The results using the direct method showed adhesion of the cells to the globular titanium powder, and the cells grew vigorously three to nine days after the adhesion. Also, adhesion of the cells to the artificial saliva solution was observed, and the cell proliferation after the adhesion was almost the same. The ion elution in this case was measured as 0.8 ppm by inductively coupled plasma mass spectrometry (ICPS).
Using nickel standard solution, which is a positive reference material cell, adhesion and proliferation of cells were not observed.
These results suggest that globular titanium material is suitable for biomaterial because cells adhered to it from the beginning and proliferated.
The effects of titanium surface conditions on bone-related gene expression profile in osteogenic cell culture are not fully understood. We previously reported that the expression of bone-related genes in osteoblastic cells was upregulated when cultured on titanium compared with polystyrene. However, the upregulation ranged only up to 2 times and did not seem to fully explain the biological phenomenon of osseointegration. Osteoblastic culture studies normally utilize dexamethasone in the media to induce the cells into osteoblastic lineage. We hypothesized that culturing the cells under the dexamethasone-free osteoinductive condition may increase the contrast of the effect of titanium and its surface roughness on the degree of osteoblastic differentiation. Objectives: The objective of this study was to examine the bone-related gene expression profile of bone marrow stromal cells cultured on titanium under the dexamethasone-free osteoinductive condition.
Methods: Rat bone marrow stromal cells were cultured on either polystyrene surface, machined titanium or acid-etched titanium without dexamethasone. The differentiation of the cells was evaluated by the expression of the representative bone marker genes using reverse transcriptase-polymerase chain reaction (RTPCR) at days 7, 14 and 28 of culture. Results: Osteopontin gene expression was consistently upregulated up to 3.5 times on both the titanium surfaces compared to the polystyrene, while osteocalcin was upregulated particularly on the acid-etched surface up to 38.8 times at the initial stage of day 7. The sustained gene expression at day 28 on the titanium cultures was seen for all of the genes tested (collagen I, bone sialoprotein II, osteopontin, osteocalcin). Conclusion: The positive modulation of bone-related gene expression by the presence of titanium was detected in the dexamethasone-free osteoinductive media compared to the previously reported results using the dexamethasone-containing osteoinductive media. The results suggest that these culture conditions are beneficial for bone-related gene expression profile studies.
Implant placement into the extraction socket immediately after extraction has been attempted. It is important to determine the condition of the bone surrounding the implants, using X-ray images and mobility measurements. In the present study, we determined the mobility of implants which were placed into extraction sockets immediately after extraction,and observed the changes of bone tissue surrounding the implants over time and investigated the relation among three categories. Furthermore, we examined whether such findings could be used to specify the time of osseointegration and of superstructure set.
Implants were placed into extraction sockets immediately after extraction of upper lateral incisors for experimental animals and mobility was measured over time starting just after implant placement. In addition, the tissues surrounding the implants were observed using bone-microvascular corrosion cast specimens and bone volume was analyzed using soft X-ray images.
Implant mobility was decreased just after implant placement to 2 weeks, and then increased to 4 weeks and was stable to 12 weeks after implant placement.Bone formation was partly observed surrounding implants from 2 weeks after placement, and bone formation became vigorous at 4 weeks after placement. In addition, bone volume was increased at 4 weeks after implant placement.
From these findings, we considered that the mobility of implants placed immediately after extraction corresponded to postoperative changes of the bone tissue surrounding the implants. Accordingly, we concluded that the time of osseointegration could be determined on the basis of mobility measurements, and that such measurements are useful for determining the time of superstructure set.
Purpose: Oral implant therapy is very useful for the reconstruction of occlusal function. Especially, sinus lift is an important and standard surgical procedure for proper implant installation in cases of insufficient vertical ridge bone dimension, such in posterior edentulous maxilla. The aim of this study was to investigate the change of grafted bone tissue surrounding placed implants in frontal sinuses of adult dogs.
Materials and Methods: Four adult male dogs were used for this experiment. Autogenous bone blocks from the iliac crest were used as grafting materials, and then filled in 8 sides of the frontal sinuses in 4 dogs. Implants were placed immediately or four weeks after bone grafting.
The selected observation periods were 2, 4, 8, and 12 weeks after installation, whereupon the animals were sacrificed. The animals were divided into immediate installation models and delayed installation models,and we conducted a serial comparative study. All surgical procedures were carried out by the same surgeon.
Results: New bone formation was observed in the border between basal bone and grafted bone under the sinus membrane at 2 weeks after bone grafting. Serial grafted bone volumes were gradually reduced in the sinuses. The amounts of bone resorption surrounding placed implants in immediate installation models were greater than those in delayed installation models.
Early after sinus lift, tissue atrophy was observed in the sinus membranes and goblet cells ware lacking, however, the membranes gradually recovered until 8 weeks.
Conclusion: The results indicated that delayed installation yielded greater implant stability than immediate installation. The sinus membrane atrophied due to the surgical stimulation until 4 weeks, but gradually recovered in histological observation.
A limited cone-beam X-ray CT, known as Ortho-CT, was developed based on multi-functional panoramic apparatus and was improved as a "3DX multi-image micro CT (3DX)" for practical use. Recently, a new type of 3DX (3DX-FPD) having a flat panel detector instead of an image intensifier has been released. 3DX-FPD adopts two kinds of columnar radiation field, 40×40 mm (diameter×height) and 60×60 mm. Some investigations of the limited cone-beam CT apparatus including 3DX demonstrated high spatial resolution, however, different values were measured in a few surveys on dosimetry of 3DX. In addition, there has been no report on the dose of 3DX-FPD. Therefore, this study set out to estimate the dose difference among 3DX-FPD and other conventional radiographies (dental radiography, panoramic radiography and computed radiography (CT) and between two radiation fields in 3DX-FPD. Dosimetry of the organs and the tissues was performed using an anthropomorphic Alderson Rando phantom and a thermoluminescence dosimeter.
The results are summarized as follows:
1. The dose of 3DX-FPD was less than 7/10 of that of CT, however, it was more than 10 times that of dental radiography or several times that of panoramic radiography, respectively.
2. The absorbed dose in a field of 60×60 mm for the contralateral mandibular molar, eye, parotid gland and skin regions was almost 2 times higher than that in 40×40 mm with 3DX-FPD.
Surface wettability of implants and functional groups created on implant surfaces play important roles in the initial adhesion and subsequent behavior of cells. This study aimed to clarify the effect of glow-discharge plasma treatment and storage condition on surface wettability (contact angle) of titanium. In addition, functional groups created on titanium surfaces were identified. The water contact angle dramatically decreased after glow-discharge plasma treatment with less than 5 degrees, leading to hydrophilicity. This value rapidly increased over time in air atmosphere, and reached 72 degrees at 7 days. On the other hand, the hydrophilicity was maintained by storage in distilled water or acetone with contact angles of 43 degrees or 14 degrees at 7 days, and 54 degrees or 29 degrees at 30 days, respectively. X-ray photoelectron spectroscopy revealed that basic hydroxyl groups were introduced on the titanium surfaces by immersion in distilled water after glow-discharge plasma treatment, suggesting that this process promotes osseointegration of titanium implants. In conclusion, glow-discharge plasma treatment and subsequent storage in water or acetone is a promising method for controlling the surface wettability and introduction of functional groups.
A 70-year-old female who has metal allergy against palladium and chromium wished to receive implant-supported restoration for her partial edentulous portion. It is well known that cross-allergic reaction against numerous kinds of metals can be seen in some metal allergy patients, so it was necessary to confirm whether titanium could be used for this patient. In order to perform the implant therapy safely, we did an exposure test with intra-oral titanium restoration in addition to a patch test to identify whether she had allergy to titanium. The result of the patch test was negative for titanium. After the trial exposure period of 6 months, she showed no signs and symptoms of titanium allergy. Finally, we diagnosed that there was a low clinical risk of using titanium in this patient, and so planned a bone-anchored fixed partial denture with titanium frame and hybrid ceramics. First, titanium implants were placed in her partial edentulous portion. After a healing period, the secondary operation (abutment connection) was conducted, and the implant-supported fixed prostheses were fabricated to recover her masticatory function, speech function and esthetics. The treatment outcome of this patient was evaluated with a self-administered questionnaire. The results of assessments suggested that the implant-supported restoration improved the patient's masticatory function, speech function, esthetics and quality of life.
A case of masticatory functional recovery by implant supported overdenture of the mandible pretreated with a plastic operation of tongue flap is reported. The patient was a 71-year-old male who had undergone oropharynx cancer resection and reconstruction with free rectus abdominis muscle flap 7 years earlier. After the operation, the patient had suffered from an oral to chin fistula, so fistula closure with tongue flap had been performed. The patient had then been treated with dentures to improve masticatory function, but the denture had not adapted because of the tongue flap over the anterior alveolar part of the mandible. The patient was referred to our clinic, and was indicated for treatment with implant supported overdenture. At first, a plastic operation of tongue flap was conducted, and good tongue movement and ideal alveolar shape were obtained. After the plastic operation, four implants were placed in the anterior part of the mandible. The patient now wears an implant supported overdenture and has good masticatory function.
Clinical success data for SLA surface implants has been reported, however these data were limited, for example, only for standard sites,or immediate loading situation, or molar sites in mandible and were not applicable to other clinical situations. This study investigated the clinical success data utilizing SLA surface implant involving every clinical situation, such as GBR, immediate loading, early loading, immediate placement, sinus lift, etc.
822 patients (mean age: 49.7 years, range 18-85 years) participated in this prospective study at 7 dental offices, and a total of 1,824 SLA surface implants (Straumann Institute) were placed. The follow-up period covered the time between implant placement on 01/01/2002 and 12/31/2004.
The survival rates and success rates with SLA surface implants were assessed and evaluated.
The results obtained were as follows:
1.Cumulative survival rate and success rate of SLA surface implants were 99.0% and 97.1%, respectively.
These results suggested that Straumann SLA surface implants give good results.
Inflammatory responses resulting from surgical stress following implant placement often involve temperature increases in addition to swelling and pain. To more objectively assess inflammatory reactions, the authors of this report independently developed a high precision system measuring the surface temperature of oral mucosa, and measured temperature differences in affected regions following implant surgery. Seventy cases of implant surgery (114 implants), undertaken by the same surgeon and facility and using the same implantation system (AQB Implant one piece type), were monitored. All patients had a pre-surgical status of 1 or 2 on the ASA Physical Status Classification System and were aged from 28 to 68 years (average age 53.2 years). Oral mucosa surface temperature in the buccal area surrounding the implants was measured for ten days after implantation. The baseline was the temperature of the same region pre-surgery, and analysis of variance (ANOVA) and Dunnettʼs test were used in statistical processing. Statistical analysis confirmed a constant pattern of temperature change. The results showed that the temperature of affected areas rose sharply from pre-surgery temperatures the day following surgery, the greatest difference in temperature being 1.16±0.18℃(mean±SD) and started decreasing two days after surgery. The difference in temperature dropped by half 5.9 days after surgery and returned to near pre-surgery levels ten days after surgery. The greater the number of implants and length of surgery, the higher the temperature in the affected region rose, and the slower the temperature decreased from day to day. In cases where one implant was placed, a significant rise in body temperature was only confirmed in the day following surgery. In cases where 2 to 4 implants were placed, a significant difference was confirmed on the first and second day after surgery. Daily measurement of the temperature of affected areas following implant placement is considered to be worthwhile in post-surgical management and to be a useful method of observing the wound healing process. Additionally, measurement of body temperature is considered necessary for whole body management.