| Recently implants researchers pay more attentions on immediate implant loading. There is a close relationship between implant stability during osseointegration and success of immediate implant loading. But in clinical implant dentists often judge stability subjectively and there are little objective methods. So it is difficult to judge the stability accuracy and to choose the right time for loading. This often leads to the failures of implants. Therefore it is necessary to study deeply. Nowadays researches mainly focus on abroad data collection and domestic case reports. There is no systematic study and analysis about measurement of implant stability and immediate loading. Thus we set the study to compare the implant stability changes during between no loading and immediate loading implant osseointegration. We hope to give experimental evidence for immediate loading.Study objectives:In this study we measure the implant stability of 78 patients (103 implants) after osseointegration with resonance frequency analysis (RFA) (OSSTELL). For 47 patients (79 implants) we measure the no loading implant stability during osseointegration. We conduct the implants immediate loading clinical experiments for 12 patients (25 implants) and measure the implant stability. Through the study we make sure of the extent of second stability and the changes of implant stability with no loading and immediate loading. This can be helpful for the success of implant immediate loading.Methods results:Part I: For 78 patients who had finished implant inserts above 3 months and were able to start prosthetics; analysis was based on the 103 ITI SLA implants that were successfully measured using RFA and panoramic radiographs in order to learn the extent of implant stability after implant osseointegration. The results show that ITI SLA implant stability quotient (ISQ) after osseointegration changed from 58.33 to 85.67, the mean value was 76.29±5.25 and the distribution was almost normal distribution. The ISQ of male patients (76.20±5.20) was higher than the females (75.56±5.70); for different imp lant location, the ISQ of maxillae (75.61±5.05) was lower than the mandible (76.97±5.43). There was no statistically significant difference (P>0.05). Bone quality and bone quantity according to the index proposed by Lekholm and Zarb were registered after surgery. The ISQ of class I and II bone (78.73±3.5) was higher than the ISQ of class III and IV (74.27±5.63). And the difference was statistically significant (P<0.05). Furthermore we studied the ISQ of different type implants (different length and diameter) and found no significant difference (P>0.05). So the bone type has the closet relation with the osseointegrated implant stability. Part II: the analysis was based on the 79 implants (47 patients) that were successfully measured using RFA at all postoperative intervals (at implants placement, postoperative 4 weeks, 8 weeks and 12 weeks) for clearing the implant stability changes during no loading osseointegration. The RFA of 79 ITI SLA implants showed a decrease in bone-implant stability in the first 4 weeks from 76.77±4.78 (class I, II),69.02±8.73 (class III, IV) to74.52±4.79 (class I, II),66.93±8.43 (class III, IV); Followed by increases in stability till the 12 weeks (class I, II: 77.42±4.87; class III, IV: 69.71±8.68). During no loading osseointegration the mean value of ISQ is class I, II: 75.86±4.78, class III, IV: 68.33±8.73. The ISQ of bone I, II is higher (P<0.05) and could bear more loading. Furthermore the ISQ is lower at postoperative 4 weeks and dentists need pay more attentions to the implant-bone micro-mobile.Part III: 12 patients whose bone types were class II received 25 implant immediate loading. The ISQ was recorded with RFA at implant placement, after 1, 2, 3, 4, 8 and 12 weeks, and then analyzed statistically. This would show the implant stability changes of immediate loading osseointegration. The results show: The ISQ of ITI SLA implant was 80.33 at implant placement, then at postoperative 1 week: 79.00; 2 weeks: 71.33; 3 weeks: 72.07; 4 weeks: 73.28; 8 weeks: 76.34 and 12 weeks: 79.33. The lowest ISQ was at postoperative 2 weeks. The implant stability should be kept monitoring during osseointegration. In class II bone, the primary stability should be kept ISQ >80; in postoperative 1-3 weeks, the implant stability decreases quickly. During this time the intensity of loading should be adjusted according to the change of implant stability. During whole osseointegration the ISQ should be higher than 70, which is necessary for the immediate loading osseointegration.Conclusions:1. Application of RFA (OSSTELL) is able to provide objective and systemic measurement for implant stability.2. The mean value of implant stability quotient (ISQ) after osseointegration is 76.29±5.25. For osseointegration the ISQ should be at least higher than 60.3. The recipient site of implant has the closest relation with the implant stability.4. The lowest time of stability of no loading implant osseointegration is postoperative 4 weeks and the implant-bone micro-mobile should be control strictly especially during this time.5. For immediate loading, the implant stability should be kept monitoring through the whole osseointegration using RFA (OSSTELL). The lowest stability of implant is at postoperative 2 weeks and the ISQ should be kept higher than 70 in the osseointegration. According to the changes of implant stability the intensity of loading is adjusted in order to make sure obtaining osseointegration.
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