| Background:Since middle 1960s, when Branmark proposed the theory of implant osseointegration, implant restoration has approached to a mature discipline after half a century of validation and practice. Dental implant restoration has currently become the preferred treatment for patients with missing implants. With the development of oral implant restoration technology, the requirements for success rate of dental implant and reduction of planting cycle are also increasing. And good implant osseointegration is a premise for success implant restoration. Traditional theory believes that after bone healing time without interference (6 months for maxillary bone,3 months for mandible bone) good implant restoration can be achieved. With the progress of the related research, scholars have confirmed that implants have good stability, which helps to accelerate the speed of implant osseointegration, form a more solid implant osseointegration interface and shorten load time of the upper structure of the implant. So successful implant osseointegration and stability can help to improve the success rate of implant and shorten the treatment cycle.Implant stability mainly includes two parts-the primary stability and secondary stability. Good primary stability helps the formation of the implant-bone interface, and the secondary stability is a reference index for assessment on implant osseointegration. Insertion torque value (ITV) of implant was mainly used in clinical to assess the primary stability of implant. This value may be a visible reference index in implantation, but due to the invasive trauma, it cannot be used for continuous measurement of the stability of the implant. In this context, Meredith scholars measure the stability of the implant by resonance frequency analysis (RFA) based on resonance theory, so as to assess the implant osseointegration. The method is noninvasive, objective, accurate, sensitive and of dynamic continuous detection. Other scholars did a wide range of related research and found that there was a certain correlation between the implant stability measured by RFA and implant osseointegration. Now, the method has been widely used in dental implant restoration.But due to the diversity of the patient’s bone quality and bone mass, it is often difficult to obtain the so-called "right" ITV during implantation operation, to form good primary stability of implant. Therefore, more and more scholars begin to pay close attention to the relationship between ITV and implant osseointegration.Whether there is any influence of implants with different ITVs on healing time of implant? Whether there is any influence of implants with different ITVs on stability of implant? What’s relation between ISQ values and loaded restoration implants? There is no uniform consensus on these issues in oral implantation academia filed. This experiment aims to evaluate the correlation between ITV and stability of implant with implant osseointegration by RFA, so as to provide an appropriate bone healing time for reference to oral implantation doctors. Purpose:Resonance frequency analyzer was used to observe the influences of different ITVs on implant stability and osseointegration of implant at different time points and in different implant areas.Method:1. Inclusion and exclusion criteria:Inclusive Criteria:(1) older than 18 years old, without obvious systemic diseases; (2) patients missed implants for more than 3 months in area tending to implant; (3) no soft tissue defect in area tending to implant; (4) patients had good compliance, who can guarantee timely and regularly review and signed the informed consent; (5) no cardiac pacemaker; (6) area tending to implant was the chewing function area of posterior; (7) vertical bone mass was greater than 10 mm in mandibular implants and greater than 7 mm in maxillary implants; (8) buccal and lingual bone mass in restoration-missing area, to adapt to the implants of molar area in posterior.Exclusion criteria:(1) patients did not meet the inclusion criteria; (2) poor oral health condition; (3) acute or chronic systemic disease may affect the operation or secondary treatment and re-treatment and other related diseases; (4) patients with cardiac pacemaker. 2.Collection of clinical data: Primary stability of implant was measured and analyzed. According to the above criteria,49 cases of patients admitted in our implantation center from January 2014 to October 2014 were included. Among them,29 cases were male while 20 cases were female, aging from 20 to 75 years. There were a total of 86 implants. 3. Measurement and grouping of implant torqueContraindications were excluded. And the patients signed informed consent. The patients were given conventional antibiotics before operation. A skilled oral implantation dentist did the operation with appropriate implants and surgical procedures based on the actual situation of the patients. Struaman surgical operation manual was strictly abided intraoperatively.1. Experimental data I:the patients were grouped on the basis of different intraoperative implant ITVs:Group A (low ITV,0～15 N·cm),27 implants; Group B (middle ITV,16～35 N·cm),39 implants; Group C (high ITV,36～50 N·cm),20 implants.2. Experimental data II:Low ITV (0～15 N·cm) of posterior area of mandibular implants,10 implants.3. Experimental data III:Low ITV of posterior area of maxillary and mandibular implants (16 maxillary implants and 11 mandibular implants).4. RFA measurementResonance frequency analyzer (Osstel) was used to measure implant stability quotient (ISQ) immediately after completion of implantation, so as to assess the intraoperative primary stability of implants. Struaman SLA-the accessory of Osstel analyzer was installed to the implants. According to the standard measurement of Osstel analyzer, ISQ of each implant was measured in mesio-incisio-distal direction and buccal-lingual direction perpendicular to the measuring rod. Mean value of the record was finally adopted. All collection and records were completed by the same person.5. Data collection1. The implants were healed without interference or load. ISQ was measured by Osstel analyzer on postoperative 8 weeks and 12 weeks.2. Mandibular low ITV group was healed without interference or load, and restored 3 months after operation. One month after wearing the restoration, ISQ was measured by Osstel analyzer.3. ISQ of each case was collected and input into Osstel-matched software for classification and archiving. Patient’s basic information was also established by Excel: patient name, outpatient number, imaging number, admission time, basic situation of operation area, surgical procedures, specification and quantity of the implant, intraoperative ITV, ISQ at 8 week follow-up or 12 week follow-up, ISQ at restoration and wearing the restoration, ISQ after 1 month of wearing the restoration.6. Statistical Analysis1. Experimental data I:When all data were input into the Excel to establish database, normality test was performed in each group. Nonparametric test was used for different time points (normal distribution test was performed at first, if the data was in a non-normal distribution, Kruskal-Wallis test/Mann-Whitney test was used for analysis). Multivariate repeated analysis was performed. SPSS13.0 was used for statistical processing to detect whether there was statistically significant differences.2. Experimental data Ⅱ and experimental data Ⅲ:All the data were input into Excel to establish database. SPSS13.0 was used for statistical processing. Kruskal-Wallis test was used for nonparametric tests.Results:1. Patients’ conditionAll implants were survival. There was no loose condition. No obvious peri-implant bone resorption was seen in imaging examination. And the patients were given implant restoration and obtained satisfactory effects and the implants can perform normal function. In 1 month and half-a-year follow-up, implant restoration had good function and the patients were satisfied with the restoration.2.1 Observation of ISQ values in each group with different time pointsComparison in the group showed that with the time prolonged, ISQs of 3 groups were all on the rise. There were no obvious differences between ISQs at 8 weeks and 12 weeks of each ITV group. ISQ at the 8th week was maximum in low ITV group.Statistical analysis was used. For ISQ at different time points, only ISQ immediately in the operation was statistically significant between 3 groups (P<0.05); For ISQ at the same time point of 3 groups, ISQ immediately in the operation of group A< group B< group C (P<0.05); At 8 weeks postoperatively, ISQ of group A was increased obviously, and there were no statistical differences in ISQ between 3 groups at postoperative 8 weeks and 12 weeks (P>0.05).2.2 Comparison and observation on ISQ of each ITV group and different time pointsStatistical analysis was used. Through comparison on ISQs of different time points in each group, it was found that there were statistical differences between ISQs of different time points including immediately in the operation and postoperative 8 weeks and 12 weeks in low and middle ITV groups (P<0.05). There were no obvious differences between different time points in high ITV group (P>0.05).3. ISQ of mandibular posterior area in low ITV group one month before and one month after restoration and wearing restorationAfter 3 month of healing process, implant of mandibular posterior area in low ITV group had good stability by RFA. And the upper structure of implant was restored. RFA was used to measure ISQ one month after wearing restoration. Kruskal-Wallis test was used for nonparametric test statistics analysis at two time points. It can be seen that mean value of all the observed ISQs was slightly increased after 1 month. And there were no obviously statistical differences between ISQ of two time points.4.Comparison on maxillary and mandibular implant with low ITV at different time pointsThere were statistical differences in ISQ of maxillary implant between intraoperative, postoperative 8 weeks, and postoperative 12 weeks (P<0.05); and ISQ showed an increasing trend; There were statistical differences in ISQ of mandibular implant between intraoperative, and postoperative 8 weeks (P<0.05); and there were no obviously statistical differences between postoperative 8 weeks and postoperative 12 weeks (P>0.05).Conclusions:1. This experiment showed a positive correlation between ITV and ISQ. The larger the ITV was during implantation, the larger the ISQ was.2.8 weeks within implantation was a key period for good implant osseointegration; ITV had no significant effects on osseointegration beyond 8 weeks.3. After 3 months of healing time, mandibular implant with Low TV group can repair the upper structure. Then after a month of weight load, ISQ value did not drop. Implant osseointegration and function were both good. No obvious bone resorption was seen.4. For mandibular implant with Low TV group, ISQ after 8 week of healing was not statistically different with ISQ at 12 weeks.5. RFA was used to assess the stability of maxillary implants with Low TV group. After 12 weeks of healing time, implant stability was increasing. After 8 week and 12 week healing time, implant stability was increasing. It was speculated that implant osseointegration was going on. |
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