| For the maxillary sinus, there are only two implant and restoration solutions which can make use of height shortage of alveolar bone:relocating the maxillary sinus to increase bone mass and implanting to keep away from the maxillary sinus. The technology of relocating the maxillary sinus to increase bone mass includes the technique of sinus in floor lift and Osteotome technique. Sinus lift technique, which was universally accepted in1996, can effectively solve the problem of height shortage of available bone in the maxillary posterior teeth area, but the treatment is more trauma and the cycle of this kind of surgical method is long, the cost of the surgery is expensive and there are high risks and complications. In recent years, both scholars at home and abroad have reported that instead of accepting the technique of sinus floor lift and Osteotome technique, patients whose maxillary posterior teeth were lost and whose maxillary sinus bone mass is inadequate choose to accept tilted implant crown bridge near the maxillary sinus walls and far away from the centerline and the short-term effect is satisfactory. In recent years, tilted implant technique has been more and more widely used, mainly available for cases in which height of available maxillary sinus bone is inadequate and there are some bone tissues near/far from the centerline. Analyzing from the theoretical point of view, we can conclude that there are such advantages in adopting tilted implant in the alveolar ridge as:1) implant longer implants can increase the contact area between the implants and bones and increase the stability of the implants in the initial stage;2) in the edentulous jaw cases, tilted implant can increase the spacing between implants, which can limit length of cantilever of the repaired object and make the weight distribution more reasonable;3) tilted implant avoids complex surgeries, such as sinus lift and surgeries of increasing bone mass.The effect of implant surgery technique of increasing bone mass in case of bone deficiency in maxillary sinus area is conformed, but there are many shortcomings. However, regardless of implant technique in pterygoid lamina and zygomatic area, and tilted implant technique, current reports are all about implant in cases of several teeth loss, and the reports about single tooth implant and restoration are never seen before.Currently, there is little evidence on structural form of maxillary sinus palatal bone plate in the maxillary back teeth area of Han population in China. The purpose of this study is to find an implant and restoration technique with little surgical trauma, short treatment cycle and low cost, and which at the same time is suitable for the bone deficiency in maxillary sinus area with single tooth loss, i.e. minimally invasive implant in the maxillary sinus palatal bone plate area. To carry out the technique should be based on knowing the maxillary sinus palatal bone plate structural form in the maxillary back teeth area of Han population. Based on this, the study aims to get the proportion of containable implants with a standard diameter of3.5mm-4.5mm in the maxillary sinus palatal bone plate of Han population and the angle of inclination after the simulative implant. Part I:Research on the Anatomical Shape of Maxillary Sinus Palatal Side Based on CBCTObjectives:1. To analyze and study the anatomical shape difference and its change rules of maxillary sinus in adult Han population through CBCT imaging data.2. To analyze and study the suitable proportion of standard implants in the maxillary sinus palatal side and angle of inclination after the implant (the angle between implant and long axis) in adult Han population through the CBCT slice imaging data.Methods:1. Before scanning the maxillofacial region in the process of conducting head cone-beam CT, to request the patient who is accepted by the hospital and plans to accept the CBCT examination in Guangdong Provincial Stomatological Hospital to fill out a questionnaire under the conditions that they know the fact and approve it. The content includes:patient demographics, general health status, oral hygiene, oral health status, personal habits, and their social and mental status and so on.2. To screen the acquired case data, then collect the cases whose data is complete and in line with the inclusion criteria and perform the imaging data analysis.3. To set the baseline, perform imaging analysis, observe the thicknesses of palatal bone and angle of implant which virtually exists in the position of palatal bone plate of the maxillary first and second molar.4. Statistical analysis was performed using SPSS16.0software for windows.The Independent-Samples Test was used between maxillary first molar group and maxillary second molar group,Levene’test for equality of variances,Satterthwaite test was used when equal variances not assumed,P<0.05was considered statistical significant. One-Way ANOVA was used among four groups,which were maxillary first molar not lost group,maxillary first molar lost group,maxillary second molar not lost group and maxillary second molar lost group. Least-significant Difference test was used between two groups.Welch test was used when equal variances not assumed,and DunnettT3test was used between two groups,P<0.05was considered statistical significant.ResultsFrom February2011to December2011valid questionnaires and corresponding Dicom data were collected from the special clinic center of Guangdong Provincial Stomatological Hospital. In422maxillary sinuses, there were177maxillary first molars and146maxillary second molars lost. The palatal bone plate thickness is greater than or equal to4.5mm in275maxillary first moalr sites and237maxillary second molar sites.In maxillary first moalr not lost sites,the minimum PBT value is0.5mm and the maximum PBT value is16.5mm,In maxillary first moalr lost sites,the minimum PBT value is0.9mm and the maximum PBT value is16.8mm.In422maxillary sinuses,276maxillary second molars and146maxillary first moalrs were lost. In maxillary second molar not lost sites, the minimum PBT value is0.5mm and the maximum PBT value is19.1mm. In maxillary second molar lost sites, the minimum PBT value is0.6mm and the maximum PBT value is13.9mm. In422maxillary sinuses, the minimum PBA value is18.1°nd the maximum PBA value is45°in maxillary first moalr not lost sites when the PBT value is greater than or equal to4.5mm.And in maxillary first moalr lost sites, the minimum PBA value is6.2°nd the maximum PBA value is63.4°. In422maxillary sinuses, whether the PBT value is greater than or equal to4.5mm or not, the minimum PBA value is8.8°nd the maximum PBA value is65.5°in maxillary irst moalr not lost sites,and in maxillary first moalr lost sites, the minimum PBA value is6.2°nd the maximum PBA value is69.3°, the minimum PBA value is10.1°nd the maximum PBA value is79°n maxillary second moalr not lost sites, and in maxillary second moalr lost sites, the minimum PBA value is10.7°nd the maximum PBA value is62.2°.Conclusion1. Through CBCT, clear anatomical shapes of anterior and posterior bone walls of maxillary sinus can be acquired.2. Among the422maxillary sinuses, maxillary sinuses of palatal bone plate minimum thickness above4.5mm in the position of first molar account for65.2%and that in the position of second molar accounts for56.2%. The minimum thickness of palatal bone plate in the position of maxillary sinus first molar is thicker than the minimum thickness in the position of second molar. The difference is of great significance, but whether the molar is lost or not does not affect the thickness.3. Of the422maxillary sinuses, angle of inclination of palatal bone plate in the position of first molar is larger than that in the position of second molar, which has nothing to do with the thickness. The difference is of statistics significance.4. In case where the minimum thickness of palatal bone plate is above4.5mm, the minimum angle of inclination of palatal bone plate in the position of maxillary first molar is6.2°, and the maximum is69.3°. In the position of the second molar, the minimum is10.1°, and the maximum is79.0°. Palatal bone plates with angle of inclination lower than30°in the position of the first molar accounts for42.7%and that in the position of the second molar accounts for58.4%.5. This study shows that if the angle of inclination is controlled at30°, it will be suitable for single tooth palatal side inclined tilted implant across the alveolar ridge crest in the maxillary back teeth area and the implant proportion is the position of the first molar is27.8%, and in the position of the second molar it is32.8%.Part Ⅱ:Clinical Study on Single Tooth Palatal Side Inclined Tilted Implant Across the Alveolar Ridge CrestObjectives:To verify the clinical effect of adopting single tooth palatal side inclined tilted implant across the alveolar ridge crest in cases where the maxillary molar tooth is lost or cannot be retained, height of available bone in the maxillary sinus is seriously inadequate and the minimum width of palatal bone plate is above4.5mm.Methods:1. To clinically collect cases where the maxillary molar tooth is lost or cannot be retained, height of available bone in the maxillary sinus is seriously inadequate and the minimum width of palatal bone plate is above4.5mm from Guangdong Provincial Stomatological Hospital.2. To tell the patients their rights to know; rights of agreement and rights to choose the treatment plans, i.e. the technique of sinus floor lift, Osteotome technique and palatal side inclined tilted implant across the alveolar ridge crest, and their risks.3. All patients were examined by CBCT before surgery. Implant surgeries require to be operated by the same implanting expert with rich experience. CBCT pictures should be taken right after the surgery. The repair time of implant is within three months after the surgery. All surgeries should adopt metal porcelain single crown and bonded retainer.4. To regularly inform the patients for further treatment after the repair is finished.Results: From January2003to January2011, a total number of216cases were collected and a total number of221implants were implanted. Among them, there were32ITI,54Ankylos, and135Bicon. There were137maxillary first molars,84maxillary second molars,93implants immediately implanted in the palatal root. All the patients were accepted follow-up examinations for at least six months after the repair. Among all the cases, one implant failed before the repair, first molars of both sides lost in one case and in the case, after the surgery of tilted implanting two BICON across the alveolar ridge crest, maxillary sinus mucosa of the right side ruptured and caused chronic maxillary sinusitis.Conclusion:1. It is available for clinical treatment to adopt palatal side inclined tilted implant across the alveolar ridge crest and single crown restoration in cases with shortage of bone mass in the maxillary posterior teeth area if the bone mass of palatal is enough.2. In palatal side inclined tilted implant across the alveolar ridge crest, to adopt bone level implants, like tissue level implant has more advantages.3. CT examination is necessary before the surgery of palatal side inclined tilted implant across the alveolar ridge crest.4. Bone mass of at least4.5mm in the palatal side is required for the surgery of palatal side inclined tilted implant across the alveolar ridge crest.5. In the surgery of palatal side inclined tilted implant across the alveolar ridge crest, implants should be immediately implanted in maxillary posterior teeth area and be positioned at the root of palatal side.6. In the surgery of palatal side inclined tilted implant across the alveolar ridge crest, the operator is required to have very rich clinical experience in order to position accurately, or he can use surgical template. 7. Biomechanical risks and long-term effects of palatal side inclined tilted implant across the alveolar ridge crest need further study. |
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