| Objective:The aim of this study was to investigate the survival rate and technical complications of the single-molar implant restorations,through reviewing the single-molar cases that had been finished from April 2009 to December 2018 in the implant-ology department,the Affiliated Stomatological Hospital of Kunming Medical University.In addition to risk factors of abutment fracture were analyzed,the relative safety three dimensional position of implant placement were also discussed.Methods:Experiment 1:Through reviewing the single-molar cases that had been finished from April 2009 to December 2018 in the oral implantology department of the Affiliated Stomatological Hospital of Kunming Medical University,662 implants of 639 patients were collected according to certain exclusion criteria,and recorded the rate of survival implants and technical complications.662 abutment were grouped by gender,occlusion habit,jaw position,restoration position,implant type,implant diameter and length,abutment type,crown retention modes and loading time,then statistics the number of fractured abutments for each group.The SPSS23.0 software was used for statistical analysis.The data of each group used the chi-square(?2)test to analysis.When P<0.05,the difference between the groups was statistically signify-ant.Experiment 2:According to certain inclusion and exclusion criteria,40 of 662 implants in experiment 1 was included,the fractured abutment group was 9 implants of 9 patients and the control group was 31 implants of 30 patients.The clinical crown height(mm)?mesiodistal horizontal offset(mm)?mesiodistal inclined angle(°)and buccolingual inclined angle(°)of implants were measured by the periapical radiograph and CBCT.The data of each group used SPSS23.0 statistical software to analysisResults:Experiment 1:1?The implant survival rate was 98.9%in the molar area from April 2009 to December 2018.One of the seven failure implant had been extraction due to biological complication,the others were failure due to technical complications.The rate of technical complications of single-molar implant restorations was 16.0%.The rate of technical complications of screw-retained crowns is as follows:abutment loosening>chipping or fracture of veneering>occlusal screw loosening>abutment fracture>implant fracture.Moreover,in the cement-retained crown,the rate is dece-mentation chipping or fracture of veneering>abutment fracture>abutment loos-ening>implant fracture.2?The statistical results of the abutment fracture relevant factors showed that the fracture rate of males was significantly higher than females(P<0.05).There was a higher fracture rate of patients with bad occlusion habits(P<0.05).The maxillary group was significantly higher than the mandibular group(P<0.05).The fracture rate of the standard implant group of 4.0?4.5mm was significantly higher than the other two groups(P<0.05),and the cement retention was significantly higher than screw retention(P<0.05).There was no significant difference in the groups of restoration position,implant type,implant length,abutment type and loading time(P>0.05).Experiment 2:The clinical crown height of the fracture group implant was 11.30±1.82mm,with a minimum of 7.09 mm and a maximum of 13.30mm.The control group was 10.56 ±1.690mm,and the minimum crown height was 7.25mm,the maximum was 13.13mm.The data of two groups were normally distributed.Two independent samples t-test showed that the difference of the clinical crown height space between the two groups was no statistically significant(P>0.05).The average mesiodistal horizontal offset of the fracture group implant was 1.78±0.92 mm,with a minimum of 0.57 mm and a maximum of 3.55 mm.The control group was 1.12±0.76 mm,and the minimum horizontal offset was 0.10.mm,the maximum was 3.5mm.The data of two groups were normally distributed.Two independent samples t-test showed that the difference of the horizontal offset between the two groups was statistically significant(P<0.05).The minimum and maximum mesiodistal inclined angle of fracture group implants was 1.1°and 23.2°,control group was 1.3° and 15.8°.The minimum and maximum buccolingual inclined angle of fracture group implants was 1.40 and 15.9°,control group was 1.4° and 28.9°.All the data were skewed distributed.Two independent sample Mann-Whitney U tests shown that there were no significant difference between two groups in the mesiodistal and buccolingual inclined angle(P>0.05).Conclusion:1.Through reviewing the single-molar cases that had been finished from April 2009 to December 2018 in the oral implantology department of the Affilia-ted Stomatological Hospital of Kunming Medical University,the survival rate of single-molar implant was 98.9%.The main factors affect implants failure is technical complication.2.The technical complications rate of single-molar implant restorations was 16.0%.and the most common technical complications of screw-retained crowns is abutment loosening,and the most common complications of cement-retained crown is dece-mentation.3.The incidence of abutment fractures in males,patients with bad occlusion habits,maxillary molar areas,standard implants and cement retention abutments is significa-ntly higher.4.The difference of the crown height between the fracture and control groups was no statistically significant.It is not yet possible to increase the risk of abutment fracture when the crown height is 11.30±1.82 mm.5.It is suggested that the mesiodistal horizontal offset of implant displacement is an important factor of abutment fracture.6.When the implant's mesiodistal inclined angle?23.2°,buccolingual inclined angle?28.9°,there is no significant difference between the abutment fracture group and the control group.It still requires further study whether the risk of abutment fracture is increased,When the angles are greater than the above. |
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