| ObjectiveTo investigate the interproximal interfaces(IPI)of the individual normal occlusion.Specifically,the area,position and shape of IPI were studied to provide guidelines for interproximal enamel reduction and proximal restoration.MethodsThe subjects were individual normal occlusion of 40 adults.Study models of interproximal regions from incisors to first molars were obtained through teeth separation and silicone rubber impressions.Standardized images of proximal walls were captured from the impressions,using the Canon digital camera connected to a stereomicroscope.The images were then managed and analyzed as follows:1.Using the Image J software to trace out the outlines of the IPI and the entire proximal walls,after that,the area were calculated according to pixels.Make the statistical description about the area and position of IPI.Conducted correlation analyses about area and position of IPI and proximal walls' size.2.A series of TPS softwares were utilize to vectoriza contour shape of IPI,all samples were then carried out grometry superimposition to get mean shape of different teeth.Results1.For both male and female,the area of IPI were gradually increasing from maxilla or mandible incisor to first molars.(1)For maxilla of male,The area of IPI from incisors to first molars were1.41±0.17mm2,1.33±0.45mm2,2.80±0.23mm2,2.79±0.54mm2,3.70±0.72mm2,5.51±0.58 m m2in order.There's significant difference between each two teeth in intra-jaw except :IPI between mesial and distal of central incisors(1.41±0.17mm2 and 1.33±0.45mm2respectively),IPI between mesial and distal of canines(2.80±0.23mm2 and 2.79±0.54mm2respectively)of maxilla(P<0.05).For mandible of male,The area of IPI from incisors to first molars were 1.73±0.30mm2,2.51±0.42mm2,3.58±0.54mm2,3.87±0.54mm2,5.75±0.87mm2 in order.There is significant difference between each two teeth in intra-jaw except IPI between mesial and distal of first premolars(3.58±0.54mm2and3.87±0.54mm2respectively)of mandible(P<0.05).(2)For maxilla of female,the area of IPI from incisors to first molars were1.71±0.41mm2,1.79±0.55mm2,2.47±0.47mm2,3.58±0.78mm2,4.26±0.92mm2,5.54±1.35 m m2in order.There's significant difference between each two teeth in intra-jaw except:IPI between mesial and distal of central incisors(1.71±0.41mm2 and 1.78±0.55mm2respectively),IPI between mesial and distal of lateral incisors(1.79±0.55mm2and2.47±0.47mm2respectively)of maxilla(P<0.05).For mandible of female,the area of IPI from incisors to first molars were 1.88±0.33mm2,2.01±0.28mm2,2.81±0.41mm2,3.78±0.52mm2,4.31±0.59mm2 in order.There's significant difference between each two teeth in intra-jaw except IPI between mesial and distal of lateral incisors(1.88±0.33mm2 and 2.01±0.28mm2respectively)of mandible(P<0.05).2.Differences of IPI area between inter-jaw for male were following:the IPI between mandible incisors(1.73±0.30mm2)were significantly larger than which between maxilla(1.41 ± 0.17mm2).IPI between maxilla lateral incisors and canines(2.80 ± 0.23mm2)were significantly larger than which between mandible(2.51 ± 0.42mm2).IPI between mandible canines and first premolars(3.58±0.54mm2)were larger than which between maxilla(2.79 ± 0.54mm2),P<0.05.Differences of IPI area between inter-jaw for female were:IPI area between maxilla lateral incisors and canines(2.47 ± 0.47mm2)were significantly larger than which between mandible(2.01 ± 0.28mm2).IPI area between maxilla canines and first premolars(3.58±0.78mm2)were significantly larger than which between mandible(2.81 ± 0.41mm2).IPI between maxilla second premolars and firstmolars(5.54±1.35mm2)were significantly larger than which between mandible(4.31±0.59mm2),P<0.05.3.There's significant difference between male and female for these couples:area of IPI between maxilla central incisors(1.71 ± 0.41mm2 and 1.41 ± 0.17mm2)and canines-first premolars(3.58±0.77m2 and 2.79±0.54mm2)of female were larger than male,while IPI between maxilla lateral incisors and canines of female(2.47±0.47mm2)were smaller,;IPI between mandible lateral incisors-canines(2.51±0.42mm2 and 2.02±0.28mm2),canines-first premolars(3.58 ± 0.54mm2 and 2.81 ± 0.41mm2),second premolars-first molars(5.75±0.87mm2 and 4.31±0.59mm2)of male were larger than female,P<0.05.4.The area of each quadrant of IPI of maxilla anterior teeth and mandible canines were lingual-gingival(LG),buccal-gingival(BG),lingual-occlusal(LO),buccal-occlusal(BO)in order,of mandible incisors were BO,LO,BG,LG in order(except distal of lateral incisors were BG,LG,BO,LO),of maxilla molars were BO,BG,LO,LG in order,of mandible molars were BO,LO,BG,LG in order.Distal IPI took up a larger percentage of interproximal wall than mesial from lateral incisor to second premolar.5.Consequence of Pearson correlation analysis were as following:For anterior teeth,area of IPI had positive correlation with area of LG,BG,while had no correlatetion with proximal walls.For posterior teeth,area of IPI had positive correlation with area of BO,LO and proximal walls.6.The mean shape of IPI was perpendicular oval for anterior teeth and horizontal oval or reniform for posterior teeth.The IPI's mean shape of mandible premolars was approximate roundness and its long axis was much more away from horizontal plane than maxilla premolars.The IPI's mean shape of maxilla molars was reniform,which was oval of mandible molar and its long axis was closer to horizontal plane.ConclusionQuantitative research on the IPI may depend on teeth separation and precise impression of interproximal walls.The conclusions were following:1.Area of IPI were gradually increasing from maxilla or mandible incisors to first molars for both male and female.2.The position of IPI of anterior teeth mostly located in gingival and lingual,except mandible incisors,which mostly located in occlusal and in center of LG.IPI of posterior teeth mostly located in BO,BG and LO.3.The mean shape of same teeth between maxilla and mandible was similar,which was occlusal-gingival oval for anterior teeth,while was buccal-lingual reniform and oval,respectly for maxilla and mandible premolars and first molars. |
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