Developmental Characteristics Of Maxillary Tuberosity At Different Ages

Maxillary tuberosity (MT) area is an important region of the maxilla downdevelopment of backward extension. It bounded mesially by the last eruptedmolar and maxillary sinus, and distally by the pterygopalatine fissure andpyramidal process of the palatine bone. As children grow oder, the Maxillarytuberosity interfaces anteriorly the first permanent molarand at20years thethird molar, suggesting that the Maxillary tuberosity skeletal growth is affectedby dental dictation. At the same time, MT growth is regulated by sutural growth,periosteal growth and the maxillary sinus pneumatisation. But, Maxillarytuberosity bone growth, especially in the different age stages, and infuluence tothe maxilla, have not been reported. Growth cycle, growth rate and amount ofthe maxillary tuberosity are worthy of further study.In this study we use panoramic radiographs to observe the bone growth andthe growth characteristics of the maxillary tuberosity in different periods, and to provide a reference to the feasibility and timing of molar distalization inorthodontic treatment. The study includes two partes:Part1. Measurement and Calibration of the magnification of panoramicradiographs in after tooth segmentMaterial and Method: To select10cases that third molar erupted randomlyfrom the overall sample184cases. In selected cases, useing wax to cement5mm diameter stainless steel beads on the maxilla first/second/third molarocclusal surface. And choicing1.1times magnification mode to shoot a fullpanoramic radiographs. Radiology equipment is our hospital radiology singledental X-ray machine. The ball diameter and the actual ball diameter measuredin the panoramic radiographs to calibrate the magnification of the molar area.Results: the results showed that, the first molar region amplification rate is1.14±0.06, the second molar region is1.20±0.03, the third molar region is1.27±0.02. The first molar region magnification is different from the second/thirdmolar region (p <0.05). No significant difference (p>0.05) between the secondmolar region and third molar region.part2. The measurement analysis of bone growth and developmentcharacteristics of maxillary tuberosity area in different agesMaterial and Method: To select the cases of the Orthodontics,2009~2011period184cases,80cases of male and female104cases. Experimental sampledivided by age group,8-9years old,10-11years,12-13years,14-15years,16-17years,18-20years, six age groups. And determine the subjects of theinclusion criteria:①the selected samples are bone facial type1②the first molarrelationship is Class I, no dislocation and reverse③the second molardevelopment, no dislocation and reverse④maxillary bone development symmetry, no deflection. The patients included in the experiment to be shootpanoramic radiograph under the1.1times magnification mode. And the measureof the experiments formulated in panoramic radiograph, then to analyze.Results:the results showed that,①in the vertical direction, the growth of themaxillary tuberosity during the ages8-20in the first, second, third molars were5.04mm,18.46mm,21.15mm in male; and6.95mm,21.55mm,17.22mm in female;②in the horizontal direction, the horizontal distance of the first, second and thirdmolars in the nasal floor flat on the pedal to the cheekbones maxillary ridge, were5.38mm,4.84mm,0.99mm in male; and5.40mm,3.95mm,1.99mm in female; thehighest point of the trailing edge of the maxillary tuberosity and the posteriormargin of bump into the the cheekbones maxillary ridge distance increase were:4.87mm,5.21mm in male;and3.97mm,2.91mm in female.Conclusion:Growth and development of the maxillary tuberosity do not increase stablywith age, but there are significant peak period to provide the desired position ofthe maxillary second molar eruption in children10-11years of age, and thenentered arelatively stable period, the other fast-growing to14-15years of age.In clinical orthodontics, it is necessary to effectively grasp the golden period ofdevelopment of the maxillary tuberosity, that is, children10-11years, especiallybefore the eruption of the maxillary second molar. At this stage, pushingmolars distalization movement can be effective in preventing the second molarimpacted or ectopic.