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D656 Lab Session

D656 Lab Session. October 13, 2008. Arch Length Analysis. Principles of Space Analysis. Space Available vs. Space Required Space Available: mesial to permanent 1 st molar to mesial of contralateral permanent 1 st molar Space Required: Mesiodistal width of all teeth Assumptions:

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D656 Lab Session

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  1. D656 Lab Session October 13, 2008

  2. Arch Length Analysis

  3. Principles of Space Analysis • Space Available vs. Space Required • Space Available: mesial to permanent 1st molar to mesial of contralateral permanent 1st molar • Space Required: Mesiodistal width of all teeth • Assumptions: • The AP position of the incisors is correct (crowding vs. protrusion) • The space available will not change because of growth (less valid in children with skeletal problems)

  4. Mixed Dentition How do we estimate crowding/spacing for unerupted teeth? • Measurement of teeth on radiographs • Estimation from proportionality tables • Combination of the above

  5. Mixed Dentition: Estimation from proportionality tables • Moyer’s: Measure total width of permanent mandibular incisors, use table to predict width of permanent canines and premolars • Tanaka Johnston: • One half the width of permanent mandibular incisors + 10.5 mm = estimated width of mandibular canines and premolars in one quadrant • One half the width of permanent mandibular incisors + 11.0 mm = estimated width of maxillary canines and premolars in one quadrant

  6. Mixed Dentition • Step 1: • Measure mesial of permanent 1st molar to mesial of permanent 1st molar • Divide into 4 segments • Add together, this is space available

  7. Mixed Dentition • Step 2: • Measure the mesiodistal widths of the incisors (Mx/Md)

  8. Mixed Dentition • Step 3: • Width of lower incisors + 21 = estimated size of mandibular canines and premolars • Width of lower incisors + 22 = estimated size of maxillary canines and premolars

  9. Mixed Dentition • Step 4: • Add incisor width + estimated size of premolars and canines (for either Mx or Md) • This is space required • Compare with space available for arch length discrepancy

  10. Permanent Dentition • Step 1: • Measure mesial of permanent 1st molar to mesial of permanent 1st molar • Divide into 4 segments • Add together, this is space available

  11. Permanent Dentition • Step 2: • Measure mesiodistal width of each tooth • Add together, this is space required • Compare with space available for arch length discrepancy

  12. Cephalometrics

  13. SNARelative AP position of Maxilla Reidel Adult (over 18) 82o 3 Children (8-11) 81o 3

  14. SNBRelative AP position of Mandible Reidel Adult (over 18) 80o 3 Children (8-11) 78o 3

  15. ANBRelation of Max to Mand Reidel Adult (over 18) 2  2 Children (8-11) 3  2

  16. Steiner Analysis: • relates the A-P position of the maxilla and mandible to the cranial base and to each other • SNA:Mean = 82°+ 2 • If > mean: protrusive maxilla • If < mean: retrusive maxilla • SNB:Mean = 80° + 2 • If > mean: protrusive mandible • If < mean: retrusive mandible • ANB:Mean = 2° + 2 • If > mean: Class II tendency • If < mean: Class III tendency

  17. MP to FH: • Downs Analysis • Tangent to gonial angle and Me • Mean = 21.9° + 3.2 (range 17-28°) • High MP: unfavorable hyperdivergent pattern • Low MP: hypodivergent pattern

  18. UFH/TFH: • Na-ANS/Na-Me on SN perp • Normal = 45/47% • Adult/Child • If > mean: decreased LFH, brachyfacial tendency • If < mean: increased LFH, dolichofacial tendency

  19. LAFH/TAFH: • ANS-Me/Na-Me on SN perp • Normal = 54/53% • Adult/Child • If < mean : decreased LFH, brachyfacial tendency • If > mean : increased LFH, dolichofacial tendency

  20. Y Axis: • Downs Analysis • Acute angle by FH: S-Gn • Mean= 59.4°+ 3.8 (range:53- 66°) • Y axis indicates the degree of downward, rearward, or forward position of the chin in relation to the upper face • If > mean = suggests Class II pattern, vertical growth of mandible • If < mean = suggests Class III pattern, horizontal growth of mandible

  21. Upper 1 to FH: • Reidel Analysis • Mean = 110° + 5

  22. Lower 1 to MP: • Steiner and Riedel Analysis • Relates L1 to MP (Go-Gn) • Steiner Mean = 1 ° or 91 ° + 6 • Riedel Adult Mean = 93.09 ° + 6.78 and Child Mean= 93.52 ° + 5.78 • If > mean: proclined L1 • If < mean: retroclined L1

  23. Upper1 to Lower1or Interincisal Angle: • Steiner Analysis and Downs Analysis • Mean= 135 ° + 5

  24. E Line: • Ricketts Analysis • Esthetic plane from nasal tip to pog. soft tissue. • U Lip should be 4mm behind the line • L Lip should be 2mm behind the line (+ 2) • Mean based on 9 yoa • Change: less protrusive by 0 .2mm per year

  25. OSU Orthodontic Screenings

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