Mixed Dentition Analysis PDF

Mixed Dentition Analysis Francisco Plaza DDS MS  Reference  "The clinical application of a tooth-size analysis." – Bolton, Wayne A. American Journal of Orthodontics 48.7 (1962): 504-529.  Essentials For Orthodontic Practice, chapter 13 – Mich...

Mixed Dentition Analysis Francisco Plaza DDS MS  Reference  "The clinical application of a tooth-size analysis." – Bolton, Wayne A. American Journal of Orthodontics 48.7 (1962): 504-529.  Essentials For Orthodontic Practice, chapter 13 – Michael L. Riolo and James K. Avery  Handbook of orthodontics 4th edition, chapter 11 – Robert E. Moyers  Tooth Size Arch Length (Perimeter) Analysis  Dental Arch dimensions – Widths: C and D – Arch length (depth): B – Circumference (perimeter): A  Tooth Size Arch Length Analysis Introduction  Common factor in malocclusion is the discrepancy in size between the teeth and the space available in the dental arch – Crowding -most frequently and most obviously seen as arch length discrepancy  Tooth Size Arch Length Analysis Introduction  Common factor in malocclusion is the discrepancy in size between the teeth and the space available in the dental arch – Spacing -the opposite problem – excess space – is encountered less frequently but is no less important  Tooth Size Arch Length Analysis Introduction  Common factor in malocclusion is the discrepancy in size between the teeth and the space available in the dental arch – A third space related problem is discrepancy in size between the teeth of the upper and lower dental arch , which makes normal occlusion and contact relationship unattainable Rationale of Mixed Dentition Analysis Space Available Space Required Compare Space excess OK Space deficiency  Mixed Dentition Space Analyses  Help to estimate the amount of spacing or crowding which would exist for the patient if all the primary teeth were replaced by their successors the very day the analysis is done  Do not predict the amount of spacing or crowding two or three years later  Do not predict the amount of natural decrease in arch perimeter which may occur during the transitional period without the loss of teeth  Tooth Size Arch Length (Perimeter) Analysis Arch length discrepancy Tooth size discrepancy  Nance analysis  Bolton analysis Only  Moyers analysis – Permanent dentition – Mixed dentition – Estimate the overbite and overjet that will likely be – Estimate space availability obtained after treatment is during the transition from mixed finished dentition to permanent dentition – Improper occlusion and contact relationship: discrepancy in size between the teeth of maxillary and mandibular arch  Nance Analysis Arch length (perimeter) analysis in mixed dentition Hays H. Nance  Nance Analysis  A space analysis in the mixed dentition  Predicts the mesio- distal widths of the unerupted canines and premolars by using radiographs  Sum the total widths of the erupted central and lateral incisors  Space required = space necessary for alignment  Measure with brass wire the arch perimeter from the mesiobuccal surface of one permanent mandibular first molar around to the mesiobuccal surface of the other permanent mandibular first molar  Space available for alignment unervated teeth MeasuredwithXrays Bbu best x ray SometimesPA's  Nance Analysis  Space required – Total sum of the mesio-distal widhts of erupted and unerupted permanent teeth (only 5 -5) 2ndpremolar 2ndPremolar  Space available – Using brass wire to measure the arch perimeter from the distal of primary 2nd molar to the distal surface of primary 2nd molar on the other side  Space available – Space required = arch length discrepancy – + sign means excess space – - sign means crowding  r Nance Analysis Upper Right Upper Left Space Available Space Required Difference Lower Right Lower Left Space Available Space Required Difference  Tooth Size Measurement Space Required  Measure the greatest mesiodistal diameter of permanent teeth already erupted  Tooth Size Measurement Space Required Unerupted Teeth Measure any unerupted tooth from acurate bitewings  Tooth Size Measurement Space Required  Transfer the divider tips to the line  Repeat this process until all the anterior teeth and bicuspids are measured in both arches – First molars are not measured  Tooth Size Measurement Space Required  Measurement the total mesio-distal diameters of 5 -5  Tooth Size Measurement Space Required Right Left U Right 6.8 7.0 7.9 7.2 9.0 8.9 6.9 8.0 7.1 6.8 U Left 5 4 3 2 1 1 2 3 4 5 L Right 6.9 7.1 6.9 6.3 5.7 5.5 6.0 7.0 7.2 6.9 L Left  Tooth Size Measurement Space Required Right Left U Right 6.8 7.0 7.9 7.2 9.0 8.9 6.9 8.0 7.1 6.8 U Left 5 4 3 2 1 1 2 3 4 5 L Right 6.9 7.1 6.9 6.3 5.7 5.5 6.0 7.0 7.2 6.9 L Left U Right U Left 37.9 mm 37.7 mm 75.6 mm Upper Sum U/L 32.9 mm 32.6 mm 65.5 mm Lower L Right L Left  Nance Analysis Upper Right Upper Left Space Available Space Required 37.9 mm 37.7 mm Difference Lower Right Lower Left Space Available Space Required 32.9 mm 32.6 mm Difference  Nance Analysis Upper Lower Space Available Space Required 75.6 mm 65.5 mm Difference Tooth Size Measurement Space Required Space required Arch Length (Perimeter) Measurement Space Available  Cut a length of 0.25 soft brass wire approximately 4 inches long  Adapt the wire to the normal arch shape Arch Length (Perimeter) Measurement Space Available  Mark the wire at the mesial contact points of the permanent first molars  Cut the wire at the contact points and straighten  Measure the wire with a caliper or a ruler Arch Length (Perimeter) Measurement Space Available Space available  Nance Analysis Upper Lower Space Available 71.1 mm 59.2 mm Space Required 75.6 mm 65.5 mm Difference - 4.5 mm - 6.3 mm Positive (+) signs means excess of space Negative (-) signs means crowding To get this space you can protrudetheanteriorteeth extraction would Palatal expander Inthiscaseweleftif havetoomuchspace Interproximalreduction weextractthepremolars  Interpretation  If the space available is greater than the tooth size, it is interpreted as excess arch length  If the tooth size is greater than the space available, the difference will indicate the amount of crowding which exists ans to this analysis teethmayberotated distortion maybedifficulttogetbitewings No cast non compliant Pt  Nance Analysis Disadvantage  Moyers Analysis  Introduced by Robert E. Moyers – Center for Human Growth and Development – University of Michigan, Ann Arbor  The purpose of a mixed dentition analysis – To evaluate the amount of space available in the arch for succeeding permanent teeth and necessary occlusal adjustments  To derive the sizes of unerupted canines and premolars from the knowledge of the sizesof permanent teeth already erupted (Probability Tables)  Moyers Analysis  Mandibular incisors are chosen for measurements – Early in the mixed dentition – Easily accurately measured – High correlation between the sizes of the mandibular incisors and the combined sizes of the canines and premolars in either arch – Little tooth size and shape variations in comparison with maxillary incisors – Very rarely congenitally missing 18h werupgisors.es  Moyers Analysis  Advantages of Moyers Analysis – Minimal systematic errors – Equal reliability by the beginner or the expert (it does not require sophisticated clinical judgement) – It is not time consuming – No need for special equipment or radiograph – It can be done with dental casts (advised) or in the mouth – Used for both maxillary and mandibular arches  Moyers Analysis Space Available 1. Set the Boyle gauge to a value equal to the sum of the widths of right central and lateral incisors 2. Place one point of the gauge at the midline between centrals and let the other point lie along the arch perimeter on the right side and mark it with a pencil 3. Repeat this process on the left side 4. Measure the distance from the point marked on the model to the mesial surface of 1st permanent molar (Space available for 345) Space available for 345  Space Available Measurement 11.5mm 19.5 mm 19.2 mm  Moyers Mixed Dentition Analysis Space Available Mandible Right Incisors Left Incisors Mandibular incisors width (measured) 5.5 +6 = 11..5mm 5.5 +6 = 11.5mm Distance from the point marked after aligning the incisors to mesial of the 1st 19.2 mm 19.5 mm permanent molar (Space available) Width of cuspid and bicuspid (predicted) 5 + 4+ 3 3 + 4 + 5 11.5mm (Space required) Arch length (perimeter) discrepancy Space available  Moyers Analysis Space Required  Measure width of each lower incisor  Record the widths on the chart 23 mm 5.5 + 6 + 6 + 5.5 = 23 mm  Mixed Dentition Analysis Mandible Right Incisors Left Incisors Mandibular incisors width (measured) 5.5+6 = 11.5mm 5.5+6 = 11.5mm Distance from the point marked after aligning the incisors to mesial of the 1st 19.2 mm 19.5 mm permanent molar (Space available) Width of cuspid and bicuspid (predicted) 5 + 4+ 3 3 + 4 + 5 (Space required) Total Lower incisors (2-2)= 23 mm Arch length (perimeter) discrepancy Apply 23 mm to probability table to find predicted width of 345 Probability Table it O Probability Table  Probability Table we'llalwaysusethe widthsfthe incisors to calculated the M Dwidthof the canines DM in both Arch Butwe'll use a differenttablefor Total sum of the width of L 2-2 use 75 fratwas The value at the 75% level of confidence is chosen as the estimate, since it has been found to be the most practical from a clinical standpoint. Predicted size of U 3 + 4 + 5  Moyers Analysis Space Required Mandible Right Incisors Left Incisors Mandibular incisors width (measured) 5.5+6 = 11.5 mm 557+6 = 11.5mm Distance from the point marked after aligning the incisors to mesial of the 1st 19.2 mm 23 mm 19.5mm permanent molar (Space available) Wi dth of cuspid and bicuspid (predicted) 5 + 4+ 3 3 + 4 + 5 Éthis isn't (Space required) Estee.se h gettheirAVG Ar ch length (perimeter) discrepancy Total sum of 4 lower incisors = 23 mm  Moyers Analysis Space Required Mandible Right Incisors Left Incisors Mandibular incisors width (measured) 5.5+6 = 11.5 mm 5.5+ 6= 11.5 mm Distance from the point marked after aligning the incisors to mesial of the 1st 19.2 mm 19.5 mm permanent molar (Space available) Width of cuspid and bicuspid (predicted) 5 + 4+ 3 3 + 4 + 5 22.2 mm 22.9mm (Space required) Arch length (perimeter) discrepancy - 3 mm - 3.4mm Total of 6.4 mm of arch deficiency in the mandibular arch  Moyers Analysis Space Available - Maxilla Right Incisors Left Incisors Maxillary incisors width (measured) 8.8+7.1 = 15.9 mm 8.6+7.1 = 15.7 mm Distance from the point marked after aligning the incisors to mesial of the 1st 21.5 mm 21.6 mm permanent molar (Space available) Width of cuspid and bicuspid (predicted) 5 + 4+ 3 3 + 4 + 5 21.6 mm (Space required) Arch length (perimeter) discrepancy 21.5 mm Total Lower Incisors: 23 mm  Moyers Analysis Space Required Maxilla Right Incisors Left Incisors Maxillary incisors width (measured) 8.8+7.1 = 15.9 mm 8.6+7.1 = 15.7 mm Distance from the point marked after aligning the incisors to mesial of the 1st 25 mm 25 mm permanent molar (Space available) Width of cuspid and bicuspid (predicted) 5 + 4+ 3 3 + 4 + 5 (Space required) Arch length (perimeter) discrepancy Total Lower Incisors: 23 mm  Moyers Analysis Maxilla Right Incisors Left Incisors Maxillary incisors width (measured) 8.8+7.1 = 15.9 mm 8.6+7.1 = 15.7 mm Distance from the point marked after aligning the incisors to mesial of the 1st 21.5 mm 21.6 mm permanent molar (Space available) Width of cuspid and bicuspid (predicted) 5 + 4+ 3 3 + 4 + 5 22.6 mm 22.6 mm (Space required) Arch length (perimeter) discrepancy - 1.1 mm - 1 mm Total of 2.1 mm of arch deficiency in the maxillaryarch  Moyers Analysis Lower Arch  Lower incisors are measured to – Establish the space available for the lower unerupted canines, first, and second premolars – Predict the size of the lower unerupted canines, first, and second premolars  Moyers Analysis Upper Arch  Upper incisors are measured – Establish the space available for the upper unerupted canines, first, and second premolars  Lower incisors are measured – Predict the size of the upper unerupted canines, first, and second premolars  Moyers Analysis  Maxillary incisors are NOT used for predictive procedures – Too much variability in size and shape – Poor correlation with other groups of teeth i Bolton Tooth Size Analysis  Bolton Analysis (1952)  This analysis is based on the ratio between the sums of the mesiodistal widths of maxillary and mandibular teeth derived from 55 patients with perfect Class I occlusion – Estimate the overbite and overjet that will likely be obtained after treatment is finished – Estimate the effects of extractions on posterior occlusion and incisor relationship – Identify occlusal discrepancies produced by interarch tooth size incompatibilities  Bolton Analysis  55 cases with excellent Class I occlusion – 44 orthodontically treated – 11 untreated with full dentition  Teeth measured – Mesiodistal widths of 12 maxillary teeth – Mesiodistal widths of 12 mandibular teeth – Overbite (in terms of %) – Overjet (in terms of mm)  Bolton Analysis  Measure the greatest mesio – distal width of each tooth with dividers  Transfer the divider tips to the lines beginning at the midline  Continue on both sides of the midline until the first molars are measured  Bolton Analysis BIigymiiiin.it  Anterior ratio  Overall ratio in L6 -6 L3 -3 X 100 = 91.3% U 3 – 3 X 100 = 77.2% U 6 –6 Total size discrepancies have been conventionally described as relative excess in tooth structure in one arch  < 77.2% - excess in U 3-3  < 91.3% - excess in U 6-6  > 77.2% - excess in L3-3  > 91.3 % - excess in L 6-6  Bolton Analysis Ideal Occlusion  OB: 31.3 % / OJ: 0.74mm  Anterior Ratio – Range: 74.5 – 80.4 – Mean: 77.2 – SD: 1.65  Overall Ratio – Range: 87.5 – 94.8 – Mean: 91.3 – SD: 1.91  Bolton Ratio Analysis Form (Overall Ratio) 89.5 0.94 94 95 Example 1: The sum of L6-6: 89.5 mm The sum of U6-6: 95 mm Overall ratio: 94.4% 89.5 86.7 2.8  Bolton Ratio Analysis Form (Anterior Ratio) 35.1 0.722 72.2 48.6 Example 2: The sum of L3-3: 35.1 The sum of U3-3: 48.6 Anterior ratio: 72.2% 48.6 45.5 3.1  Bolton’s Ratio-Anterior Ratio  Patient 1 8% 91% Mild Bolton discrepancy mm mm Normal OJ  Patient 2 Significant Bolton discrepancy Excess OJ Need to reduce the tooth size of mm mm U3-3  How to Manage Bolton Size Discrepancies in the Anterior Segment? Problem Solution Generalized large mandibular teeth 1. Reduce the width of the lower incisors relative to maxillary anterior teeth (interproximal stripping – not more than 2 to 2.5 mm) + increase lingual crown torque (crown inclination) 2. Extraction of one mandibular incisor Generalized small maxillary anterior 1. Mild discrepancy: increase the distal root teeth relative to mandibular anterior tip (increase the angulation of the teeth) teeth 2. Significant discrepancy: combined orthodontic restorative technique (i.e: veneers, proximal build up) Small maxillary lateral incisors Restoration (Veneers, proximal build ups) Large Mandibular Teeth Relative to Maxillary Anterior Teeth  Generalized Small Maxillary Anterior Teeth