skeletal growth prediction and Age estimation

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<p>Slide 1</p> <p>Skeletal Growth prediction&amp;Age Estimation</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>ContentsIntroductionGnomic growth and logarithmic spiralArcial growthRicketts cepahlometric predictionPrediction of mandibular growth rotations </p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Mathematical model for prediction of craniofacial growthVTOTooth mineralizationSkeletal maturity indicator</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Introduction </p> <p>It is not possible to predict how a patient is going to respond to a particular treatment.Variability is expectedProffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p> Patients growth pattern Variability</p> <p> Effect of treatment on growth</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>In the absence of growth, treatment responses are reasonably predictable GROWTH IS NOT.Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>The goal of growth prediction is to reduce the clinicians ignorance of the future</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>What are we interested in predicting in the craniofacial complex?1. Future size of a part -The prediction of future size is primarily a problem of predicting future increments which are to be added to a size that is already known.</p> <p>Eg: prediction of length of the mandible</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p> 2. Relationship of parts The most important prediction for the clinician is the future relationship of parts, that is the future facial pattern.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>3. Timing of growth events Because growth does not proceed evenly, certain facial dimensions demonstrate marked change in their velocity curves. These spurts make predictions much more difficult. </p> <p>If one were to predict a spurt, we might want to predict the a) time of onset. b) duration of increased rate of growth c) rate of growth during the spurt.Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>4. Vectors of growth- Most predictive method presume a continuation of the pattern first seen.The presumption is made that the vectors of the growth present at the time of prediction will remain. However this is not true..Mandible which grow vertically for a period of time can start to grow horizontally!!!Can such changes in growth direction be predicted???Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>5. Velocity of growth- It would be of use to know the future expected rate of growth especially during pubescent spurt.</p> <p>6.Effect of orthodontic therapy on any of the above predicted parametersWhat effect therapy is having on the predicted and actual growth of one specific face</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>How well can we predict these parameters???</p> <p>Future Size Complex craniofacial growth Any simple series of size prediction is not clinically useful.Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Relationship of parts Harvold, Johnston, Ballach predicted maxillo mandibular relationship.None were accurate</p> <p>Timing and growth eventsHunter &amp; Miller reported the shape of the face as roughly related to the timing of the pubuscent spurt.Frisancho- predict the individual spurt in stature from noting the time of calcification of the sesamoid bone </p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Vectors of growthThere is no means of anticipating change in the direction of growthPredicting vector is not same as predicting changes in the vector.</p> <p>VelocityNot much attention is given to thisProffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>The effect of orthodontic therapy on growth Ricketts method- sets the prediction and then works to make them come trueProffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Gnomic growth and logrithmic spiralWhat is gnomic growth? The process where upon the addition to a body leaves the resultant body similar to the original is called gnomic growth.DArcy Thompson classified the sea shells in accordance to their pattern of enlargement and developed an equation. Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>The Nautilus offers 2 fundamental characterstics-1. The shell grows in size but does not change its shape new growth</p> <p>2. Its gnomic growth can be described by a particular kind of curve- the logarithmic or equiangular spiral.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>The spiral is characterized by the movement of a point away from the pole along the radius vector with a velocity increasing as its distance from the pole</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Logarithmic growth of human mandibleThere are several functional conditions which are not violated during orofacial growth- one of these is neural innervations which must never be subjected to external loading.Craniometric studies were performed on American Indian skull .they are representative of mandible with fetal, deciduous, mixed and adult dentition.Small lead shots were fixed to foramen ovale. Mandibular foramen.&amp; foramen mentalProffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Lateral x-rays effectively outlined the pathway of the Inf. Alveolar nerve.All the 3 neural foramina at all ages fit precisely upon a single mathematically defined, logarithmic spiral.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Another longitudinal and cross sectional clinical growth data showed that these foramina moved along the same logarithmic spiral in geometric fashion, with the gradient of motion directly increasing with the distance of the foramina from the cranial base. ie mental foramen moves most and the foramen ovale least.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>In the fetal period the 3 foramina are relatively near the origin of the spiral and at the same time they are placed nearer to each other than at later stage. This produces a flatter curvatre hence gonial angle is relatively flat</p> <p>With growth due to increase in distance ramus becomes straight relative to corpus and gonial angle acute.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>During all stages of development the corpus stays in essentially a horizontal position. At the same time the mandible curves down the logarithmic spiral course of the inferior alveolar nerve.Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Arcial growth Ricketts in 1972 developed a method to determine the arc of growth of the mandible.PRINCIPLE:A normal human mandible grows by superior anterior apposition at the ramus on a curve or arc which is a segment formed from a circle. The radius of this circle is determined by using the distance from mental protrubence (Pm) to a point at the forking of the stress lines at the terminus of the oblique ridge on the medial side of the ramus( point Eva)Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Landmarks Xi point- The deepest point on the subcoronoid is selected as R1.R2 is selected directly opposite to it on post border of ramus.R3 is selected at the depth of the sigmoid notch.R4 is directly on the lower border of ramus.The centroid of the rectangle formed is called Xi point.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Supra pogonion- It is a point located at the superior aspect of symphysis.It is labelled PmThis is substantiated as a reference point because-1. It is the site of a reversal line (Enlow)2. Stable unchanging bone in this area of bone (Bjork).</p> <p>Point Dc It is a point at the bisection of condyle neck</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Point Eva- it is a biologic point as it is located over the point of forking of the stress line in the ramus.Ramus reference point (RR) is the point halfway between Xi point and R3 on the anterior border of ramus.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Construction of growth arc:1 Point RR and R3 are connected. Mid point of RR and R3 is pt Eva2 Take pt Eva Pm as radius- circle is drawn 1. taking eva as a centre 2. taking Pm as a centre.3 The point of intersection is TR (True radius) taking this as a centre an arc is drawn.4 Where this arc crosses sigmoid notch is called Murray point.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Steps in growth prediction Step 1 amount of growth on arc- 2.5mm From pt Mu the mandible is grown out on the arc at the sigmoid notch about 2.5mm. cutoff for males=19yrs females= 14.5yrs </p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Step 2 Coronoid upwards &amp;outwards 0.8mm/ yr Condyle - upward &amp; backward - 0.2 mm / yr</p> <p> Step 3 - Drift of gonial angle Females- no addition Males - 0.2 mm / yr</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Step 4 complete forcasting of the mandibular form Connections from coronoid process RR 0.4mm/yr determine space available for 3rd molar</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>By constructing the growth arc, growing the mandible on the arc, extending and drifting the angular process, this forecasting technique is tested.Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Drawbacks of arcial growth prediction</p> <p>1. It relies heavily on the operators skill in tracing the cephalogram.2. Mitchell &amp; Jordan (1975) concluded Ricketts uses chronological age rather than the skeletal age. If the patient is in a growth spurt or lag phase it will alter the result.3. The growth increments constants are for a fixed population.Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Ricketts cephalometric or short term prediction The changes in the face during treatment were thought to be influenced by a phenomenon within TMJ complex. 1. The changes in the angle of cranial base to a more acute or obtuse relationship. 2. Forward or backward movement of the condyle that influenced the chin behavior. </p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Procedure for growth estimationClass II Div 1 case was selected to demonstrate the procedure.For growth estimation work, the cranial plane basion-nasion (Ba-Na) plane is employed.It can be studied in following steps:STEP 1: 1. Projection of probable changes in the basi cranium It includes Points N, S, &amp; Ba. a.) Sella starting point. Average expectancy for increase along SN Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p> pubertal spurt 1mm / yrMixed dentition 0.5 0.7 mm / yr.</p> <p>b) Expected changes between sella &amp; Basion change in length is 3/4th of S-N.</p> <p>c.) Establish Expected Ba-N Connect the new S &amp; N &amp; Ba formation of new basicranium.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>STEP 2:Predeterming the behaviour of condyleCondyle position remained same in 60% of casesDownward &amp; forward movement of Ar &amp; Ba similar after the age of 6Superimposing Ba- N and registering Ba will reveal the future condylar position..</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>STEP 3:Ptm is outlined-evaluation of maxillary growth, coronoid pr.Superimposing of SN and registering at S showsDownward dropping of this fissure.Tip of the coronoid process is located 3mm forward to ptm at both start and completion of Treatment.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>STEP 4:Construction of condylar axisFrom the centre of condyle to antegonial angle.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>STEP 5:Contemplation of growth of condyleEstimated on the condyle axis .During Rx 2mm of growth / yr upto 9yrsDuring puberty = 3 or 4 mm / yr may be expected The assessment of condylar growth permits the construction of the post. Border, gonial angle, sigmoid notch,&amp; ant. Border of ramus.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>STEP 6: assessment of remaining mandibleRotation of mandibular plane untill the change agrees with the estimate of change for that caseForward direction of condyle lower mandibular plane angleBackward condylar growth - higher mandible plane angle.</p> <p>STEP 7:Lengthening of body of mandibleIt is slightly greater than S-N plane1.5 mm / yrChanges in the symphysis are plotted</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>STEP 8:Facial plane and Y axis is constructedSuperimposition on the BA-N plane will indicate the direction of growth of mandible.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Position of MaxillaStep1 Increase in face height( vertical changes)Facial plane is superimposed &amp; registered on N40% above ANS60% of TFH increase is due to the denture area ie below ANS.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Step 2 Horizontal position of maxillaIt is postulated from the tendency of S-Na to remain constant to Ba-NPt A is dropped parallel with line NAGreat amt of bodily retraction- Pt. A will be moved back as much as 3-5 degree.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>3. future facial convexity is determined by predicted behavior of Pt. A</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>4. Descent of the palate is forecastPost nasal spine drops parallel to ptm</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p> Soft tissue behavior Nose superimposing of the palatal bone and registering on ANS2mm of growth of noseProfile outlined is then constructed to the area below nose.</p> <p>Proffit W, Fields H, Sarver D;Contemporary Orthodontics 4 ed 2007; Elsevier</p> <p>Upper Lip- severely protruding cases- 2-4 mm increase in thicknessModerate protrusion...</p>

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