Growth Rotations
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INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com
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Introduction Maxillary rotations Prediction of growth rotation Growth rotations- facial development, tooth eruption Clinical implications www.indiandentalacademy.com
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Introduction  Facial growth in terms of rotations is important in the understanding of the development of the craniofacial complex.  The introduction of the implant method by Bjork (1955)made it possible to study the rotations of the maxilla and mandible.
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MAXILLARY ROTATIONS Less easy to divide maxilla into a core of bone and a series of functional processes. There are no areas of muscle attachment analogous to those of the mandible. Implants placed above the maxillary alveolar process show that the core of the maxilla undergoes a small degree of rotation www.indiandentalacademy.com
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ENLOW’S CONCEPT
Maxillary Rotations
Displacement
Remodeling
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Displacement Primary displacement occurs-antroinferior direction. Sutures are tension adapted-cannot grow by pushing-apart. Stimulus for sutural remodeling is due to the displacement.
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 Secondary displacement-
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Growth of the brainSpinal cord aligns vertically. Orbits rotate and align so that they point forward. This plane determines the direction of nasomaxillary development. www.indiandentalacademy.com
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The maxillary tuberosity located just below the floor of the orbit. The tuberosity is aligned perpendicular to neutral geometric axis of the orbit.
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 The hard palate conforms to the alignment of maxillary nerve before it enters the orbit.
 The plane projects to inferior most point in the occipital fossa. www.indiandentalacademy.com
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Remodeling Lacrimal suture: key growth mediator. Sutural system of lacrimal bone –slippage for multiple bones. The maxilla slides down along its orbital contacts. Lacrimal bone – remodeling rotation.
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Drift of the teeth  As the maxilla and mandible enlarge, dentition drifts-horizontally and vertically.  The whole tooth and its socket move.
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Nasal and palatal remodeling
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The balance between greater and lesser amounts of remodeling in the posterior & anterior parts of the maxilla is the response to clockwise/ counterclockwise rotatory displacement of middle cranial fossa. Compensatory remodeling rotation of the nasomaxillary complex-sustains its proper position relative to the neutral orbital axis. Remodeling also occurs as bones assume new positions with expansion of the soft tissue matrix. www.indiandentalacademy.com
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1-2-direct relocation. 2-3- primary displacement
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BJORK’S CONCEPT Longitudinal study done by implant method. Lateral implants:4yrs of age -inserted laterally in the zygomatic process of the maxilla (2 on each side). -increase in distance between the implants on the frontal film - increase in the width in the median suture at the level of the 1st molars.
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Anterior implants:10-11yrs of age -inserted below the anterior nasal spine. -one on each side of the median suture at level with the apices of the central incisors. - increased distance bw the implants measured on frontal film - growth in the width in the median suture at the level of the incisors.
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 Implant line-Tip of 1 anterior implant to midpoint of 2 lateral implants. -Change in the inclination of implant line to the S-N line-vertical rotation of maxilla in relation to cranial base.
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Maxillary growth-Lateral implants.  Height
(4 yrs)
-growth at frontal and zygomatic process. -apposition at lower alveolar process and eruption of teeth. -apposition at floor of the orbit. -nasal floor lowered down. www.indiandentalacademy.com
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Lateral implants-vertical component calculated at right angles to S-N. Sutural lowering -11.2mm Apposition at the floor of the orbit-6.4mm. Lowering of nasal floor4.6mm Appositional growth in height of alveolar processwww.indiandentalacademy.com 14.6.mm
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 Width -growth in the median suture. -appositional remodeling in the outer aspects. -Enlow-widening of hard palate mainly result of remodeling. -Persson, Melsen-growth in median suture upto adolescence.
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 Implants study show -median suture growth-6.7mm -outer aspect of maxilla-9.5mm -growth in the median suture follow the same curve as their growth in body height.
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Growth of maxilla in 3-d anterior and lateral implants(10-11 yrs)
 Length-
-sutural growth towards palatine bone by apposition on tuberosities. -anterior surface was thought to be resorptive; unchanged when studied using implants.
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Sagittal growth studied in relation to infrazygomatic crest.
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ROTATIONS Transverse plane Vertical plane.
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Transverse mutual rotation of the two maxillae: Joining anterior and lateral implants on each side a triangle is constructed with sides of constant length.
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Lateral implants increased 3mm against 0.9mm of the anterior implants. Thus, the lateral implants separate more. This reduces length of maxilla in mid sagittal plane. The distance between 1st molars increases more than canines
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VERTICAL ROTATIONS  Superimposition shows parallel lowering of nasal floor.
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 Implant studies-maxilla undergoes vertical rotation. -inclination of anterior cranial base to nasal floor is maintained by compensatory remodeling. -forward rotation-anterior resorption & deposition posteriorly.
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 Backward rotation-Rotates down anteriorly.
-posterior resorption more than anterior.
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Prediction of growth rotation
 Rotational prediction has been done in various ways: -Bjork’s method -Logarithmic spiral (Moss) - Arcial growth prediction (Ricketts)mandible rotates in the form of an arc.
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BJORK’S METHOD LONGITUDINAL METRIC STRUCTURAL
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LOGITUDINAL  Longitudinal method-annual cephalograms. -natural reference structures. -rotation can be read from angle formed between S-N lines of 2 ages. www.indiandentalacademy.com
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1.
Tip of the chin.
2.Inner cortical structure at the inferior border of the symphysis. 3. Mandibular canal. 4. Lower contour of molar germ .
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Limitations :  The pattern of growth is not constant and changes by adolescence.
 It permits the observation of changes in the sagittal jaw relation, but changes in the vertical jaw relation are masked. Periosteal remodeling at the lower border masks the actual rotation.
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Metric It aims at a prediction of facial development on the basis of the facial morphology, determined from single x-ray film. Statistical studies show –possibility of predicting intensity & direction of growth from size and shape on childhood is not feasible. Very weak correlation found between inclination of mandible at 12years and rotation during adolescence. www.indiandentalacademy.com
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Structural  Based on information concerning the remodeling process gained from implants.  If implants are not used, single radiograph is used to predict mandibular rotation.  Specific structural features develop as a result of remodeling in a particular type of rotation.
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Structural signs of growth rotation Seven signs-extreme growth rotation.
Considered in relation to direction of condylar growth.
Greater the number-more reliable the prediction. www.indiandentalacademy.com
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Inclination of condylar head Curvature of the mandibular canal The shape of the lower border of the mandible Inclination of the symphysis Interincisal angle Interpremolar and molar angles Lower anterior face height www.indiandentalacademy.com
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Condylar Inclination
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Mandibular Canal
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Lower Border & Inclination of Symphysis
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Inter Incisal Inclination
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Inter Molar Relation
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Condylar Inclination
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Mandibular Canal
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Lower Border & Inclination of Symphysis
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Inter Incisal Inclination
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Inter Molar Relation
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Mandibular morphologic characteristics in relation to various facial types and jaw rotations.- Dr. Violet Barbosa  Had divided the cases into 3 groups: Group A- Forward rotation. Group B- Normal rotation. Group C-Backward rotation. www.indiandentalacademy.com
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Index I = S-tgo/ N-Gn x 100 Lower gonial angle Inclination of condylar head Shape of lower border of mandible Inclination of symphysis Interincisal angle Intermolar angle Depth of antegonial notch
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 Results: Index I, Lower gonial angle , Inclination of condylar head and Inclination of symphysis could be relied upon, to predict the type of rotation of the mandible to a limited extent. www.indiandentalacademy.com
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Facial pattern and Tooth eruption
There is considerable difference in development and facial form. Forward rotation-normal underdeveloped anterior face height.
excess-
Backward rotation-overdevelopment of anterior face height. Type of rotation depended on the condylar growth direction and intensity. www.indiandentalacademy.com 56
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Tooth eruption  The rotational pattern influences the magnitude and direction of tooth eruption.
 Superimposition on lower border of mandible gives impression-teeth erupting vertical
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Implants-forward directed path of eruption in case of forward rotation. Forward migration of the entire dentition. Molar eruption more than anterior. Lower molar teeth more upright than upperincrease in interpremolar and intermolar angles.
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Average values:  Maxillary arch -Mesial migration I molars-5mm -central incisors-2.5mm Shortening of arch-1mm+1.5mm
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Average values: Mandibular arch Mean forward migration of mandibular molars 5.2mm. Lower central incisors-3.2mm. Shortening of the dental arch-2.0mm.
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Backward rotation-lower anterior teeth-tipped backward. Reduced alveolar prognathism. Molar eruption-diminished.
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 Proffit -The lower mandibular teeth erupt in upward and forward direction. -Forward rotation –alters the path of eruptiondirected posteriorly.
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Clinical implications Extreme forward rotation
Short face type “Square jaw” type Low mandibular plane angle Skeletal anterior deep bite Crowding of anterior teeth Palatal plane is nearly horizontal. smile - lower incisors are visible with the upper incisors hidden behind the www.indiandentalacademy.com upper lip.
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Backward rotation Long face type “Round jaw” type Steep mandibular plane angle Skeletal anterior open bite Dental protrusion Negative inclination of palatal plane
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 Can have various combinations of rotations of maxilla and mandible.
 Convergence or divergence of jaw bases leads to various types of malocclusions.
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TREATMENT OF SKELETAL PROBLEMS IN PREADOLESCENT CHILDREN GROWTH MODIFICATION Before the adolescent growth spurt ends
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FUNCTIONAL JAW ORTHOPEDIC APPLIANCES: MANDIBULAR DEFICIENCY REMOVABLE:
Activator, Bionator, Frankel 1&2,Bimler’s appliance & Twin block appliance FIXED:
Herbst appliance, Jasper jumper www.indiandentalacademy.com
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MANDIBULAR EXCESS: FUNCTIONAL JAW ORTHOPEDICS Frankel 3 appliance Reverse activator
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MANDIBULAR EXCESS extra oral force orthopedic chin cup occipital pull chin cup vertical pull chin cup Steep mandibular plane angle & excessive lower facial height. www.indiandentalacademy.com
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ADULTS BILATERAL SAGITTAL SPLIT OSTEOTOMY
SET BACK
ADVANCEMENT
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Maxillary excess:For restriction of maxillary growth in growing individuals appliances like 1.Headgear 2.Functional appliances
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Cervical head gear: used in patients with horizontal growth pattern with reduced lower facial height.
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Occipital pull Head gear:Used in long face patients with high mandibular plane angle.
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 Maxillary Deficiency: Growth modulation in sagittal plane can be done : 1.face mask
Delaire facemask
2.reverse functional appliances.
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Petite facemask
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Combination of maxillary excess and mandibular deficiency
High pull headgear with functional appliance www.indiandentalacademy.com
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References Contemporary orthodontics - William.R.Proffit(2nd &3rd ed.) Essentials of of facial growth - Donald.H.Enlow. Dentofacial orthopaedics with functional appliances -Thomas M.Graber, Thomas Rakosi, Alexandrer G.Petrovic. www.indiandentalacademy.com
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Facial growth and facial orthopedics. -van der Linden. Determinants of mandibular form & growth (CFGS) Monograph-4 Factors effecting growth of the midface (CFGS) Monogrph-6. The rotation of mandible resulting from growth;Its implications in orthodontic treament -F.F.Schudy-AO 1965.no.1,36-50. www.indiandentalacademy.com
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Prediction of growth rotation - A.Bjork-AJODO-1969,jun 39-53.
Facial development and tooth eruption :an implant study at the age of pubertyA.Bjork,V.Skieller AJO-DO 1972,62,4;339-383.
Normal and abnormal growth of mandible.a synthesis of longitudinal cephalometric implant studies over a period of 25 www.indiandentalacademy.com 81 years.A.Bjork,V.Skieller.EJO-1983,5;1-46.
The puzzle of growth rotation. J.M.H.Dibbets – AJO-DO June 1985 ,87,6;473-480. Mandibular rotations – concepts & terminology Beni Solow & William Houston J B-EJO1988,10;177-179. Mandibular rotation and enlargement. J.M.H.Dibbets.AJO-DO July 1990,29-32. Mandibular morphologic characteristics in relation to various facial types and jaw rotations.- Dr. Violet Barbosa Aug 1996.
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