Classification of Sassoni Skeletal Facial types

1. 1 Skeletal facial types Skeletal facial types Sassoni 1969 Sassoni 1969 Prepared by Prepared by Dr: Mohammed Alruby Dr: Mohammed Alruby ىقيدص نم يودع اهب تفرع ريخ لك دئادشلا الله يزج Skeletal Skeletal F Facial types acial types -- -- Sassoni 1969 Sassoni 1969 Dr. Mohammed Alruby Dr. Mohammed Alruby

2. 2 Class: used for grouping of dental malocclusion Types: restricted to grouping of skeletal disproportions Classification: is the identification of number of characteristics that seen together, present enough similarities to be included in the same group. Skeletal deep bite: Positional deviation: == the four planes of the face 1-Supraorbital (line tangent to the superior of the roof of the orbit and anterior clinoid) 2-Palatal plane 3-Occlusal plane 4-Mandibular plane Are nearly parallel to each other, this carries the center 0 of convergence of four planes far away from the profile == the anterior arc (drown from center 0 and nasion) is nearly straight line == the midface (palatal complex) is usually retruded creating concave profile == the posterior vertical chain of muscles (masseter, internal pterygoid and temporalis) is attached anteriorly on the mandible and stretch nearly in straight line vertically == molars usually under the impact of masticatory force of this chain of muscles == cranial base angel (supra-orbital to clavius) is small, that affect the position of glenoid fossa and therefore the condyle more anteriorly often directly below the Sella turcica == in compensation of anterior positioning of condyle, the gonial angle (ramus to corpus) is small and the posterior border of ramus is nearly vertical == at the dentition level the upper and lower incisors have their long axis nearly parallel and vertically extruded whereas the molars are intruded. Dimensional deviations: == the total posterior facial height (Sella to Gonion) nearly equal to the total anterior facial height (supra-orbital to menton) == lower facial height (ANS to Me) is smaller than upper facial height (Sup-or- ANS) == facial breadth as bi-gonial diameter tend to equal the total face height giving square appearance of the face from the frontal view == gonial process are flared laterally indicate strong masseter action == long ramus tends to equal the length of corpus == large coronoid process indicates strong temporalis muscle == mandibular symphysis is short vertically and broad anteroposteriorly == distance between B point to Gonion is large creating chin button == lack of anti-gonial notch of mandible leading to rocking of lower border of mandible = skull usually round with bulging forehead, nasion is deep seated posterior for frontal and nasal bones = broad nasal aperture = dental arches are in bidental retrusion relative to their bony bases. = dentition exhibits a tendency to small teeth, and high % of congenitally missing teeth = palatal vault is flat with broad maxillary dental arch and buccal cross bite == lips are thin with an excessive lip height relative to face height == usually deep furrow or sulcus between prominent chin and lower lip Skeletal Skeletal F Facial types acial types -- -- Sassoni 1969 Sassoni 1969 Dr. Mohammed Alruby Dr. Mohammed Alruby

3. 3 Factors in development of deep bite type: = besides the anatomic details, the vertical relationship of maxilla and mandible may be conductive to certain skeletal deep bite = lack of vertical growth between the cranial base and maxillary posterior teeth = excessive growth of ramus and posterior cranial base permits the mandible to rotate upwards = when teeth are reduced in size and number, dental arches oppose less resistance against closure = when posterior vertical chain of muscles is strong and anteriorly positioned, greater depressive action is transmitted to the dentition Skeletal open bite: Most characteristics are opposite to deep bite Positional deviation: = four planes of the face are steep to each other, the anterior arc follows the convexity of patient profile = posterior vertical chain muscles are arcuate and masseter is posterior to molars and bi- cuspids = cranial base angle and gonial angle are large = long axis of incisors forms a small inter-incisal angle = incisors are usually more extruded in open bite type; this extrusion is not sufficient to establish their vertical contact Dimensional deviation: == total PFH (S—Go) tends to half the AFH ( supr-Or to Me) == lower AFH exceeds UAFH whereas the reverse is true for posterior face, LPFH smaller than upper == facial breadth tends to be narrow giving ovoid appearance if frontal view == nasal aperture is narrow = short ramus with anti-gonial notch at its lower border = mandible seems to have retained its infantile characteristic with all its process under developed = temporal fossa is small suggestive of weak musculatures = narrow mandibular symphysis anteroposteriorly and long vertically with lack of chin prominence ++ teeth are large, crowding and bi-dental protrusion are often present ++ palatal vault narrow and high ++ wide mouth and broad lips ashort vertically relative to their skeletal support) and kept a part at rest ++ when the lips are forcibly closed, the mentalis muscle is displaced upward Factors in development of open bite type: = posterior half of palate is tipped downward and giving rise to a large palate-mandibular plane angle = the combination of excessive development of UAFH (cranial base to molars) and lack of development of PFH results in downward and backward rotation of mandible = because of short ramus and constricted pharyngeal space, these individuals keep tongue thrust for breathing and the thrusting is enhanced by dental open bite, and enlarged tonsils Skeletal Skeletal F Facial types acial types -- -- Sassoni 1969 Sassoni 1969 Dr. Mohammed Alruby Dr. Mohammed Alruby

4. 4 = narrow palatal vault reduces the necessary space and there is a tendency of tongue to protrude which is may be a factor for creation of bidental protrusion Skeletal class II: Positional deviation: 1-Long anterior cranial base, large cranial base angle 2-Short ramus and small gonial angle 3-Palate is tipped downward and backward The results of these combinations is protrusion of maxilla or retrusion mandible or both Dimensional deviation: Macro-maxilla: = it is possible in an individual face to find that all structures are normal in position but discrepancy in size may create class II type = palate with PNS normal in position but too long for the rest of the face = usually malar bone is also positioned anteriorly These individuals usually do not have a maxillary dental crowding Micro-mandible: = Corpus is short in absolute and relative dimension = usually Gonion in normal position, but as a result of short corpus, the chin is retrusive = mandibular incisors teeth held posteriorly, do not meet antagonist during eruption and over extrude, thus accentuate curve of spee = lower lip found behind the maxillary incisors Combination of positional and dimensional class II: = it possible for micro-mandible to be normal in position at the chin (corpus is short at Gonion) = macro-maxilla is not necessarily protrusive, since the excess in size may be present only at PNS Skeletal class III: Positional deviation: = defined as the presence of unfavorable characteristic of the open bite and deep bite = small cranial base angle, bringing the glenoid fossa more anteriorly relative to Sell turcica = palatal tipped upward at PNS and downward at ANS, that bringing the maxillary molars to high level when present together Dimensional deviation: Micro-maxilla: = palate is short often transversely with high vault = crowding of maxillary dental arch with congenital missing incisors, bicuspid and molars = crowding of incisors and canine due to constricted pre-maxilla =constriction of maxilla is associated with narrow apertures Macro-mandible: = excessive length of mandible may be located at neck, ramus and corpus = seldom excessive length of mandible anteroposterior without bi-condylar or bi-gonial breadth also being large Skeletal Skeletal F Facial types acial types -- -- Sassoni 1969 Sassoni 1969 Dr. Mohammed Alruby Dr. Mohammed Alruby

5. 5 = lower lip is tight against mandibular incisors tipping them lingually, symphysis supporting teeth is high and narrow, radiographically: there seems to be very thin layer of alveolar bone surrounding them = long styloid process = gingival recession and periodontal disease are often probably due to cross bite and disuse of the teeth Combination of dimensional and positional class III: Sometimes positional deviation in one direction compensate a dimensional excess as: == long ramus and corpus may be neutralized by small gonial angle or large cranial base angle (posterior positioning of glenoid fossa) These variations in size and position create an infinite number of composite class III types. Combination of vertical and anteroposterior type 1-Skeletal class II with open bite: = primarily an open bite type, positionally and dimensionally. In some instances, the retrusion of the mandible may be purely positional often as a result of its downward and backward rotation, this rotation is associated with extrusion of molars = if these interferences removed, the mandible would be permitted to rotate in closing direction, improving class II and open bite pattern 2-Skeletal class II with deep bite: = it is primarily deep bite type with dimensional deviation of the jaws anteroposteriorly = maxilla may be too long or mandible is too short = downward rotation improves the deep bite = during growth some improvement of this type can be expected, since the mandible can grow vertically and anteroposterior than maxilla 3-Skeletal class III with open bite: = primarily is open bite with palatal deficiency or large mandible = if correction of open bite is attempted by rotating the mandible in a closing direction, the protrusion of chin increased = on the other hand: if attempt is made to make reduction of the mandibular protrusion bt rotating the mandible downward and backward, the open bite increased 4-Skeletal class III with deep bite: = primarily skeletal deep bite associated with deficient palate or large mandible = if palate is deficient in young individuals, splitting of median sutures provides means of enlarging midface = is the mandible is too long, its downward and backward rotation may correct deep bite and class III, the prognosis is favorable Application of the classification on facial types 1-To distinguish between skeletal and dental malocclusion: To identify the severity of the problem, skeletal malocclusion is dental malocclusion with additional skeletal imbalance, furthermore malocclusion associated with skeletal imbalance are more stable than those of the dental arches alone 2-To evaluate physiologic differences: Skeletal Skeletal F Facial types acial types -- -- Sassoni 1969 Sassoni 1969 Dr. Mohammed Alruby Dr. Mohammed Alruby

6. 6 There is a variation of forces in the different masticatory muscle, that associated with facial types. By using a gnathic-dynamometer we can determine whether open bite and deep bite skeletal type show different degree or different level of masticatory forces, test showed that persons of open bite facial types demonstrate biting force between 50 –80 pound at molar level whereas persons of deep bite skeletal types show 150 – 200 pounds 3-Facial esthetics: Pluton 1967; made an initial attempt to indicate that large lower facial height were associated more often with displacing faces than anteroposterior variation or small lower face height 4-Racial frequencies: Comparison, among major racial groups show that, the Mongoloid and Negroid races have a greater tendency toward open bite skeletal type. This indicate that the classification of facial types should be modified for each race 5-Hereditary: Family line studies by Parado 1967 and Seitz show that, when both parents displayed open bite skeletal types there was strong tendency for offspring to have skeletal open bite 6-Growth: Sassoni and Nanda 1964 showed that mandibular growth is predominantly vertical in the open bite skeletal type, whereas the mandibular growth is horizontal in deep bite Addition to Angle’s classification Vertical dimension: Normally the maxillary buccal cups and incisal edges overlap the mandibular one There are two vertical types of malocclusion: 1-Open bite: One or more teeth in upper or lower do not reach the line of occlusion and do not meet their opposing teeth and it may be anterior or posterior 2-Deep bite: Or deep overbite is present when incisal edge of mandibular incisors occludes apical to the cingulum of maxillary incisors {because of wide variation in shape and position of cingulum, deep bite can diagnose when incisors overlap exceeds 40% of crown height of lower incisors} Bi-dental protrusion and Bi-dental retrusion: Bi-dental protrusion is a double malocclusion: both maxillary and mandibular dental arches are situated too far anteriorly in relation to facial skeleton Bi-dental retrusion is a double retrusion of maxillary and mandibular dental arches relative to their supporting jaws Skeletal Skeletal F Facial types acial types -- -- Sassoni 1969 Sassoni 1969 Dr. Mohammed Alruby Dr. Mohammed Alruby