Presented By: Dr. Girish G Sarada
Class II malocclusion
Introduction
Normal occlusionAngle’s view (Dental cosmos 1899)
Each dental arch describes a graceful curve, and that the teeth in these arches are so arranged as to be in the greatest harmony with their fellows in the same arch, as well as with those in the opposite
Division 1
a. Narrow upper arch, with lengthened and prominent upper incisors; lack of nasal and lip function, Mouth breathers
b. Same as a, but with only one lateral half of the arch involved, the other being normal, Mouth-breathers
Division 2
a. Slight narrowing of the upper arch; bunching of the upper incisors, with overlapping and lingual inclination; normal lip and nasal function
b. Same as (a), but with only one lateral half of the arch involved, the other being normal; normal lip and mouth function
In spite of Angle's important contribution, it became clear during the early part of the twentieth century that this classification system was inadequate to characterize the variety of manifestations of malocclusion presented by skeletal and dental discrepancies in all three planes of space
Differential diagnosis of Class II malocclusions - Robert E. Moyers et al
With the help of 697 subjects Use of computer statistics Combined analysis of skeletal and dental features Six subgroups based on horizontal variables
Type A
A normal skeletal profile
The occlusal plane is normal, as placed normally on its base
Maxillary dentition is protracted
Result – a class II molar relationship and a greater-than-normal incisal overjet and overbite
Type B
A class II skeletal profile due to midface prominence associated with a mandible of normal size
The mandible is in a normal relationship antero-posteriorly
The anterior cranial fossa tends to be flat
Type C
Generally smaller facial dimensions than other class II types
There is a markedly class II profile, even though both the maxilla and the mandible are farther back beneath the anterior cranial base than the normal
Lower incisors - tipped labially
Upper incisors - either upright or tipped off the base labially according to the vertical category
It is a severe skeletal class ii with a short mandible, a short maxilla, a squarish gonial angle, and a flat anterior cranial base
Type D
A retrognathic skeletal profile -- small mandible combined with a normal or slightly diminished midface
The mandibular incisors – either upright or lingually inclined
Maxillary incisors – extremely labially inclined
Type E
A severe “class II” profile – prominent midface and normal or even prominent mandible
Bimaxillary protrusion class ii malocclusions are more likely to be horizontal type e than any other
Both dentitions, in Type E, have a tendency to be forward on their bases and the incisors are often in strong labioversion
Type F
Large heterogeneous subgroup with the mildest class II tendencies
Not well-defined, rigid syndromal class II type but, rather, a loose collection of cases displaying some skeletal class II characteristics
The skeletal profile tends to be less severe than syndromal Types B, C, D, and E
The mandible is small, and the midface may be small
The tooth positions reflect the vertical subsets associated with Type F
HORIZONTAL TYPES
Type A
Type B
Type C
Type D
Type E
Type F
Vertical types
Type 1 a mandibular plane steeper than normal, steeper functional occlusal plane, palate which is tipped somewhat downward The anterior cranial base tends to be upward
The result -- an anterior face height - significantly greater than the posterior face height
Type 1 -- a “steep mandibular plane” or a “high angle” case
Type 2
Essentially a square face
The mandibular plane, functional occlusal plane, and palatal plane are all flatter than normal and are nearly parallel
The gonial angle approaches orthogonality & anterior cranial base more horizontal than normal
Under these conditions, the incisors tend to be vertical and in deep-bite
Type 3
Palatal plane which is tipped upward anteriorly
During growth, the upper face height does not keep pace with the total face height, resulting in a strong tendency to open-bite
When the mandibular plane is steeper than normal in vertical type 3, a skeletal anterior open-bite is inevitable
Type 4
Mandibular plane, the functional occlusal plane, and the palatal plane are all tipped markedly downward, leaving the lip line unusually high on the alveolar process in the maxilla
The gonial angle is obtuse
The lower incisors are tipped lingually
Vertical type 4 is among the most rare, severe, and anomalous of the vertical types
Type 5
Closely related to type 2 “the square face syndrome, ” and is found only in horizontal subgroups B and E
The mandibular and functional occlusal planes are normal
The palatal plane is tipped downward
gonial angle is the most squarish of all the types, resulting in a skeletal deep-bite
The lower incisors are found in extreme labioversion, whereas the upper incisors are nearly vertical
Vertical Type I --- Types C, D, and F
Vertical Type 2 -- found in all horizontal types, although it is the dominant feature of horizontal Types B and E
Vertical Type 4, as noted earlier, is a severe rare group limited to horizontal Type B
Vertical Type 5 is found predominantly in horizontal Types B and E
Etiology
Considered to be ‘multifactorial’
Lundstrom reported that in monozygotic twins 68% of concordance of having class II malocclusion than dizygotic (24%)
But when we see the same in case of open bite we find 100% concordance rate in monozygotic & 10% for dizygotic
So even with an identical genotype class II malocclusion does not always develop
According to Graber, the Aleuts – no Class II
South African blacks – 2.7%
Several investigators suggested additional etiological factors that particularly pertain to cl II div 2
a. Genetic predisposition :- Leech published a case report on identical twin, one having Div 1 & other Div 2
b. Genetically determined abnormal axial inclination of the maxillary central incisors :- Milne and Cleall indicated that if the tooth bud develops with a
more vertical axial inclination, the tooth would assume a more vertical position after eruption
c. Variation in morphology of max central incisors
Nicol - difference in crown root angulation in div 2 cases
Robertson & Hilton - crowns of U1 thinner labiolingually in Div 2
d. Forward tipping of maxillary posterior segment :-
Swann showed a definite pattern involving the timing of development of max tuberocity & max tooth eruption resulting in mesial tipping of max posterior teeth
Environmental factors
Important role
Early loss of max 2nd deciduous molar
Flush terminal plane – common in deciduous dentition
Persistent finger habit displacing max dentition forward, tip the occlusal balance more towards cl II
May lead to lower lip trap, hyper active mentalis – intern tips U1 more labially
Persistent finger, tongue or lip habits can either result in a cl II malocclusion or accentuate an existing one
So preventing measures if any will be limited to environmental factors only
Diagnosis
Prevalence of malocclusion
The prevalence of malocclusion in north India (Delhi children) age 10-13 years is 45% (44.97%)
class I malocclusion is 26% (25.87%),
class II 15% (15.2%)
class III 3.5%
The prevalence of malocclusion in rural children in Haryana (age group 12-16) is (55%)
Class I malocclusion is (44%)
class II (10%)
class III (0.6%)
bimaxillary protrusion (0.5%)
bilateral mutilations (0.8%)
Definite ethnic trend in prevalence of type of malocclusion from north to south India
For class II
Bangalore & Tiruvanantapuram :- close to 5%
In Delhi & Haryana :-10 – 15 %
Characteristic of Class II malocclusion
1. Maxillary Dental Protrusion
Confused with antero-posterior maxillary excess or midface protrusion
Both conditions are characterized by facial convexity
How to differentiate clinically
Excessive overjet is a reliable feature of this dental malocclusion
Generalized maxillary spacing associated with the protruded maxillary incisors may be noticed
The mandible and mandibular dentition are in a normal anteroposterior position
Cephalometric Presentation
Normal anteroposterior
ANB, SNA, and SNB angle
AO-BO difference
True horizontal anteroposterior position of A and B relative to nasion perpendicular
Normal linear measures of the maxilla and mandible
The mandibular incisors -- normal anteroposterior position relative to the NB line, mandibular plane, and frankfort horizontal
Abnormal values -
for maxillary incisors,
A protrusive position relative to lines NA, SN, and frankfort horizontal
2 . Mesial Drift of the Maxillary First Permanent Molars
This dental class II relationship may be unilateral or bilateral
If no incisor protrusion results in crowding of the maxillary arch caused by the loss of space in the arch perimeter
Maxillary tooth size deficiency lead to spacing –lead to mesial migration of u6
Partial anodontia/ microdontia u2, u4
Because of loss of arch lengh due to mesial migratio of u6 – lead to crowding, impacted u3/ u4
The class II division 2
Have excessive lingual inclination of the maxillary central incisors overlapped on the labial by the maxillary lateral incisors
In some cases, both the central and the lateral incisors are lingually inclined and the canines overlap the lateral incisors on the labial
a The central incisors are tipped lingually, the laterals are in labio-version or normally inclined
b All four incisors are tipped lingually and the canines are in mesiolabioversion
c Linguoversion of all six anterior teeth
d Mixed type of frontal malposition, with lingually inclined incisors on one side
Deep overbite and minimal overjet
In cases with extreme overbite, the incisal edges of the lower incisors may contact the soft tissues of the palate
In a few class ii division 2 cases, the mandibular labial gingival tissues may be also traumatized
two distinct occlusal levels,
supra occlusion for the anterior teeth
relative infra occlusion for the posterior segments
An exaggerated curve of Spee may be present in the mandibular arch with extrusion of the mandibular incisors (Strang 1958)
Shape and relationships of the dental arches in Class II cases
Frolich evaluated the dental arch form during the transitional dentition of children with Class II malocclusions who did not undergo orthodontic treatment
divided into four subgroups:
Class II Division 2
Class II borderline between Division1 & 2
Class II Division 1 with a "V' shaped maxillary arch
Class II Division 1 with flaring and spacing of the maxillary incisors
No appreciable differences were present between normal and Class II individuals in absolute arch length and width
Anterior arch length was found to increase markedly during the transition period for all Class II types, except the Division 2 group
Overbite and overjet increased in the untreated Class II Division 1 cases and only excessive overbite increased in the Division 2 cases
Frolich found the shape of the mandibular dental arch to be very similar in all four categories of Class II malocclusion, but the maxillary dental arch was wider in the Division 2 cases
Clinical significance
As a result, it is very difficult to distinguish and predict the ultimate shape of the dental arch before the eruption of the permanent incisors
It has also been established that the anteroposterior relationship of the dental arches in untreated Class II cases, whether in the deciduous, mixed, or permanent dentitions, did not improve with age (Bishara 1988)
Transverse dental arch relationship in Class II Division 1 patients
Bishara and coworkers (1996) evaluated the changes in the dental arch width and length from the deciduous to the mixed and permanent dentitions
The differences between the measurements of maxillary and mandibular intermolar arch widths were greater in the normal subjects than in subjects with Class II Division 1 malocclusions.
The presence of this relative constriction of the maxillary arch, when related to the mandibular arch in Class II malocclusions, is expressed from the earlier stages of dental arch development
Clinical significance
These trends continue in the mixed and early permanent dentitions and do not self-correct without treatment
Therefore, if there is a discrepancy in the transverse relationship, it should be corrected together with the anteroposterior discrepancy
Skeletal Characteristics of Class II Malocclusions
In general, Class II cases with anteroposterior skeletal discrepancies are characterized by a large ANB angle and Wits Appraisal, reflecting the malrelationship between the maxilla and mandible
The anteroposterior skeletal discrepancies may also be accompanied by a vertical discrepancy, for example, a relatively long or short anterior face
Skeletal discrepancies associated with Class II malocclusions have been termed skeletal Class II relationships
This term indicates that the Class II malocclusion is one resulting from an anteroposterior disproportion in size or discrepancy in position of the jaws rather than malposition of the teeth relative to the jaws
Skeletal class II relationships often are associated with class II dental malocclusions
Natural dental compensation can be observed in the presence of the skeletal discrepancy – dental discrepancy less severe than the skeletal discrepancy
Most often as protrusive mandibular incisors
Less frequently as retrusive maxillary incisors
Maxillary dental arch that is more narrow or constricted than normal because it is in occlusion with a narrower part of the mandibular dental arch
This transverse dental compensation is characterized further by mesio-lingual rotation of the maxillary first molars
Mandibular Deficiency
A skeletal class II relationship resulting from a mandible that is small or retruded relative to the maxilla is termed a mandibular deficiency
Characterized by
normal nasolabial angle,
Relative protrusion of the maxillary anterior teeth and
Relative deficiency of the chin caused by the small size or retruded position of the mandible
A pronounced labiomental fold
Lower lip trap
Resulting in lip incompetence
The consequence - further protrusion of the maxillary incisors
Inadequate vertical support for the maxillary Incisors - overeruption of these incisors
Cephalometric analysis – downward and backward rotation of the mandible caused by the small size of the ramus and body of the mandible
Decreased posterior facial height
A steeper mandibular plane angle
An increased ANB angle
Normal SNA , decreased SNB angle
Normal position of point A but a posterior position of point B relative to nasion perpendicular
Retrusion of a normal-sized mandible
The cranial base angle, defined by points nasion, sella,and basion, often is more obtuse --- glenoid fossa in a relatively posterior position
The distinguishing characteristics –
Normal size of the mandibular ramus and body
Normal lower face height in spite of the anteroposterior discrepancy between the maxilla and mandible
Maxillary Excess
Maxillary excess may present as overdevelopment in the vertical or anteroposterior dimension or both
vertical maxillary excess:-more localized to the posterior area, associated with the maxillary posterior teeth being in an inferior position with a normal vertical position of the incisors
Presentation usually as :- anterior open bite with a normal vertical display of the maxillary incisors relative to the upper lip both in repose and upon smiling
Vertical maxillary excess - overall excess
No anterior open bite, but an excessive vertical display of the maxillary incisors relative to the upper lip in repose as well as a gummy smile
In either of these two presentations, the mandible is rotated downward and posteriorly (clockwise rotation), resulting in the class ii skeletal relationship
Maxillary excess in the anteroposterior dimension or midface protrusion
Can be easily confused with maxillary dental protrusion
Both conditions exhibit facial skeletal convexity with a normal anteroposterior position of the mandible
But maxillary anteroposterior excess characterized by a protrusion of the entire midface, including the nose and infraorbital area as well as the upper lip
Cephalometric features of anteroposterior maxillary excess
Increased ANB angle and A-B difference
Increased facial convexity
SNA angle increased, SNB angle is normal
A point is anterior, and B point is normal
Anteroposterior maxillary length increased
Anteroposterior mandibular length normal
Anteroposterior dental compensation in the form of
Mandibular incisor protrusion and transverse dental compensation in the form of maxillary constriction
Combination of Mandibular Deficiency and Maxillary Excess
It is likely that most patients with skeletal class II problems have a combination of mandibular deficiency and maxillary excess.
Maj and coworkers concluded that the skeletal differences were not due to an abnormal development in the size of any specific part, but rather were the result of an abnormal relationship between the parts, that is, the result of variations in the position of the skeletal structures, in the direction of the discrepancy
Cephalometric characteristics of the Class II Division 2 malocclusion
Wallis compared Class II Division 2 , Class I and Class II Division 1 individuals and found that the posterior cranial base was larger in Division 2 cases
He also noted that the mandibular found in a "typical" Division 2 case has relatively more acute gonial and mandibular plane angles, shorter lower anterior face height, and excessive overbite
Hedges concluded that the only consistent cephalometric finding was the lingual axial inclination of the maxillary central incisors
Perioral Functional Characteristics of Class II Malocclusions
Abnormal muscular patterns may be associated with either type of Class II malocclusions
As in Class II Division I, the increased overjet may allow the lower lip to rest between the maxillary and mandibular incisors maintaining or accentuating the overjet.
During swallowing
An abnormal mentalis muscle activity and aberrant buccinator activity, together with compensatory tongue function and position, could cause changes in dentofacial structures
Such as constriction of the maxillary posterior segments, protrusion and spacing of the maxillary incisors, and abnormal inclination of the mandibular incisors
In Class II Division 2 individuals, the orbicularis oris and mentalis muscles are often well developed and active
The lingual inclination of the maxillary incisors may accentuate the appearance of the lower "lip curl" associated wit the vertical over closure
In addition, the combined effects of the hyperactive mentalis muscle and the reduced vertical height accentuates the chin prominence
Clinical significance
In summary, describing the skeletal discrepancies accompanying Class II Division l or 2 malocclusions as being a "skeletal Class II malrelationship“ is a diagnostic oversimplification and of limited value in treatment planning
This is because the mandible can either be in a normal or retruded relationship to the maxilla, and in turn the maxilla may be either normal or in a protruded relationship to the mandible
As a result, the clinician should evaluate and diagnose, in each individual patient, the occlusal relationships, the anteroposterior and vertical skeletal discrepancies, the soft tissue facial relationships, as well as the presence of any abnormal function for appropriate treatment planning
CONCLUSION
• Class II malocclusions can be treated by several means, according to the characteristics associate with the problem, such as anteroposterior discrepancy, age, and patient compliance. Methods include extraoral appliances functional appliances, and fixed appliances associated with Class II inter maxillary elastics, extraction and surgery..
• The clinician should evaluate and diagnose, in each individual patient, the occlusal relationships, the anteroposterior and vertical skeletal discrepancies, the soft tissue facial relationships, as well as the presence of any abnormal function for appropriate management of class II malocclusion
BIBLIOGRAPHY
1. Robert E. Moyers- Handbook of Orthodontics- 4th ed2. Salzmann. J. A- Orthodontics in daily practice- 4th ed3. William R. Proffit- Contemporary Orthodontics- 3rd ed4. T. M. Graber- Orthodontics- Principles and practice5. T. C. White, J. H. Gardiner, B. C. Leighton- Orthodontics for dental students.6. Shafer, Hine and Levy- A text book of oral pathology- 4th ed7. Craig CE. The skeletal patterns characteristic of Class I and Class II, Division 1
malocclusions in norma lateralis. Angle Orthod. 1951;21:44–56.8. Hitchcock HP. A cephalometric description of Class II division 1 malocclusion. Am J
Orthod. 1973;63:414–423.9. McNamara JA Jr. Components of Class II malocclusion in children 8–10 years of age.
Angle Orthod. 1981;51:177– 202.10. Athanasios E Athanasiou - Orthodontic cephalometry 11. McLaughlin , Bennet - Orthodontic Management of the Dentition with the Preadjusted
appliance12. Angle EH. Classification of malocclusion. Dental Cosmos. 1899;41:248–264.13. Hitchcock HP. A cephalometric distinction of Class II division 2 malocclusion. Am J
Orthod. 976;69:123–13014. Henry RG. A classification of Class II division 1 malocclusion. Angle Orthod.
1957;27:83–92.
Top Related