Author Topic: Components of adult Class III open-bite malocclusion  (Read 2068 times)

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Components of adult Class III open-bite malocclusion
« on: July 11, 2013, 04:45:53 PM »
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(1) the posterior maxilla exhibited vertical excess in the OB group; (2) the maxillary occlusal plane was less steep in the OB group; (3) the mandibular occlusal plane was more steep in the OB group; (4) the gonial angle was higher in the OB group; (5) the mandibular plane angle was higher in the OB group; (6) the mandibular ramus was positioned in a more downward and backward location in the OB group; (7) the total anterior facial height and lower facial height were increased in the OB group; (8) the vertical height of the anterior maxilla was increased in the OB group; and (9) the mandible was less protrusive in the OB group. No significant intergroup differences were noted in the cranial base, the anteroposterior position of the maxilla or the upper and lower incisors, the palatal plane, posterior facial height, mandibular ramus height, or mandibular body height. The results of this analysis indicate that the average Class Ill open-bite malocclusion is characterized by aberrations in both the maxilla and the mandible. Surgical therapy may, therefore, require intervention in both jaws to correct this deformity successfully.

all of these points make sense to me except (6). why would the ramus be positioned downward and backward? can the position of the maxilla displace the ramus?

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Re: Components of adult Class III open-bite malocclusion
« Reply #1 on: July 11, 2013, 05:02:50 PM »
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Although patients with skeletal open-bite defor- mities exhibit a spectrum of skeletal, dental, neu- romuscular, and esthetic abnormalities
well, fuck. I wonder what, if anything, can be done about this.

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Their studies showed no significant difference in the maxillary occlusal plane angle; however, the man- dibular occlusal plane angle was significantly greater in all open-bite cases than in controls. This finding sug- gests that the open-bite deformity arises below the maxillary dentition.
Bizarre. Why then, is posterior impaction the movement used to close the open bite?

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Sassouni and Nanda?? found that the mandibular condyle was located in a superior position, thereby in- directly decreasing effective ramus height and thus producing a larger mandibular plane angle. These findings suggest that the high mandibular plane angle consistently found in open-bite patients is due to an effectively shorter mandibular ramus and an opening rotation of the mandibular ramus.
Well there it is. seems repositioning the condyles and, if necessary, increasing the overall vertical length of the ramus would be more effective. whether that form of treatment exists, i dont know

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An increase in maxillary posterior dentoalveolar height is another commonly cited factor in open-bite Cases,?.:?4.:??.4:?.15 However, Nahoum and co-workers?? did not find any significant difference in posterior max-illary dentoalveolar height between their open-bite and normal samples. Therefore, no consensus exists as to the relationship of posterior dentoalveolar hyperplasia to open bite.

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One of the most distinguishing features of the skeletal open-bite population is that the total anterior facial height is greater than that in a normal popula- tion ,T.:i4.:iT,. I I .4X-.32 Most studies show that this in- crease occurs primarily in the lower anterior facial height or in the area below the anterior nasal spine? .? rather than in the upper an-
terior facial height, which remains normal??J5,?? or is shorter in open-bite patients.??,This indicates that most of the deformity occurs below the level of the palate.
So no elongation of the upper midface then...

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Re: Components of adult Class III open-bite malocclusion
« Reply #2 on: July 11, 2013, 05:44:24 PM »
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After examining the various aspects of the Class III open-bite malocclusion, one can clearly see that this deformity is not confined to one particular anatomic structure but, instead, involves various aspects of both the maxilla and the mandible. It is not surprising, there- fore, that treatment may involve surgery in both jaws. The treatment that would correct most of the open-bite problems in the Class III open-bite deformity would include surgical intrusion of the posterior maxilla via either segmental or total maxillary surgery. This would
correct both the posterior maxillary dentoalveolar hy- perplasia and the aberrant maxillary occlusal plane an-
gle. Posterior maxillary intrusion also would allow the mandible to autorotate ?closed, ? partially correcting
the high mandibular plane angle and decreasing the lower anterior facial height, while at the same time
worsening the mandibular protrusion. However, this treatment would now allow the mandible to be retruded via a mandibular ramus osteotomy without stretching the masticatory musculature (Fig. 3, C).
So that's why. super disappointing.

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As Carlson and Schneiderman? have demonstrated very effectively, in the continuing struggle between the soft and hard tissues of an altered homeostasis, the soft tissues will certainly win.
This entire process summed up in a single sentence.

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Re: Components of adult Class III open-bite malocclusion
« Reply #3 on: July 11, 2013, 05:46:59 PM »
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As Carlson and Schneiderman? have demonstrated very effectively, in the continuing struggle between the soft and hard tissues of an altered homeostasis, the soft tissues will certainly win

what does that mean?  ???
Chopsticks > Spoons

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Re: Components of adult Class III open-bite malocclusion
« Reply #4 on: July 11, 2013, 05:48:31 PM »
what does that mean?  ???
meaning soft tissue will always dictate size & positioning of the hard tissue. moving the hard tissue in a position that combats the soft tissue is a losing proposition, and guaranteed relapse