Stability of Surgical versus Non-surgical Management of Anterior Open Bite Dr. PETER SHAPIRO Dr. Shapiro's excellent paper was based on many research studies. His bibliography was quite extensive and is available through the CDABO offices. He has found it is important not to pigeon hole patients. It is enlightening to him to find patients with a steep mandibular plane angle and large adenoidal masses, etc., that do not have open bites: and patients with normal facial patterns and measurements that have strong open bites. He defined open bite as it was used in his presentation and in the research papers he cited as: 1.) Open bite - no overlap or contact of incisors as viewed cephalometrically and clinically. 2.) Overlap (sometimes called open bite tendency) - incisors do not touch as viewed cephalometrically or clinically. Incisors touch when the mandible is advanced. 3.) Contact - incisors touch in occlusion He personally feels that if the teeth do not touch each other, it is an open bite, but this overlap category is important in open bite research. Overlap was judged by drawing a line down the occlusal plane bisecting buccal cusp tips in occlusion. If incisors touched this line it was overlap category. Stability of Open bite Treatment (non-surgical) Lopez-Gavito, G, Wallen, T, Little, R and Joondeph, D. Anterior open-bite malocclusion: A longitudinal 10-year post retention evaluation of orthodontically treated patients. Am J Orthod 87:175-186, 1985. A study that looked at a post retention sample at the University of Washington, in which the patients were a minimum of nine years post retention and 3mm of open bite or greater. It was found that 35% of open bites treated relapsed to a significant open bite of 3mm or more. They found no predictors for relapse; steep mandibular plane angle or any other single parameter of dentofacial form proved to be significant in stability or relapse of open bite treatment. One third of open bite treatment will relapse and two thirds will remain reasonably stable. This percentage seems to be found in most research and can be used clinically in counseling patients and dentists. Zuroff, J. Orthodontic treatment of anterior open-bite malocclusion: Stability ten years post-retention. MSD Thesis, University of Washington, Seattle, 1990. This study includes 64 patients; 10 years post retention in three categories: 1. 24 patients with contact 2. 25 patient with overlap 3. 15 patients with open bite It was found that: 1. Generally if patients start out with contact they will end up that way. 2. Relapse was mostly due to lower incisor crowding and setting back but not erupting. 3. All patients had overlap at end of treatment in all categories. He felt that overlap is pretty good because mandible can be advanced to touch incisors. 4. Even the open bite patients were good; six had contact, nine had overlap and none had open bite. This is an encouraging study for open bite treatment showing contact or at least overlap in all long term retention. Except for the fact that orthodontists consider it relapse when incisors do not touch in occlusion, as was the case in all the overlap cases. Katsaros, C and Berg, R. Anterior open bite malocclusion: a follow-up study of orthodontic treatment effects. Eur J Orthod 15:273-280, 1993. Found 75% successfully treated open bite cases. To be successful 2 incisors had to touch when mandible advanced. So again, not correct overbite and overjet in occlusion when CO/CR coincide. Crib Therapy in Conjunction with Open bite Treatment (non-surgical) Juang, G, Justus, R, Kennedy, D and Kokich, V. Stability of anterior open bite treated with crib therapy. Angle Orthod 60:17-24, 1990. 1. Found 0% of non-growing patients showed relapse, and 17% of growing patients showed relapse. 2. Crib therapy seemed to help a lot 3. Must be in mouth at least one year 4. Thumb habit correction is a great help 5. Changing tongue activity and posture is goal 6. The 87% successfully treated cases include overlap and contact cases. Stability of Open bite Treatment (surgical) Denison, T, Kokich, V and Shapiro, P. Stability of maxillary surgery in open bite versus non-open bite malocclusion. Angle Orthod 59:5-10, 1989. This study included 66 patients - all were non-growing and all had maxillary surgery for: 1. Excessive face heights 2. High smile line 3. Anterior open bite a) 28 had open bite b) 24 had over lap - no contact c) 14 had contact (all of these patient had vertical maxillary excess or HSL) Results: 1. 83% of overlap cases were stable 2. 100% of contact cases were stable 3. 57% of open bite cases were stable - either contact or overlap Examining the Effect on Stability of Extruding Maxillary Incisors or not Prior to Maxillary Surgery Lo, F and Shapiro, P. The effect of presurgical incisor extrusion on stability of anterior open bite malocclusion treated with orthognathic surgery. Int J Adult Orthod Orthognath Surg 13:23-34, 1998. Group #1: 21 patients, maxillary surgery, incisors were not extruded. Group #2: 19 patients; arch leveled and incisors extruded prior to maxillary surgery. Results: At least one year after end of treatment they found no difference between groups. Conclusion: A moderate amount (3mm or less) of upper incisor extrusion to level the arch is stable long term. Etiology of Open bite 1. Growth pattern - a complicating fact but not main etiology 2. Nasal airway obstruction 3. Digit sucking 4. Abnormal tongue posture/function. Heavy intermittent forces such as swallowing not as causative as light continuous forces such as posturing tongue forward between the teeth. General Observations: 1. Effect of tonsillectomy and adenoidectomy not predictable 2. Myofunctional therapy may not help, but will not hurt 3. Crib therapy seems to be effective 4. Open bite is hardest problem in orthodontics - overall 30% of open bites will return 5. Partial glossectomy - no clear evidence of increase in long term stability 6. Molar and incisor eruption seem to occur in harmony. In open bite cases that relapse there seems to be more molar eruption than incisor eruption. 7. Open bite relapse occurs in the first 1-2 years after braces have been removed. You will know in the first year usually if there is a problem. 8. Dr. Greg Huang in his new paper found that 80% of open bites whether done with surgery or with orthodontics alone will have reasonable stability, that is, will have contact or overlap. 9. Dr. Shapiro feels confident in treating open bite, as he knows 70-80% will be corrected and retained reasonably well.