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Journal of Indian Society of Pedodontics and Preventive Dentistry Official publication of Indian Society of Pedodontics and Preventive Dentistry
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Year : 2009  |  Volume : 27  |  Issue : 4  |  Page : 202-204

The effect of posterior bite-plane on dentoskeletal changes in skeletal open-bite malocclusion

1 Department of Orthodontics, Islamic Azad University, Tehran, Iran
2 Department of Orthodontics, Tehran University of Medical Sciences, Tehran, Iran
3 Private Practice, Tehran, Iran

Date of Web Publication14-Nov-2009

Correspondence Address:
S Emami Meibodi
Apartment 8, No.5, Jalinus Alley, Yarmohammadi Alley, Kolahdouz St., Shariati Ave., Tehran
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-4388.57653

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With regard to the vertical problem of skeletal open-bite malocclusion, this study was undertaken to evaluate the effect of upper posterior bite-plane on the dentoskeletal changes of skeletal open-bite malocclusion. The material consisted of 23 patients, with skeletal open-bite in mixed dentition period. The patients were treated by upper removable posterior bite plane appliance. Before and after treatment lateral cephalogram were obtained. Certain angular and linear variables were measured. The pre-treatment and post-treatment measurements were compared using paired t-test to evaluate the significance of the results. There were significant changes in vertical incisor overlap following treatment with upper posterior bite plane. Increase of PFH, Jaraback index, UAFH/LAFH ratio were significant .There was significant decrease in SN-MP angle. The dentoalveolar heights of the upper and lower anterior segment were increased as well as the distance of the lower molars to mandibular plan. Only the maxillary first molar height did not change.

Keywords: Mixed dentition period, posterior bite-plane, skeletal open-bite

How to cite this article:
Meibodi S E, Fatahi Meybodi S, Samadi A H. The effect of posterior bite-plane on dentoskeletal changes in skeletal open-bite malocclusion. J Indian Soc Pedod Prev Dent 2009;27:202-4

How to cite this URL:
Meibodi S E, Fatahi Meybodi S, Samadi A H. The effect of posterior bite-plane on dentoskeletal changes in skeletal open-bite malocclusion. J Indian Soc Pedod Prev Dent [serial online] 2009 [cited 2022 Aug 17];27:202-4. Available from: http://www.jisppd.com/text.asp?2009/27/4/202/57653

   Introduction Top

Skeletal open-bite is one of the most difficult malocclusions to treat. The morphologic pattern usually consists of excessive vertical height in maxillary dentoalveolar portion, [1] and the absence of over-bite in anterior segment of dental arches. [2] Kelly et al have reported the prevalence of this malocclusion in 3.5% of white American children and 16.5% of African-Americans, [3] while a prevalence of 3.5% in patients aged 8 to 17 is reported by Proffit et al. [4] In an investigation it was shown that among patients suffering from skeletal open-bite, 41% had a Cl II Div 1 malocclusion [5] which was created due to improper growth pattern, inheritance or oral habits. [6],[7] If left untreated, several unfavorable sequela would be encountered such as posterior cross-bite, anterior facial height excess and facial disproportion, and lip incompetency [8],[9],[10],[11],[12],[13],[14],[15] and orthodontic treatment could become so difficult that orthognathic surgery would be inevitable.

Vertical chin-cup, high pull head-gear, vertical elastics, functional appliances and skeletal anchorage have been proposed for treatment. [8],[9],[10],[11],[12] Among the treatment protocols is growth modification, recruitment of growth remained, which consists of early treatment of vertical dimension during mixed dentition period by restraining vertical alveolar growth with a functional appliance. Posterior bite plane, which could be considered a simple functional appliance, could be used for this purpose. Some believe that forward and upward rotation of mandible achieved by this appliance is beyond that of fixed orthodontic appliances. [16],[17],[18] Regarding controversies existing about this appliance, this study was undertaken to evaluate the effect of posterior bite plane on dentoskeletal characteristics in skeletal open-bite.

   Materials and Methods Top

Twenty three patients (13 girls and 10 boys), aged 9.5 ± 1 years, who were referred to an academic center and a private clinic in Tehran were selected based on the following criteria: mixed dentition period, vertical growth pattern with SN-MP > 36°, anterior open-bite > 1 mm, lack of history of orthodontic treatment, trauma and dentofacial syndromes. All the patients were treated with a posterior bite plane, which consisted of a simple removable maxillary Hawley appliance with occlusal acrylic plate from distal of first permanent molar to mesial of first deciduous molar that vertically exceeded the freeway space by 2 mm. The minimum treatment period was 8 months. The pre- and post-treatment lateral cephalograms were obtained, traced and the following measurements were done with an accuracy of 0.5 mm for linear measurements or 0.5° for angular measurements [Figure 1]: SN-MP, AFH, PFH, Jaraback index, UAFH/LAFH. In order to evaluate the vertical position of dentition, the distance of central incisor edge (1 for upper incisor, /1 for lower incisor) and mesial cusp of first permanent molar (6 for upper molar, /6 for lower molar) to palatal plan (PP) or mandibular plan (MP) for respective jaw were measured. All the parameters were re-measured for the 10 randomly selected cases; since the difference between 2 was not significant, the first measurements were considered for statistical analysis by paired t-test.

   Results Top

SN-MP was significantly decreased, where as PFH, Jaraback index and UAFH/LAFH were significantly increased; change in AFH was insignificant [Table 1].

Regarding vertical dimension of dentition, all the measurements increased significantly unless those related to upper molar (6-PP) where the changes were insignificant [Table 2].

   Discussion Top

This study showed that the posterior bite plane as a removable appliance caused the SN-MP to decrease significantly; since AFH had not changed while PFH increased, it seems that the appliance made the soft tissue and muscles to stretch, induced the growth in posterior region and mandibular rotation upwardly. Significant increase in UAFH/LAFH confirms anterior rotation of mandible and decrease of LAFH.

Significant increase in mandibular and maxillary anterior dentoalveolar height indicates that one of the reasons that caused the open-bite to close was the eruption of anterior teeth. In the upper first molar region, dentoalveolar height did not undergo any increase (and even slightly decreased); the conclusion is that the posterior-bite plane inhibited the eruption of upper molars and dentoalveolar growth, which are among the most important factors in vertical growth. As for lower first molar, the dentoalveolar height increased; although it may seem the contrary, the appliance did not inhibit its eruption.

Stellzig [17] found that in open-bite patients, bite block caused the vertical growth to decrease and Jaraback index to increase. He declared that bite block would stimulate the masticator muscles consistently, and produce an intrusive force against the posterior segment. In our study, decrease in SN-MP and increase in Jaraback index also indicate vertical growth inhibition; but dentoalveolar height increased in mandible while remaining constant in maxilla.

Kuster [18] declared that bite block would produce intrusive forces on upper and lower molars; by means of electromyography he observed increased activity in the temporalis and masseter muscles in the beginning of the treatment, which remained constant thereafter. He considered the eruption of anterior segment as the cause of open-bite closure, the same observation we had encountered.

Mavropoulos [19] studied the effect of bite plane in growing mice and declared that the major mechanism of open-bite closure was anterior rotation in mandible, posterior segment intrusion and increase in mandibular growth. He also stated that the functional appliance displaced the mandible, stretched the surrounding soft tissue and exerted forces to dentoskeletal structures directly or indirectly. He believed that the appliances that open the bite can influence the mandibular morphology and observed changes in mandibular plan, occlusal plan and coronoid process length.

   Conclusion Top

The results of this study revealed that with posterior bite plane therapy during mixed dentition period in patients suffering from skeletal open-bite, one could inhibit the posterior maxilla to grow vertically and with anterior mandibular rotation due to growth in posterior face, disharmony would be relieved, saving patient from future complex orthodontic treatment or even orthognathic surgery.

   References Top

1.Subtelny JD, Sakuda M. Open-bite: Diagnosis and treatment. Am J Orthod 1964;50:337-58.  Back to cited text no. 1      
2.Schendel SA, Eisenfeld J, Bell WH, Epker BN, Mishelevich DJ. The long face syndrome: Vertical maxillary excess. Am J Orthod 1976;70:398-408.   Back to cited text no. 2      
3.Kelly JE, Sanchez M, Van Kirk LE. An assessment of the occlusion of teeth of children 6-11 Years [US Public Health Service DHEW Pub No 130]. Washington, DC: National Center for Health Statistics; 1973. p. 3.   Back to cited text no. 3      
4.Proffit WR, Fields HW, Moray LJ. Prevalence of malocclusion and orthodontic treatment need in the United State estimate from the N-HANES III survey. Int J Adult Orthod Orthognath Surg 1988;13:97-106.  Back to cited text no. 4      
5.Ngan P, Fields HW. Open bite: A review of etiology and management. Pediatr Dent 1997;19:91-8.  Back to cited text no. 5      
6.Warren JJ, Bishara SM. Duration of nutritive and nonnutritive sucking behaviors and their effects on the dental arches in the primary dentition. Am J Orthod Dentofac Orthop 2002;121:347-56.  Back to cited text no. 6      
7.Nielsen IL. Vertical malocclusions: Etiology, development, diagnosis, and some aspects of treatment. Angle Orthod 1991;61:247-60.   Back to cited text no. 7      
8.Sankey WL, Buschang PH, English J, Owen AH. Early treatment of vertical skeletal dysplasia: The hyperdivergent phenotype. Am J Orthod Dentofac Orthop 2000;118:317-27.  Back to cited text no. 8      
9.Basciftci FA, Karaman AI. Effects of a modified acrylic bonded rapid maxillary expansion appliance and vertical chin cap on dentofacial structures. Angle Orthod 2002;72:61-71.   Back to cited text no. 9      
10.Frδnkel R, Frδnkel C. A functional approach to treatment of skeletal open bite. Am J Orthod 1983;84:54-68.  Back to cited text no. 10      
11.Sherwood KH, Nurchg JG, Thompson WJ. Closing anterior open bites by intruding molars with titanium miniplate anchorage. Am J Orthod Dentofac Orthop 2002;122:593-600.   Back to cited text no. 11      
12.Yao CC, Wu CB, Wu HY, Kok SH, Chang HF, Chen YJ. Intrusion of the overerupted upper left first and second molars by mini-implants with partial-fixed orthodontic appliances: A case report. Angle Orthod 2004;74:501-7.  Back to cited text no. 12      
13.Isηan HN, Akkaya S, Elηin K. The effect of spring-loaded posterior bite block on the maxillo-facial morphology. Eur J Orthod 1992;14:54-60.  Back to cited text no. 13      
14.Arat M, Iseri H. Orthodontic and orthopedics approach in the treatment of skeletal open bite. Eur J Orthod 1992;14:207-15.   Back to cited text no. 14      
15.Weinbach JR, Smith RJ. Cephalometric changes during treatment with the open bite Bionator. Am J Orthod Dentofac Orthop 1992;101:367-74.  Back to cited text no. 15      
16.Cozza P, Mucedero M. Baccetti T, Franchi L. Early orthodontic treatment of skeletal open bite malocclusion. Angle Orthod 2004;75:707-13.  Back to cited text no. 16      
17.Stellzig A, Steegmayer-Gilde G, Basdara EK. Elastic activator for treatment of open bite. Br J Orthod 1999:26:89-92.  Back to cited text no. 17      
18.Kuster R, Ingervall B. The effect treatment of skeletal open bite with two types of bite block. Eur J Orthod 1992;14:489-99.   Back to cited text no. 18      
19.Mavropoulos A, Bresin A, Slaveros K. Morphometric Analysis of the mandible in growing rats with different masticatory functional demands: Adaptation to an upper posterior bite block. Eur J Oral Sci 2004;112:259-66.  Back to cited text no. 19      


  [Figure 1]

  [Table 1], [Table 2]

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