Title Patients With Posterior Cross-Bite Have Significantly Reduced Maximum Bite Force, Contact Area, Food Intake Ability, And Mixing Ability Incidence
Clinical Question Do individuals with posterior cross-bite have decreased masticatory function compared to normal?
Clinical Bottom Line Patients with posterior cross-bite malocclusion have significantly reduced bite force, contact area, food intake ability, and Mixing Ability Incidence (MAI). This is supported by a case control study that measured two static objective measurements (max bite force and contact area), a dynamic objective measurement (MAI), and one subjective measurement (food intake ability). The study evaluated masticatory function for four different groups: normal occlusion, posterior cross-bite, anterior openbite and lastly, patients with posterior cross-bite and anterior openbite.
Best Evidence  
PubMed ID Author / Year Patient Group Study type
(level of evidence)
25185505Choi/201584 patients with 63 nonsaggital and 21 normal occlusion Case Control Study
Key resultsCompared to normal occlusion, posterior cross-bite patients had significantly reduced maximum bite force, contact area, Mixing Ability Index (MAI) and food intake ability (P < 0.001). There was a strong correlation between the maximum bite force and the contact area (r = 0.99, P < 0.001). The MAI and the maximum bite force showed a significant but weak correlation (r = 0.24, P < 0.05); correlations were moderate between the maximum bite force and the food intake ability and between the MAI and the food intake ability (r = 0.358, r = 0.383, respectively; P < 0.01).
Evidence Search Posterior Cross Bite AND Mastication
Comments on
The Evidence
Validity: This study was a case control study where the groups followed set criteria. Normal and malocclusion patients were evaluated with cephalometric analysis. Patients were required to have natural dentition with no missing teeth except for third molars, no facial deformity, normal or marginal cephalometric measurements, no previous history of orthodontic treatment, no significant temporomandibular disorders or symptoms and minimal crowding of less than 3 in each dental arch. This was not a blinded experiment. There was no reported lack of follow-up or difficulty with compliance, and I believe that recall bias was unlikely. There appeared to be no competing interests. Perspective: This study only involved patients that were relatively young and very similar in age (mean age in each group, 22-24 years). I believe that the differences in mastication between posterior cross-bite and normal occlusion could diminish as the patient ages and the muscles of mastication adapt.
Applicability Posterior cross-bites are very common in patients. It is important to inform patients that posterior cross-bites could diminish the potential strength of mastication which could lead to jaw fatigue and other occlusal problems.
Specialty (Orthodontics)
Keywords Posterior cross-bite, mastication, masticatory function
ID# 3178
Date of submission 03/31/2017
E-mail IRANNEZHAD@livemail.uthscsa.edu
Author Mahmoud Irannezhad, MS
Co-author(s) e-mail
Faculty mentor Peter Gakunga, BDS, MS, PhD
Faculty mentor e-mail Gakunga@UTHSCSA.edu
Basic Science Rationale
(Mechanisms that may account for and/or explain the clinical question, i.e. is the answer to the clinical question consistent with basic biological, physical and/or behavioral science principles, laws and research?)
None available
Comments and Evidence-Based Updates on the CAT
None available