Only severe malocclusion correlates with mastication deficiency

•Subjects with moderate malocclusion can adapt to masticate demanding foods.•Severe malocclusion as shown by subjects relevant to orthognathic surgery correlates with mastication deficiency.•A clear decreased in oral quality of life is only observed in severe malocclusion subjects.

ObjectivesThe relation between level of dentofacial deformity and extent of masticatory deficiency was studied.DesignThree groups of human young adults were formed: (i) subjects needing orthodontics plus orthognathic surgery (SevDFD, n = 18), (ii) subjects needing orthodontic treatment only (ModDFD, n = 12), and (iii) subjects needing no treatment (NoDFD, n = 12). For mastication tests, carrot boluses were collected at the deglutition time. Bolus particle size range was expressed as d50 value, which was compared with the Masticatory Normative Indicator (MNI). Index of treatment need (IOTN), global oral health assessment index (GOHAI) and chewing kinematic characteristics were also recorded. We used a general linear model univariate procedure followed by a Student-Newman-Keuls test.ResultsAll the SevDFD subjects showed impaired mastication with MNI above the normal limit (d50 mean = 7.23 mm). All the ModDFD subjects but one were below this limit (d50 mean = 2.54 mm), and so could adapt to a low level of masticatory impairment as also indicated by kinematics. IOTN indicated a treatment need for ModDFD (3.7 ± 0.5) and SevDFD (4.3 ± 0.6) groups, while GOHAI values were unsatisfactory only for SevDFD (42.6 ± 9.2 vs. 55.3 ± 1.9).ConclusionsOur findings emphasize the need for an objective evaluation of masticatory function to discern truly deficient mastication from mild impairment allowing satisfactory adaptation of the function. However, malocclusions are known to worsen with time justifying thus their corrections as early as possible.