Abstract
BackgroundThe incisal guidance angle (IGA) is related to temporomandibular joint (TMJ), and changes to the IGA are often involved in the prosthetic and orthodontic treatment of anterior teeth. However, the influence of incisal guidance on the growth, development and remodelling of the TMJ is not yet clear. The aim of this study was to investigate age-related morphological differences in the TMJ in subjects with different IGAs.MethodsCone-beam computed tomography (CBCT) images of 274 patients were included (group 1, IGA < 45°; group 2, 45° ≤ IGA ≤ 60°; group 3, IGA > 60°). Each group was then divided into 4 age groups (group a, 6–12 years; group b, 13–16 years; group c, 17–25 years; group d, 26–33 years). TMJ morphology was assessed by linear measurements, angular measurements, and subjective evaluations. The IGA and occlusal plane angle were also measured.ResultsAnterior inclination of condyle (AIC) increased with age in the three IGA groups but decreased from 17 years onward in group 2 (P < 0.05). In the age groups analysis, the AIC in group 1 was smaller than that in group 3 but larger than that in group 2 (P > 0.05). Articular eminence inclination (AEI) decreased with age in group 1 (P = 0.027) but increased with age in group 3 (P = 0.053). The AEI in group 2 was larger than that in group 1 at 17–25 years (P = 0.046), and it was larger in group 3 than in group 1 at 26–33 years (P = 0.047). The IGA had a weak correlation with AEI (P < 0.05).ConclusionThe articular fossa of patients with shallower incisal guidance changed to a flatter shape with age, whereas the condylar anterior slope and articular eminence of patients with steeper incisal guidance changed towards a steeper alignment. There was a correlation between IGA and TMJ shape.
Highlights
The incisal guidance angle (IGA) is related to temporomandibular joint (TMJ), and changes to the IGA are often involved in the prosthetic and orthodontic treatment of anterior teeth
Li et al BMC Oral Health (2021) 21:380 examined the differences in the temporomandibular joint related to diverse malocclusions, and confirmed that the morphological structure and positional relationship between the condyle and articular fossa may be different in patients with various types of malocclusion [3, 4]
These two malocclusion deformities result in abnormal disc pressure that may affect the anterior slope of the condyle and articular eminence
Summary
The incisal guidance angle (IGA) is related to temporomandibular joint (TMJ), and changes to the IGA are often involved in the prosthetic and orthodontic treatment of anterior teeth. Occlusal factors, including incisal guidance, are often altered during prosthetic and orthodontic treatment, such as occlusal reconstruction and restorative treatment of anterior teeth. Shallow anterior guidance guides the mandible to move forward excessively when the mandible is in forward movement, while steep anterior guidance may hinder mandibular advancement. These two malocclusion deformities result in abnormal disc pressure that may affect the anterior slope of the condyle and articular eminence
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