The influence of masticatory hypofunction on developing rat craniofacial structure

(a) Landmarks of anthropometric points. Cranial anthropometric points: 1, Internasal point; 2, Nasofrontal point; 3, Lateral nasal point; 4, Orbita point; 5, Zygion point; 6, Frontoparietal point; 7, Squama temporalis point; 8, Occipital point; 9, Tympanic point; 10, Nasomaxillary point. Maxillary anthropometric points: 11, Key ridge point; 12, Zygomatic arc, inferior point; 13, Zygomatic arc, anterior point; 14, Incisive foramen, lateral point; 15, Posterior nasal spine; 16, Prosthion point; 17, Incisive superior alveolar point; 18, U1, incisal point; 19, U1, cervicolabial point; 20, U1, cervicopalatal point; 21, U1, mesial point; 22, U1, distal point; 23, U6, mesial point; 24, U6, mesiobuccal cusp point; 25, U8, distal point; 26, U8, mesiobuccal cusp point. Mandibular anthropometric points: 27, Coronoid point; 28, Coronoid notch point; 29, Condylion point; 30, Gonion point; 31, Gnathion; 32, Mn point; 33, Antegonial incisure; 34, Anterior masseteric line; 35, Menthon point; 36, Mandibular alveolar point; 37, Infradental point; 38, Incisive inferior alveolar point; 39, L1, incisal point; 40, L1, cervicolabial point; 41, L1, cervicolingual point; 42, L1, mesial point; 43, L1, distal point; 44, L6, mesial point; 45, L6, mesiobuccal cusp point; 46, L8, distal point; 47, L8, mesiobuccal cusp point. (b) Anthropometric measurements. Cranial Measurements: 1, Total skull length; 2, Nasal length; 3, Nasal width; 4, Interorbital width; 5, Interzygomatic width; 6, Maximum skull width; 7, Maximum skull height; 8, Upper anterior facial height; 9, Lower anterior facial height; 10, Total anterior facial height. Maxillary measurements: 11, Total maxillary length; 12, Incisive foramen width; 13, Maxillary width; 14, U6 intermolar width; 15, U8 intermolar width; 16, U1 incisor crown height; 17, U6 height; 18, Maxillary posterior arch length; 19, U1, labiolingual distance; 20, U1, mesiodistal distance. Mandibular measurements: 21, Mandibular length I; 22, Mandibular length II; 23, Mandibular length III; 24, Corpus length; 25, Ramus height I; 26, Ramus height II; 27, Ramus height III; 28, Ramus height IV; 29, Corpus height; 30, Mandibular plane angle; 31, Bicoronoidal width; 32, Bicondylar width; 33, Bigonial width; 34, L6 intermolar width; 35, L8 intermolar width; 36, L1, incisor crown height; 37, L6 height; 38, Mandibular posterior arch length; 39, L1, labiolingual distance; 40, L1, mesiodistal distance.

(a) Landmarks of anthropometric points. Cranial anthropometric points: 1, Internasal point; 2, Nasofrontal point; 3, Lateral nasal point; 4, Orbita point; 5, Zygion point; 6, Frontoparietal point; 7, Squama temporalis point; 8, Occipital point; 9, Tympanic point; 10, Nasomaxillary point. Maxillary anthropometric points: 11, Key ridge point; 12, Zygomatic arc, inferior point; 13, Zygomatic arc, anterior point; 14, Incisive foramen, lateral point; 15, Posterior nasal spine; 16, Prosthion point; 17, Incisive superior alveolar point; 18, U1, incisal point; 19, U1, cervicolabial point; 20, U1, cervicopalatal point; 21, U1, mesial point; 22, U1, distal point; 23, U6, mesial point; 24, U6, mesiobuccal cusp point; 25, U8, distal point; 26, U8, mesiobuccal cusp point. Mandibular anthropometric points: 27, Coronoid point; 28, Coronoid notch point; 29, Condylion point; 30, Gonion point; 31, Gnathion; 32, Mn point; 33, Antegonial incisure; 34, Anterior masseteric line; 35, Menthon point; 36, Mandibular alveolar point; 37, Infradental point; 38, Incisive inferior alveolar point; 39, L1, incisal point; 40, L1, cervicolabial point; 41, L1, cervicolingual point; 42, L1, mesial point; 43, L1, distal point; 44, L6, mesial point; 45, L6, mesiobuccal cusp point; 46, L8, distal point; 47, L8, mesiobuccal cusp point. (b) Anthropometric measurements. Cranial Measurements: 1, Total skull length; 2, Nasal length; 3, Nasal width; 4, Interorbital width; 5, Interzygomatic width; 6, Maximum skull width; 7, Maximum skull height; 8, Upper anterior facial height; 9, Lower anterior facial height; 10, Total anterior facial height. Maxillary measurements: 11, Total maxillary length; 12, Incisive foramen width; 13, Maxillary width; 14, U6 intermolar width; 15, U8 intermolar width; 16, U1 incisor crown height; 17, U6 height; 18, Maxillary posterior arch length; 19, U1, labiolingual distance; 20, U1, mesiodistal distance. Mandibular measurements: 21, Mandibular length I; 22, Mandibular length II; 23, Mandibular length III; 24, Corpus length; 25, Ramus height I; 26, Ramus height II; 27, Ramus height III; 28, Ramus height IV; 29, Corpus height; 30, Mandibular plane angle; 31, Bicoronoidal width; 32, Bicondylar width; 33, Bigonial width; 34, L6 intermolar width; 35, L8 intermolar width; 36, L1, incisor crown height; 37, L6 height; 38, Mandibular posterior arch length; 39, L1, labiolingual distance; 40, L1, mesiodistal distance.

Changes in weight over time. Weight gain remained stable throughout the study. Neither disturbances in growth nor clinically evident differences in animal size or shape were seen. No statistically significant differences were found in animal weights.

Changes in muscle mass. Masseter muscles were smaller in BoNT/A-treated groups (I and III). Temporalis muscles were smaller in BoNT/A-treated groups (II and III). **p<0.001.