Myosin Heavy-Chain Messenger Ribonucleic Acid (mRNA) Expression and Fibre Cross-Sectional Area in Masseter, Digastric, Gastrocnemius and Soleus Muscles of Young and Adult Rats.

Different demands on the muscles of mastication may influence their functional profile (size and distribution of muscle fibre types), which may change during growth and maturation, potentially influencing craniofacial growth. The aim of this study was to evaluate mRNA expression and cross-sectional area of masticatory muscle fibres compared with limb muscles in young and adult rats. Twenty-four rats were sacrificed at two different ages, namely 12 at 4 weeks (young) and 12 at 26 weeks (adult).

Longitudinal changes of the insertion of the maxillary labial frenum in children and adolescents undergoing orthodontic treatment.

Introduction: This study aimed to evaluate potential vertical changes in the position of the maxillary labial frenum (MLF) insertion in growing children and to compare these changes to the vertical growth of the dentoalveolar process and lower facial third.

Methods: This retrospective longitudinal study investigated records of 33 healthy children. Dental casts, lateral cephalograms, and photographs were evaluated at pretreatment (T0), posttreatment (T1), and 3-5 years into retention (T2).

Mandibular antegonial notch depth in postpubertal individuals: A longitudinal cohort study.

Objectives: To perform an epidemiological analysis of the antegonial notch depth in postpubertal individuals and to analyze the development of deep antegonial notches longitudinally in growing individuals. MATERIAL AND METHODS: Lateral cephalograms of 302 untreated 17/18-year-old subjects (171 males; 131 females), from the craniofacial growth legacy collection, were analysed to measure antegonial notch depth along the mandibular plane. Sex and sagittal malocclusion were investigated as possible factors influencing notch depth.

Mandibular condyle changes in rats with unilateral masticatory function.

Objective: Certain malocclusions or unilateral tooth loss can lead to asymmetric functional load of the two mandibular sides during mastication and induce skeletal asymmetries to the condylar process of growing individuals. However, in adults, asymmetric function may have a different impact. The aim of the present study was to investigate three-dimensionally the effects of unilateral masticatory function on the condylar process morphology in growing and adult rats and the adaptive processes to differential condylar loading.

Monitoring Overeruption Pattern of Young vs Adult Unopposed Molars in the Rat.

Purpose: To investigate the overeruption of unopposed molars and the adaptation of alveolar bone height in young and adult rats.

Materials And Methods: A total of 56 4-week-old (young) and 26-week-old (adult) male Wistar rats were followed up longitudinally. In each age group (n = 28), 16 rats were included in the experimental subgroup, in which all the maxillary right molars were extracted, and 12 rats were included in the control subgroup.

Core Matrisome Protein Signature During Periodontal Ligament Maturation From Pre-occlusal Eruption to Occlusal Function.

The pre-occlusal eruption brings the molars into functional occlusion and initiates tensional strains during mastication. We hypothesized that upon establishment of occlusal contact, the periodontal ligament (PDL) undergoes cell and extracellular matrix maturation to adapt to this mechanical function. The PDL of 12 Wistar male rats were laser microdissected to observe the proteomic changes between stages of pre-occlusal eruption, initial occlusal contact and 1-week after occlusion.

A longitudinal study on timing and velocity of rat molar eruption: Timing of rat molar eruption.

Rat molar eruption and occlusion data were compiled from several studies but several inconsistencies were found, rendering the planning of eruptional studies difficult and imprecise. Our aim was to measure eruption and occlusion days, as well as eruption velocity, in the upper and lower three molars from infancy to end of adolescence in the rat. A total of 19 male and female Wistar rats were scanned daily by micro-computed tomography (CT) from day 15 to 70.

Effect of different masticatory functional demands on the 3D mandibular condyle morphology of growing rats using posterior bite-blocks.

Background And Objectives: Apart from the primary effect of bite-blocks on tooth position, they may also influence the mandibular condylar growth. Our aim was to investigate their influence on the condylar morphology, with variable masticatory forces.

Material And Methods: Fifty-two 4-week old male rats were divided into hard and soft diet groups in order to create individuals with different masticatory muscle capacity.

The influence of altered functional loading and posterior bite-blocks on the periodontal ligament space and alveolar bone thickness in rats.

Objectives: Posterior bite-blocks are resin-based structures elevating the occlusion and creating intrusive force on the posterior teeth. Bite-blocks were applied to the molars of growing rats and a hard and soft diet was used to create altered functional masticatory forces. The aim of the present investigation was to study the effect of this appliance on the periodontal ligament space and alveolar bone thickness when combined with altered masticatory forces.

Influence of masticatory hypofunction on the alveolar bone and the molar periodontal ligament space in the rat maxilla.

Previous studies have established that complete absence of masticatory function results in a narrower alveolar process and periodontal ligament (PDL). The aim of our study was to investigate, for the first time, both the alveolar process and the PDL in masticatory hypofunction. Twenty-six rats, 3 wk of age, were randomly assigned to either a hard- or a soft-diet group (n = 13 each group).