Periodontal Ligament Reactions to Orthodontic Force: A Transcriptomic Study on Maxillary and Mandibular Human Premolars.

AIMS: Orthodontic force (OF) induces a variety of reactions in the periodontal ligament (PDL) that could potentially account for individual variability regarding orthodontic tooth movement (OTM). This study investigates the transcriptomic profile of human PDL tissue subjected to OF in vivo for 7 and 28 days, additionally comparing the differences between maxillary and mandibular PDL. METHODS: Healthy patients requiring orthodontic premolar extractions were randomly assigned to one of three groups: control (CG) where no OF was applied, 7 days and 28 days, where premolars were extracted either 7 or 28 days after the application of a 50-100 g OF. Total RNA was extracted from the PDL tissue and analyzed via RNA-seq. Differentially expressed genes (DEGs) were identified using a false discovery rate and fold change threshold of < 0.05 and ≥ 1.5 respectively. Functional and Protein-Protein Interaction analysis were performed. RESULTS: After 7 days of OF, the reaction of PDL to OF is characterized by cell responses to stress, increased bone resorption, inflammation and immune response, and decreased bone formation. In contrast, after 28 days, bone regeneration is more prominent, and processes of bone homeostasis, immune response, and cell migration are present. The response of maxillary and mandibular PDL was different. Bone resorption was observed in the maxilla at 7 and 28 days, while in the mandible expression of cell proliferation and transcriptional activity were predominant after 28 days of OF. CONCLUSIONS: The early reaction of the PDL to OF corresponds with increased bone resorption and decreased bone formation. After 28 days, bone formation became more prominent. The maxillary and mandibular PDL present asynchronous responses during OTM. These findings enhance our comprehension of the mechanisms underlying the origin-specific responses of PDL to different lengths of OF, which is potentially relevant in the development of personalized therapeutic strategies.

Correlation between oral muscle pressure and malocclusion in mixed dentition: a cross-sectional study.

OBJECTIVE: To investigate the relationship between oral muscle pressure and malocclusion in the mixed dentition. MATERIALS AND METHODS: Maximum tongue, lip and cheek pressure was measured using the Iowa Oral Performance Instrument (IOPI) in 3 patient cohorts: patients with (1) posterior crossbite, (2) class II relationship and (3) a control group of patients without malocclusion. Linear models were used to compare the mean differences in muscle pressure between groups, with correction for age and gender. The imbalance between lips and tongue and between lips and cheeks was calculated by the Delta z-scores of each group. RESULTS: A total of 146 participants were included, 46 (mean age 8.71±0.85), 41 (mean age 11.74±1.17) and 35 (mean age 10.71±1.92) in groups 1, 2 and 3 respectively. Patients with malocclusion showed significantly higher lip and lower cheek pressure and imbalance favouring the lips over the tongue compared to controls. Class II,1 patients showed significantly higher tongue pressure than Class II,2. No differences were found in muscle pressure or imbalance between crossbite and Class II nor between crossbite types. CONCLUSION AND CLINICAL RELEVANCE: These findings suggest that oral muscle pressure may be associated with malocclusion. This highlights the importance of functional diagnosis and its implications on the prevention and treatment of malocclusion, as well as on orthodontic stability.

Influence of age and diet consistency on the oral muscle pressure of orthodontically treated and untreated subjects with normal occlusion and comparison of their 3D facial shape.

OBJECTIVES: (1) To investigate the effect of age and diet consistency on maximum lips, tongue and cheek pressure of orthodontically treated and untreated subjects with normal, Class I dental occlusion, (2) to find out whether there is a muscle imbalance between anterior tongue and lip pressure in the same subjects at different ages and (3) to compare the 3D facial shape of treated and untreated individuals. MATERIAL AND METHODS: Subjects with normal occlusion were prospectively grouped into orthodontically treated/untreated and in children/adolescents/adults. Iowa Oral Performance Instrument was used to record the maximum muscle pressure. Two-way ANOVA and Tukey post hoc test analysed age-specific differences in muscle pressure. Two-way ANCOVA analysed the effect of diet consistency on muscle pressure. Lips and tongue imbalance was analysed using z-scores and 3D faces using a generalized Procrustes analysis. RESULTS: One hundred thirty-five orthodontically untreated and 114 treated participants were included. Muscle pressure was found to increase with age in both groups, except for the tongue in treated subjects. No differences in the balance between lips and tongue muscle pressure were found, but a higher cheek pressure in untreated adults (p<0.05) was observed. 3D facial shapes showed subtle differences. Untreated subjects with soft diet consistency showed lower lip pressure (p<0.05). CONCLUSION: Oral muscle pressure of orthodontically treated patients without relapse does not differ from that of untreated patients with Class-I occlusion. CLINICAL RELEVANCE: This study provides normative lip, tongue and cheek muscle pressure in subjects with normal occlusion, which can be used for diagnosis, treatment planning and stability.

Skeletal and soft-tissue changes in humans with untreated normal occlusion throughout lifetime: a systematic review.

Age-related skeletal and soft-tissue changes are important in orthodontics, especially due to the increase of adult patients seeking treatment. The aim of this study is to assess the available evidence regarding age-related skeletal and soft-tissue changes in untreated Angle Class I. Articles studying skeletal and soft-tissue changes in orthodontically untreated subjects with Angle Class I and comparing them between age groups were included. Studies focusing on a single age group or in languages other than English were excluded. Risk of bias was assessed with both the MINORS and ROBINS-I tools. 50 studies were included, showing high methodological heterogeneity and a lack of information in subjects over 60 years old. In subjects with Angle Class I, the mandibular plane inclination was reported to reduce from 7 and 20 years old, while the anterior and posterior facial height continue to increase in late adult life. The anterior cranial base length increases until 20 years old, afterwards decreasing slowly until late adulthood. Nasal width increases and the nasolabial angle decreases during adolescence. Upper lip length and lower lip length increase from 6 to 18 years along with retrusion of the lips in late adulthood. Age-related skeletal and soft-tissue changes are documented in the literature from childhood until the fifth decade of life, but studies mostly focus on subjects until 20 years old. Changes after the second decade of life are studied only for the vertical and sagittal dimensions. No changes are reported in the transversal dimension beyond 15 years for neither skeletal nor soft tissues. Well-designed, long-term prospective cohort studies considering all three dimensions of skeletal and soft tissues are needed for confirmation of these findings (PROSPERO: CRD42020203206).

Long-term three-dimensional effects of orthognathic surgery on the pharyngeal airways: a prospective study in 128 healthy patients.

OBJECTIVE: To investigate volumetric and circumferential pharyngeal airway space (PAS) changes and stability over time as evaluated with cone beam computed tomography (CBCT) before and after orthognathic surgery 2 years postoperatively. MATERIALS AND METHODS: One hundred twenty-eight patients underwent bimaxillary orthognathic surgery at the Department of Maxillofacial Surgery of University Hospitals, Leuven, Belgium, were recruited prospectively. Patients were divided into 4 groups based on the amount of mandibular advancement in 5 mm increments (< 0 mm, 0-5 mm, 5-10 mm, or > 10 mm). CBCT data was acquired preoperatively and 1-6 weeks, 6 months, 1 year, and 2 years postoperatively. Patients with a history of maxillofacial trauma or surgery, obstructive sleep apnoea syndrome, or craniofacial anomalies were excluded. Nasopharyngeal, oropharyngeal, and hypopharyngeal PAS volumes and constriction surface areas (mCSA) were measured and compared between each time point with a paired t-test. RESULTS: The largest significant increase in oropharyngeal volume and mCSA were observed in the 5-10 mm (+ 13.3-21.7%, + 51.3-83.0%)) and > 10 mm (+ 23.3-44.6%, + 92.3-130.0%) mandibular advancement groups. This increase only remained stable 2 years postoperatively in the > 10 mm group. In other mandibular advancement groups, short-term oropharyngeal volume and mCSA increases were noticed, which returned to baseline levels 6 months to 1 year postoperatively. CONCLUSION: Bimaxillary advancement osteotomy significantly increases oropharyngeal volume and mCSA, which remains stable between 6 months to 1 year postoperatively. CLINICAL RELEVANCE: Long-term stable volumetric and mCSA enlargements were found with > 10 mm mandibular advancements over a period of 2 years. Return towards baseline levels was observed in the other mandibular advancement groups.

Assessment of craniofacial maturation in preadolescents with cleft lip and/or palate using the cervical vertebral maturation method.

OBJECTIVES: Aberrant growth of the maxillomandibular complex in patients with cleft lip and/or palate (CL/P) can be managed with dentofacial orthopaedics. However, no consensus has been reached regarding timing and evolution of the maturational stages. Therefore, the aim of this study is to determine if patients with CL/P have an increased risk for delayed craniofacial maturation. MATERIALS AND METHODS: A sample of 246 cleft patients and 210 non-affected individuals was retrospectively compiled. Cephalometric radiographs taken between the ages of 10 and 14 years (girls) and 12 and 16 years (boys) were collected and assessed with the cervical vertebral maturation (CVM) method. RESULTS: In boys, no significant association between the presence of CL/P and a CVM score of CS3 or higher was observed in any age subsample. This was similar for a CVM score of CS5 or higher. Girls in the CL/P group had a significant lower probability of having a CVM score of at least CS3 in the subsample with age 11 to 12 (p = 0.001) and a borderline non-significant lower probability of having a CVM score of at least CS5 in the subsample with age 12 to 13 (p = 0.055). CONCLUSIONS: The current study demonstrated a discrete delay in skeletal maturation before the pubertal growth spurt of (pre)adolescents with CL/P, especially girls. This delay was less apparent at the end of the pubertal growth spurt. CLINICAL RELEVANCE: This research suggests that the craniofacial maturational stages relevant for dentofacial orthopaedic treatment in cleft patients, especially girls, occur at higher chronological age. Further research must quantify this delay, investigate its clinical significance, and determine its effect on the timing of dentofacial orthopaedic treatment.

Dental and Craniofacial Characteristics in Patients With 14Q22.1-Q22.2 Deletion: A Case Series.

This case series is a follow-up report focusing on dental and facial characteristics in patients with a rare microdeletion in chromosome 14q22.1-q22.2. Usually, these patients have severe ocular, brain, and digital abnormalities. However, this case series shows that clinical presentation can be mild. Four relatives spanning 3 generations were diagnosed with a familial autosomal dominant 2.79 Mb microdeletion in chromosome 14q22.1-q22.2. Genetic screening was done by the Bacterial Artificial Chromosome array-comparative genome hybridization and was confirmed by the fluorescence in situ hybridization technique. Dental and craniofacial data were collected from medical files, clinical examinations, clinical photos, panoramic and cephalometric radiographs, and dental casts. Written informed consent for scientific use was obtained for all family members. No larger syndrome could be identified. All cases had similar facial red flag characteristics, consisting of a long face with retrognathia and open mouth relation, associated oral clefts in varying degrees, depressed nasal bridge, delayed tooth development, hypertelorism, and low-set angular ears. The dental casts showed a distal molar occlusion and a lack of space in the dental arches. Developmental delay was noted together with limb defects such as poly- and syndactyly. Microphthalmia and hearing loss were present in the most severe cases. This rare congenital disorder, associated with facial dysmorphia, oral clefts, and tooth agenesis, can remain undiagnosed until adulthood. A family history of short stature, developmental delay, poly- or syndactyly, and micropthalmia are suggestive features. Similar reports help to raise awareness among dental practitioners, leading to an early genetic diagnosis.

Validation of a novel method for canine eruption assessment in unilateral cleft lip and palate patients.

OBJECTIVE: The aim of this study was to propose and validate a three-dimensional (3D) methodology for the assessment of canine eruption in patients born with unilateral cleft lip and palate (UCLP) following secondary alveolar bone graft (SABG). METHODS AND MATERIALS: A total of 10 patients (four females, six males; mean age: 8.8 years) with UCLP who underwent SABG were recruited. Pre- and 6-month post-operative cone-beam computed tomography (CBCT) was acquired for all patients. Post-operative data was registered onto pre-operative data utilizing voxel-based registration. Following superimposition, a segmentation process was applied to segment maxillary canine on both cleft and non-cleft side. Thereafter, translational and rotational changes in canine position were assessed for both cleft and non-cleft side by two observers. RESULTS: The intra-class correlation coefficient (ICC) indicated excellent reliability (≥0.90) with inter and intra-observer error of less than 0.05 mm. The overall ICC was found to be high for assessing both translational and rotational changes. The mean absolute inter- and intra-observer difference for translational and rotational changes was found to be less than 1 mm and 3°. CONCLUSION: The present method was found to be reliable proving to be clinically applicable for assessing maxillary canine eruption changes in both cleft and non-cleft bone.