Mouse cellular cementum is highly dependent on growth hormone status

Clinical Implications of Growth Hormone Deficiency for Oral Health in Children: A Systematic Review

Growth hormone (GH) is involved in the regulation of the postnatal dental and skeletal growth, but its effects on oral health have not been clearly defined. This paper aims to provide a review of current clinical knowledge of dental caries, tooth wear, developmental enamel defects, craniofacial growth and morphology, dental maturation, and tooth eruption in growth hormone deficient (GHD) children. A systematic review was carried out using Scopus, MEDLINE-EbscoHost and Web of Science from 2000 to May 2021. PRISMA guidelines for reporting systematic reviews were followed. All the selected studies involved groups under eighteen years of age, covering a total of 465 GHD patients. The studies that were selected provide reliable evidence for delayed dental maturity and orthodontic disturbances in GHD patients. Data on dental hard tissues pathology are scarce and are limited to occurrences of dental caries. GHD children showed abnormal craniofacial morphology with reduced mandibular dimensions, with a resulting tendency towards Angle's Class II occlusion, which affected up to 31% of patients. Dental age has been shown to be delayed in GHD patients by about 1 to 2 years. Moreover, the risk of dental caries in children with GHD decreases with increasing levels of vitamin D. Hence, further studies would be valuable for evaluating the risk of various oral health problems and to organize targeted dental care for this vulnerable group.

The Role of GH/IGF Axis in Dento-Alveolar Complex from Development to Aging and Therapeutics: A Narrative Review

The GH/IGF axis is a major regulator of bone formation and resorption and is essential to the achievement of normal skeleton growth and homeostasis. Beyond its key role in bone physiology, the GH/IGF axis has also major pleiotropic endocrine and autocrine/paracrine effects on mineralized tissues throughout life. This article aims to review the literature on GH, IGFs, IGF binding proteins, and their respective receptors in dental tissues, both epithelium (enamel) and mesenchyme (dentin, pulp, and tooth-supporting periodontium). The present review re-examines and refines the expression of the elements of the GH/IGF axis in oral tissues and their in vivo and in vitro mechanisms of action in different mineralizing cell types of the dento-alveolar complex including ameloblasts, odontoblasts, pulp cells, cementoblasts, periodontal ligament cells, and jaw osteoblasts focusing on cell-specific activities. Together, these data emphasize the determinant role of the GH/IGF axis in physiological and pathological development, morphometry, and aging of the teeth, the periodontium, and oral bones in humans, rodents, and other vertebrates. These advancements in oral biology have elicited an enormous interest among investigators to translate the fundamental discoveries on the GH/IGF axis into innovative strategies for targeted oral tissue therapies with local treatments, associated or not with materials, for orthodontics and the repair and regeneration of the dento-alveolar complex and oral bones.

Assessment of oro-dental manifestations in a series of acromegalic patients, the AcroDent study

OBJECTIVE

The dental and periodontal impact of GH/IGF-1 hypersecretion has been poorly investigated until now. Our aim is to precisely describe the oro-dental state of acromegalic patients and to study the impact of GH/IGF-1 hypersecretion on patients' reported oral health-related quality of life (OHRQoL).

METHODS

After collecting characteristics of their disease, acromegalic patients answered the GOHAI questionnaire assessing their OHRQoL, the AcroQoL questionnaire and then benefited from a complete stomatological and radiological examination (orthopantomogram systematically, retro-alveolar radiography or Cone Beam CT if necessary).

RESULTS

In total, 29 patients aged 59.1 ± 16.0 years were included. The average DMFT index (sum of Decayed, Missing and Filled Teeth per patient) was 19.0 ± 7.8. 16/29 patients had a gingivitis and 18/29 a mild to moderate chronic periodontitis, but no case of severe chronic periodontitis was found, probably because the frequency of a protective thick gingival biotype was increased (9/29). No case of generalized gingival hypertrophy or diffuse hypercementosis was observed. According to the Add-GOHAI score, only 8/26 patients had a satisfactory OHRQoL. This parameter was correlated to the acromegaly-specific quality of life according to the AcroQoL score. Interestingly, 11/29 patients had bulky oral bony outgrowths (OBO), such as large maxillary or mandibular tori and multiple vestibular exostosis.

CONCLUSIONS

The unsatisfactory OHRQoL reported by acromegalic patients contrasts with a rather good objective oro-dental state and annual oral examination seems relevant in this population. Finally, we report that huge OBO could be helpful signposts for the diagnosis of acromegaly.

ACVR1 is essential for periodontium development and promotes alveolar bone formation

OBJECTIVE

To explore the role of a BMP type I receptor (ACVR1) in regulating periodontium development, Acvr1 was conditionally disrupted in Osterix-expressing cells.

METHODS

Mandibles from both control (Acvr1 fx/+; Osterix-Cre (+)/(-)) and cKO (Acvr1 fx/-; Osterix-Cre (+)/(-)) mice at postnatal day 21 (PN21) were scanned by micro-CT, followed by decalcification and histological observations. Distributions and levels of differentiation markers of fibroblasts, osteoblasts and cementocytes in the periodontium were detected by immunohistochemical (IHC) staining.

RESULTS

Micro-CT results showed that bone mass and bone mineral density of the alveolar bones in the cKO mice were lower than those in the controls. Histomorphometry within the alveolar bones revealed that the lower bone mass observed in the cKO mice was caused by increased numbers and resorption activities of osteoclasts. The markers for osteoblast differentiation, Col I and DMP1, were reduced and the signals of the RANKL/OPG ratio were increased in the alveolar bones of the cKO mice compared to those of the control mice. The periodontal ligament in the cKO mice exhibited disorganized collagen fibers with weaker signals of Col I and periostin. However, there was no difference in terms of the cellular cementum between the two groups.

CONCLUSION

ACVR1 is essential for normal periodontium development. ACVR1 in the osteoblasts negatively regulates osteoclast differentiation in association with the RANKL/OPG axis and thus promotes alveolar bone formation.

Growth hormone receptor gene is related to root length and tooth length in human teeth

OBJECTIVES

To examine the relationship between tooth length and growth hormone receptor (GHR) gene variants in a healthy Japanese population.

MATERIALS AND METHODS

The subjects consisted of 193 Japanese adults (69 men, 124 women), aged 13 to 56 years. Genomic DNA was extracted from saliva and genotyped GHR rs6184 and rs6180 variants using the Taqman genotyping. Computed tomography (CT) images were acquired using a dental cone-beam CT scanner and reconstructed using open-source OsiriX medical image processing software. The maxillary (upper; U) and mandibular (lower, L) central incisors (1), lateral incisors (2), canines (3), first premolars (4), second premolars (5), first molars (6), and second premolars (7) were evaluated. Teeth were assessed for crown height (CH), root length (RL), overall tooth length (C+R), and crown to root ratio (C/R). The relationships between GHR variants and CH, RL, C+R, and C/R were statistically examined.

RESULTS

The GHR variant rs6184 was associated with the root lengths and tooth length for the upper and lower lateral incisors and upper canines (U2 RL; U3 RL, C+R; L2 RL [ P < .05]).

CONCLUSIONS

The results indicate that the GHR rs6184 variant is associated with tooth length and ratio dimensions in a Japanese cohort. Further studies utilizing a larger sample size are needed to confirm this finding.

Growth Hormone and Craniofacial Tissues. An update

Growth hormone is an important regulator of bone homeostasis. In childhood, it determines the longitudinal bone growth, skeletal maturation, and acquisition of bone mass. In adulthood, it is necessary to maintain bone mass throughout life. Although an association between craniofacial and somatic development has been clearly established, craniofacial growth involves complex interactions of genes, hormones and environment. Moreover, as an anabolic hormone seems to have an important role in the regulation of bone remodeling, muscle enhancement and tooth development. In this paper the influence of growth hormone on oral tissues is reviewed.

Ex vivo evaluation of caries infiltration after different application times in primary molars

Low viscosity resins (infiltrants) have been shown to penetrate the lesion body of natural caries lesions almost completely in vitro. However, penetration depths (PD) have not been evaluated in vivo. Therefore, the aim of the present study was to evaluate the penetration of an infiltrant into proximal caries lesions in primary molars after different application times using an ex vivo model. 59 proximal lesions from 34 children were randomly allocated to one of the application times and were infiltrated under clinical conditions for 1, 3, or 5 min. After extraction or exfoliation (n = 48), teeth were sectioned perpendicular to their surfaces and lesion depths (LD) as well as lesion areas (LA) were evaluated using polarized light microscopy. PD and penetration areas (PA) were measured on scanning electron microscopic images. Percentage penetration depth (PPD) and percentage penetration area (PPA) were calculated. The mean (±SD) LD and LA were 596 ± 203 µm and 4.03 ± 2.75 × 10(5) µm(2), respectively. PPD ranged from 70 to 80% and PPA from 54 to 60%. Longer application times did not result in significantly deeper or more complete penetration (p > 0.05; ANOVA). In conclusion, proximal caries lesions in primary molars can be infiltrated in vivo to a similar extent as observed previously in vitro. Moreover, 1-min application of the infiltrant led to PD and homogeneity similar to those observed with longer application times up to 5 min.

Endocrine parameters and phenotypes of the growth hormone receptor gene disrupted (GHR-/-) mouse

Disruption of the GH receptor (GHR) gene eliminates GH-induced intracellular signaling and, thus, its biological actions. Therefore, the GHR gene disrupted mouse (GHR-/-) has been and is a valuable tool for helping to define various parameters of GH physiology. Since its creation in 1995, this mouse strain has been used by our laboratory and others for numerous studies ranging from growth to aging. Some of the most notable discoveries are their extreme insulin sensitivity in the presence of obesity. Also, the animals have an extended lifespan, which has generated a large number of investigations into the roles of GH and IGF-I in the aging process. This review summarizes the many results derived from the GHR-/- mice. We have attempted to present the findings in the context of current knowledge regarding GH action and, where applicable, to discuss how these mice compare to GH insensitivity syndrome in humans.

Extrapituitary growth hormone

Pituitary somatotrophs secrete growth hormone (GH) into the bloodstream, to act as a hormone at receptor sites in most, if not all, tissues. These endocrine actions of circulating GH are abolished after pituitary ablation or hypophysectomy, indicating its pituitary source. GH gene expression is, however, not confined to the pituitary gland, as it occurs in neural, immune, reproductive, alimentary, and respiratory tissues and in the integumentary, muscular, skeletal, and cardiovascular systems, in which GH may act locally rather than as an endocrine. These actions are likely to be involved in the proliferation and differentiation of cells and tissues prior to the ontogeny of the pituitary gland. They are also likely to complement the endocrine actions of GH and are likely to maintain them after pituitary senescence and the somatopause. Autocrine or paracrine actions of GH are, however, sometimes mediated through different signaling mechanisms to those mediating its endocrine actions and these may promote oncogenesis. Extrapituitary GH may thus be of physiological and pathophysiological significance.

Comparison of visual inspection and different radiographic methods for dentin caries detection on occlusal surfaces

OBJECTIVES

The aim of the present study was to assess the validity of the digital phosphor plate radiographic technique (Gendex Dental Systems) on occlusal surfaces in comparison with visual examination and conventional E- and F-speed films.

METHODS

The study material consisted of 54 non-cavitated third molars with a range of appearances, including apparently sound surfaces. Each surface was visually examined (VI) according to the criteria established by Ekstrand et al. Three radiographic images (E-speed, F-speed, digital phosphor plate film) were taken of each molar. The standardized radiograph technique used an alignment fixture to reproduce the focus-to-object distance as well as the object-to-film distance. Afterwards each tooth was cut into sections in the buccolingual direction with a microtome saw, and caries extension was assessed using light microscopy (LM) and microradiography (MR). The statistical analysis included the calculation of sensitivity (SE), specificity (SP) and A(z) values.

RESULTS

The following validity parameters were found for the tested diagnostic methods on the dentin caries level: VI/LM, 68.0 SE/93.1 SP/0.698 A(z); VI/MR, 68.2/87.5/0.751; E-speed/LM, 76.0/78.6/0.637; E-speed/MR, 77.3/74.2/0.681; F-speed/LM, 64.0/67.9/0.507; F-speed/MR, 68.2/67.7/0.594; Gendex/LM, 60.0/85.7/0.629; and Gendex/MR, 59.1/80.6/0.586.

CONCLUSION

The methods used showed different levels of validity: E- and F-speed films were linked to higher sensitivity values, whereas a higher specificity was recorded for the tested imaging plate system. In accordance with the diagnostic performance, the digital system can be recommended for practical use and potentially help prevent overtreatment thanks to its high SP.

Activation of the growth hormone receptor

Growth hormone (GH) is a major regulator of postnatal growth and metabolism. There are extensive clinical applications for GH or its antagonists, including treatments for dwarfism, cancer and metabolic wasting. Owing to this, there is considerable interest in the mechanisms of GH receptor (GHR) activation. It is conventionally thought that GH induces dimerization of two GHR monomers, which initiates intracellular signaling cascades. However, recent studies have provided evidence for a ligand-induced conformational change within constitutively dimerized GHRs being responsible for activating signaling pathways. This review will relate the new model of GHR activation to the activation of related cytokine receptors and discuss the implication of this new model for the design of small GH mimetics and antagonists for therapeutic use.

Influence of growth hormone on the craniofacial complex of transgenic mice

Growth hormone (GH) secretion affects bone and cartilage physiology. This study investigated the effect of GH on the size of the craniofacial structures and their angular relationship. Three different models of mice with a genetically altered GH axis were used: GH excess (giant), dwarf GH antagonist (dwarf-Ant), and dwarf GH receptor knockout (dwarf-KO) mice. Each model was compared with the corresponding wild type (Wt). Five craniofacial distances were analysed: craniofacial length, upper face height, mandibular anterior height, mandibular ramus length, and mandibular corpus length. In addition, upper and lower incisor lengths and four angular relationships, nasal bone with cranial base, maxillary plane with cranial base, mandibular plane with cranial base, and the angle of the mandible, were determined. Data were analysed by one-way ANOVA. Craniofacial length, upper face height and mandibular corpus length were significantly increased in the giant mice and significantly reduced in the dwarf mice. Mandibular anterior height and mandibular ramus length were significantly affected in the dwarf-KO mice but not in the giant mice. The length of both the upper and lower incisors was significantly increased and reduced in the giant and dwarf-KO mice, respectively. In addition, the angle of the mandible was significantly increased in the giant mice and significantly reduced in the dwarf mice. It is concluded that GH plays a major role in the growth and development of the craniofacial complex by directly and indirectly modulating the size and the angular relationships of the craniofacial structures, including the incisor teeth.