General characteristics

Disturbances in GH production can lead to GH deficiency (GHD), which can be either isolated (IGHD) or combined with other general medical conditions. Etiological factors for GHD may include pituitary gland abnormal function, syndromes such as Turner syndrome, and others. The clinical characteristics vary according to the etiological factor, the age of the child at onset of the disorder, and the severity of the deficiency. GHD has been found to cause impairment of growth of the long bones of the body, and abnormal development of the maxilla, the mandible, and the dentition in children.

Craniofacial and oral manifestations

GHD has a negative effect on the total length of the maxilla (Oliveira‐Neto et al., 2011), causing midfacial hypoplasia, while severe deviations are found also in the total length and the mandibular body (Salas‐Flores et al., 2010), resulting in Angle’s Class II malocclusion (Torlińska‐Walkowiak et al., 2021). The retrognathism of the mandible and maxilla is best evidenced by the values of the SNA° and SNB° angles (Preda et al., 2019). In the vertical plane, the posterior facial height (PFH) is smaller (Pirinen et al., 1994), while there is an open bite tendency with mandibular retrusion and convex profile (Salas‐Flores et al., 2010). Regarding the anterior cranial base, its length was found to be decreased (Salas‐Flores et al., 2010; Preda et al., 2019) and the cranial base angle (CL‐SPhen) was smaller than in controls (Pirinen et al., 1994). In an attempt to create a classification of the affected structures, the total maxillary length was found to be the most reduced linear parameter followed by the posterior cranial base length, total mandibular length, total PFH, total anterior facial height (AFH), mandibular body length, and anterior cranial base length (Oliviera‐Neto et al., 2011; Davidopoulou and Chatzigianni, 2017).

A relatively common clinical finding in children with GHD is a mean delay in dental age by about 1–2 years (Torlińska‐Walkowiak et al., 2021). Studies in humans have also demonstrated that genetic polymorphisms in estrogen receptors and in GH receptors are associated with alterations in ameloblast function and developmental defects of enamel (Arid et al., 2019). The presence of a single central incisor in children with GHD may be predictive of median line and pituitary gland disorders (Hamilton et al., 1998; Figure 5.1).

Orthodontic considerations

There is evidence that GH replacement therapy has a beneficial effect on the craniofacial complex (Partyka et al., 2018); facial convexity improves, mandibular length and lower facial height increase, while the arch width remains constant (Poole et al., 1982). Catch‐up growth in height, skeletal age, AFH, PFH, and posterior cranial base length are evident with hormonal therapy (Cantu et al., 1997).

The effect of GH on dental development remains controversial. According to some studies, when GH replacement treatment is started early and lasts longer, the dental age is accelerated (Partyka et al., 2018). Nevertheless, in other studies GH did not markedly affect dental maturation (van Erum et al., 1998). The orthodontist should evaluate all possible deviations from the norm and the effect of GH replacement therapy on the craniofacial bones and the dentition before orthodontic treatment commences.

General characteristics

Gigantism occurs when an increase in GH production commences before the fusion of the long bone epiphysis and is characterized by tall body height. Acromegaly occurs after adolescence, when GH hypersecretion occurs following the completion of skeletal maturity, leading to large extremities and characteristic facies. Elevated IGF‐1 levels confirm the diagnosis (Bello and Garla, 2021).

Craniofacial and oral manifestations

The characteristic extraoral features include a prominent forehead and growth of the nose and ears (Kamal et al., 2020). In male acromegaly patients the nasal width, length, height, and depth were found to be increased and IGF‐1 levels were linearly and positively correlated with nose width (Guo et al., 2018; Figure 5.2). Facial widths and facial heights were found to be much larger, along with an elongated clivus (Pirinen et al., 1994). Head dimensions and the cranial base angle were within normal values in patients with GH excess. A protrusion of the mandible is generally frequently observed and the gonion–gnathion distance is longer (Guo et al., 2018). When examined periorally, common findings in these patients are thicker upper lips and macroglossia with profound interdental spacing. Taurodontism can be seen on dental radiographs (Akintoye et al., 2003; Guo et al., 2018).

Orthodontic considerations

Patients with gigantism or acromegaly require detailed examination and thorough coordination between endocrinologists, orthodontists, and oral surgeons before the commencement of any treatment.

General characteristics

Hypothyroidism refers to decreased production of THs from the thyroid gland, which leads to lower levels of those hormones in the blood. The mean prevalence of hypothyroidism in Europe was found to be 3.05% of the population (Garmendia Madariaga et al., 2014). The etiological factors may vary and be diverse, but clinical manifestations seem to be quite homogeneous. The most frequent disorder of autoimmune origin with clinical hypothyroidism is Hashimoto thyroiditis (HT). HT has the highest prevalence in the general population among hypothyroidism disorders and is characterized by reduced levels of thyroxine (fT4) and the metabolically active free triiodothyronine (fT3).

Frequently, myopathies are a severe symptom of hypothyroidism (Fariduddin and Bansal, 2021). Untreated hypothyroidism may cause general inflammation of the body’s joints (Grozdinska et al., 2018).

Craniofacial and oral manifestations

Severe HT may cause subnormal growth of the maxilla and mandible and a decrease in facial dimensions. In an animal study on rats, the palatal, cranial, bizygomatic arch, and bigonial width measurements were significantly shorter in the HT groups compared to the control group. Cephalometric radiographs indicated that statistically significant differences were present in the HT groups for almost all linear and angular measurements (Gecgelen Cesur et al., 2016). A significantly elevated prevalence of temporomandibular disorder was found in patients with HT (Grozdinska et al., 2018; Figure 5.3).

Timing of tooth eruption, mineralization of tooth enamel, maxillary and mandibular bone, tongue morphology, and periodontal status are affected according to several studies (Chandna and Bathla, 2011; Dudhia and Dudhia, 2014, Vucic et al., 2017). It is generally accepted that decreased concentrations of THs could lead to delayed dental development in the child. Low levels of THs, not only during early childhood, but also during the mother’s pregnancy in cases where maternal hormonal deviations are present, have been related to delayed tooth maturation and tooth development in the child (Vucic et al., 2017).

Orthodontic considerations

Severe HT has detrimental effects on tooth eruption, leading to impacted permanent teeth due to prolonged maintenance of primary teeth with a consequent malocclusion (Bedi and Brook, 1984; Gupta et al., 2014; Ferrazo et al., 2014). Oral effects of HT also include enlargement of the tongue and lips, poor periodontal health, and delayed wound healing (Pinto and Glick, 2002; Gupta et al., 2014; Gecgelen Cesur et al., 2016). Hypothyroidism has been associated with root resorption during orthodontic tooth movement.

General characteristics

Hyperthyroidism refers to overproduction of THs from the thyroid gland, which results in high bone turnover and accelerated bone metabolism. The mean prevalence of hyperthyroidism in Europe is 0.75% (Garmendia Madariaga et al., 2014). Clinical manifestations include tremor, anxiety, intolerance of heat, sinus tachycardia, increased susceptibility to heart failure, and others (Chandna and Bathla, 2011). Grave’s disease is the most common disorder with clinical hyperthyroidism, together with pretibial swelling and exophthalmos.

Craniofacial and oral manifestations

Craniofacial and dental aspects of hyperthyroidism consist of maxillary or mandibular osteoporosis, increased susceptibility to caries, periodontal disease, accelerated dental eruption (Poumpros et al., 1994), and burning mouth syndrome (Pinto and Glick, 2002; Figure 5.4).

Orthodontic considerations

Bone metabolism has a significant impact on tissue reaction and consequently on tooth movement and retention period. Animal studies have resulted in differentiated tooth movement and bone resorption patterns in different bone metabolism groups (Verna and Melsen, 2003). In general, it is accepted that the orthodontic tooth movement rate may be higher in patients with hyperthyroidism.

General characteristics

Hyperparathyroidism (HPT) is characterized by oversecretion of PTH. It will result in hypercalcemia due to increased mobilization of calcium from bone to body fluids. HPT is categorized into the following types:

• Primary HPT, caused by parathyroid adenoma, gland hyperplasia, or carcinoma.
• Secondary HPT, which is the result of another medical condition producing hypocalcemia, such as rickets, osteomalacia, vitamin D deficiency, intestinal malabsorption syndrome, chronic renal insufficiency, or long‐term dialysis.
• Tertiary HPT, which arises from prolonged secondary HPT.
• A fourth type of HPT, because of an ectopic parathyroid gland, which occurs in patients with malignant diseases and adenomas.

Clinically, HPT shows great variation in signs and symptoms. Peptic ulcers, easy fatigue, a sense of weakness, depression, anxiety, and myocardial, valvular, and vascular calcification and neuropathy may be present (Ibrahem, 2020; Palla et al., 2018).

Craniofacial and oral manifestations

In HPT, changes in bone metabolism form localized bone cystic lesions known as “brown tumors” (Nair et al., 2011; dos Santos et al., 2018). Radiographically these appear as osteolytic radiolucent lesions (Figure 5.5). In the maxillofacial region most lesions affect the mandible, while fewer cases have been reported in the maxilla (Palla et al., 2018). In cases of multiple brown tumors, a differential diagnosis may be necessary (Ibrahem, 2020). Other oral findings include facial asymmetry or swelling, pulp stones, alterations in dental eruption and tooth position, malocclusions, periodontal ligament widening, delay in dental development, expansion of cortical bone, root resorption, displacement of roots, calcification of the soft tissue, dental caries, and oral, dental or bone pain (Kakade et al., 2015; Palla et al., 2018).

Orthodontic considerations

The clinical management of these patients requires special attention. Management of brown tumors is often directed toward the normalization of PTH levels through management of the underlying cause of HPT. A surgical approach may be necessary in some cases. There is a higher risk of bone fracture, so precautions must be taken in surgical interventions. The increased incidence of spontaneous root resorption in such patients may complicate orthodontic tooth movement. Before providing endodontic treatment, differential diagnosis is important as, in some cases, these lesions appear as a radiolucency in the periapical region of teeth and can lead to misdiagnosis of a lesion of pulpal origin (Venkatesh and Nandini, 2009). During the management of this disease and before the start of the orthodontic intervention, a multidisciplinary team approach will be helpful.

General characteristics