A cephalometric study to investigate the skeletal relationships in patients with increasing severity of hypodontia

Abstract

Objectives: To determine the skeletal relationships in patients with hypodontia and analyze the effects of severity and pattern. Materials and Methods: Pretreatment lateral cephalograms from 277 patients with hypodontia, categorized by the number of missing teeth as mild (1-2), moderate (3-5), or severe ($6), were digitized recording angular measurements and ratios and compared with published norms matched for age and gender. Pattern was determined as mandibular, maxillary, bimaxillary, bilateral, anterior, posterior, and anteroposterior. Linear regression models assessed relationships between number of missing teeth and cephalometric parameters, controlling for the pattern of hypodontia. Results: For every additional missing tooth, SNA, SNB, and ANB decreased 0.3u, 0.1u, and 0.2u, respectively; this was clinically significant for .4, .10, and .5 missing teeth, respectively. Mandibular to cranial base ratio decreased 0.3% for every additional missing tooth; this was clinically significant for .10 missing teeth. The MMPA decreased 0.3u for every additional missing tooth; this was clinically significant for .7 missing teeth. Percentage LAFH decreased 0.2% for every additional missing tooth; this was significant for .7 missing teeth. Jarabak ratio increased 0.2% for each additional missing tooth; this was clinically significant for .10 missing teeth. Anterior hypodontia significantly decreased most cephalometric parameters. Conclusions:Patients with hypodontia demonstrated a tendency toward a Class III relationship, caused by decreased maxillary and mandibular angular prognathism and MnCB ratio, though the effect was greater on the maxilla than the mandible. Clinical significance was only associated with severe hypodontia. Vertically, there was a tendency toward decreased MMPA and %LAFH; this was clinically relevant only with severe hypodontia. Anterior hypodontia had a significant effect on skeletal relationship. (Angle Orthod. 2010;80:699-706.)

Variability in dentofacial phenotypes in four families with WNT10A mutations

“…So far it was accepted that the presence of the teeth themselves within the alveolar processes mechanically models the volume of the jaws. 12,25 Until recently, data suggestive for a possible molecular underpinning of this phenomenon was however lacking. In their study in mice, Cawthorn et al 26 identified Wnt10a as well as Wnt10b and Wnt6, as potent endogenous regulators of mesenchymal stem cell fate, inhibiting adipogenesis and stimulating osteoblastogenesis through a b-catenindependent mechanism.…”

“…12 Therefore, in addition to the description of the dental and general syndromic ED features, the aim in this study was to document the facial phenotypic variations in four families with WNT10A mutations and to give a comprehensive overview of the literature regarding WNT10A mutations, associated conditions and developmental defects.…”

Craniofacial morphology in individuals with increasing severity of hypodontia

“…A decrease in vertical jaw relation and mandibular plane inclination in persons with severe hypodontia was observed by Øgaard and Krogstad 25 and Nodal et al 30 Chung et al 31 and Acharya et al 32 found that severe hypodontia had a significant effect on a skeletal relationship.…”

“…24,25,[30][31][32] Ogaard and Krogstad 25 concluded that typical dentofacial structure in individuals with a larger number of absent teeth, is due to dental and functional adjustment rather than to an altered growth pattern, but Bondarets and Mc Donald, 24 in Table 2. Significantly reduced value of SNA angle in patients with different number of absent teeth determined in this study, is in compliance with findings of Wisth et al, 27 Roald et al, 35 Sarnäs and Rune 26 and Ogaard and Krogstad, 25 opposite to normal values of this parameter established of Woodworth et al, 23 Nodal et al, 30 Chung et al 31 and Yüksel and Ucem.…”

“…However, only a few authors have investigated the influence of different numbers of missing teeth on craniofacial morphology. 24,25,[30][31][32] Bondarets and Mc Donald 24 found that individuals with severe hypodontia had the typical facial characteristics unique to hypodontia, with reduced vertical dimensions.…”