Objective The objectives of this study were to evaluate the effect of a CAD/CAM nickel‐titanium retainer on the stability of mandibular anterior teeth and periodontal health and to compare it with other retainers. Setting/Sample Population Sixty participants from both genders who had irregularities prior to orthodontic therapy and who had been treated with full‐fixed appliance mechanotherapy were included in the study and randomly allocated into four groups: CAD/CAM NiTi, multi‐stranded stainless steel, single‐stranded nickel‐free titanium and vacuum‐formed removable retainer groups. The mean age of the participants at the end of the treatment was approximately 20 years. Materials and Methods Digital impressions were taken for all participants at three different times: immediately (T0), three months (T1) and six months (T2) after treatment. Irregularity index, inter‐canine and inter‐molar width, and arch length were recorded using software. Additionally, a full periodontal assessment was carried out at T2. Results During the follow‐ups, all groups showed some relapse in the lower anterior teeth. No statistical significance was found intergroup in terms of all measured values. Within the multi‐stranded group, inter‐canine width had decreased by 0.10 mm with a statistical significance (P = .048). An additional statistical significance with P = .045 was found within the single‐stranded group regarding the increased arch length. The periodontal assessment results of the mandibular anterior teeth between groups did not show clinically significant differences. Conclusion No statistical significance was found between the CAD/CAM retainer and other retainers regarding the clinical failure rate. Less plaque accumulation and gingival inflammation were observed in the CAD/CAM NiTi retainer group.

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Objectives The aim of this investigation was to evaluate the dental and craniofacial characteristics of subjects with amelogenesis imperfecta (AI) using lateral cephalometric radiography. Methods The sample consisted of the lateral cephalometric radiographs of 20 AI patients, irrespective of orthodontic malocclusion, and 18 healthy control subjects. Commonly used cephalometric measurements (8 linear, 6 angular) were compared between groups. Differences were tested with analysis of variance and Duncan's test. Intraclass correlation coefficients were used to examine intraobserver reliability. Results The AI group displayed significant differences from the control group, indicating a tendency towards a skeletal open-bite malocclusion (p \ 0.01). Despite the random selection of AI cases, the mean intermaxillary relationship of the AI group fell within the Class I malocclusion type. The AI group showed increased anterior facial height (p \ 0.01) and decreased posterior facial height (p \ 0.01) in comparison with the control group. No significant difference was found in maxillary or mandibular effective lengths. Conclusions Open-bite malocclusion was found in 35% of patients with AI. The mean vertical dimensions were increased in the AI group. These characteristics are considered to be skeletal in origin, although the etiological relationship between AI and skeletal disharmony remains unknown.

Paranasal sinuses located in the bones surrounding the nasal cavity are called maxillary, ethmoid, frontal and sphenoid sinuses. In relation with their location, these sinuses contribute to the development of the facial structures, jaws and upper airway. During the developmental process of the paranasal sinuses, anatomic variations can occur in consequence of intra and extramural migration of the ethmoid air cells, overpneumatization or hypoplasia of the sinuses and bulging of the neurovascular structures to the sinuses. Some of these anatomic variations may affect the drainage pathways, pave the way for chronic infections and cause difficulties when performing paranasal sinuses surgery.Therefore, the aim of this chapter was to examine the paranasal sinus anatomic variations with cone beam computed tomography (CBCT).

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