Posterior partially edentulous jaws, planning a rehabilitation with dental implants

AIM: To discuss important characteristics of the useof dental implants in posterior quadrants and the rehabilitation planning. METHODS: An electronic search of English articles was conducted on MEDLINE(PubM ed) from 1990 up to the period of March 2014. The key terms were dental implants and posterior jaws, dental implants/treatment planning and posterior maxilla, and dental implants/treatment planning and posterior mandible. No exclusion criteria were used for the initial search. Clinical trials, randomized and non randomized studies, classical and comparative studies, multicenter studies, in vitro and in vivo studies, case reports, longitudinal studies and reviews of the literature were included in this review. RESULTS: One hundred and fifty-two articles met the inclusion criteria of treatment planning of dental implants in posterior jaw and were read in their entirety. The selected articles were categorized with respect to their context on space for restoration, anatomic considerations(bone quantity and density), radiographic techniques, implant selection(number, position, diameter and surface), tilted and pterygoid implants, short implants, occlusal considerations, and success rates of implants placed in the posterior region. The results derived from the review process were described under several different topic headings to give readers a clear overview of the literature. In general, it was observed that the use of dental implants in posterior region requires a careful treatment plan. It is important that the practitioner has knowledge about the theme to evaluate the treatment parameters. CONCLUSION: The use of implants to restore the posterior arch presents many challenges and requires a detailed treatment planning.

Effects of Denture Removal on Expiratory Upper Airway Patency during Mask Ventilation in Complete Denture Wearers under General Anesthesia

Background: Some anesthetized patients present with expiratory airway obstruction (EAO) during mask ventilation (MV). EAO may occur more frequently among edentulous patients for whom a firmer grip of the mask and the mandible is needed to avoid gas leakage. We compared EAO grades before and after denture removal and identified predictors of EAO during MV in edentulous patients. Methods: One hundred and eight denture-wearing edentulous patients were anesthetized, their mouths were wrapped with film, their nasal masks and mandibles were held with two hands, and their lungs were ventilated in a pressure-controlled mode. Their dentures were subsequently removed, mouths were re-wrapped, and nasal MV was reapplied. EAO was graded based on capnography waveforms as follows: Grade I, normal waveform (no obstruction);II, loss of the alveolar plateau of the waveform (partial obstruction);and III, no waveform (total obstruction). EAO grades were compared before and after denture removal. Predictive demographic variables for occurrence of total EAO were identified using a multivariate analysis. Results: The proportions of Grades I, II, and III were 43.5%, 26.9%, and 29.6% when dentures were worn and 35.2%, 15.7%, and 49.1%, respectively, when dentures were removed. A significant difference was observed in EAO grades before and after denture removal (P = 0.000034). Age ≥ 75 years (adjusted odds ratio 3.41;95% confidence interval 1.31 - 8.87;P = 0.012) and body mass index ≥ 25 kg/m2 (adjusted odds ratio 2.61;95% confidence interval 1.07 - 6.40;P = 0.036) were independently associated with an increased incidence of total EAO in patients with their dentures removed. Conclusion: Denture removal impaired expiratory upper airway patency in edentulous patients, particularly in older or obese patients, during MV.

Measurement of Mucosal Thickness in Denture-bearing Area of Edentulous Mandible

Background： The thickness of the alveolar mucosa influences the probability of the occurrence of denture-induced irritations. Thick denture-supporting tissues offer relief from mucosal tenderness and ulcers; however, the uniformity of the thickness across the entire mandibular alveolar mucosa cannot be accurately determined in edentulous patients. This study aimed to assess the mucosal thickness of the denture-bearing area in the edentulous mandible. Methods： Twenty-seven edentulous patients underwent cone-beam computed tomography scanning, wherein the patients wore a record base to retract soft tissues away from the alveolar mucosa. The measured regions were the central incisor （1C）, lateral incisor （1L）, canine （Ca）, first premolar （P 1）, second premolar （P2）, first molar （M 1）, and second molar （M2） regions. The thickness was measured in the alveolar ridge crest （T）, buccal （B1-B4）, and lingual （L I-L4） alveolar ridge mucosa. The average thickness of the mucosa at buccal sides （B） and lingual sides （L） were also assessed. Results： The differences in the mucosal thickness between the left and right sides were not significant. In the Ca-M2 regions, T was the thickest, and L3 was the thinnest of all the measured points in the same regions. L was significantly less than B in posterior regions （P 〈 0.01 ）. On the other hand, M2 at L4 was thinnest of all the measured regions from Ca to M2 （P 〈 0.01）, and was thicker than IC, IL, P1, and P2 at B2. Conclusions： Since the mucosal thickness of denture-bearing area in the edentulous mandible is not uniform; the tissue surface of the denture base or custom tray should be selectively relieved, which may reduce the risk of denture-induced irritations.