Accuracy of Static Computer- Assisted Implant Placement in Posterior Edentulous Areas with Different Levels of Tooth- Support by Novice Clinicians

Correct implant placement is necessary for satisfactory implant restoration. Therefore, the use of surgical guide is recommended. This study evaluated the accuracy of implant placement in posterior edentulous areas with different levels of tooth-support by novice clinicians according to fully-guided (FG), pilot-guided (PG), and freehand (FH) placement protocols. A mandibular model with missing first molars was designed. On one side, the model had a bound edentulous area (BEA), and on the other side, a free end edentulous area (FEA). Fourteen clinicians new to implant dentistry participated in the study, and each clinician inserted an implant in the BEA and FEA sites for every placement protocol. Angle, vertical and maximum horizontal platform and apex deviations were measured. The FG placement was more accurate than the PG and FH placements. This was significant for BEA angle deviation, BEA and FEA maximum horizontal platform deviations, and BEA maximum horizontal apex deviation. The PG placement was significantly more accurate than the FH placement for BEA and FEA maximum horizontal platform deviations. FG shows significantly greater angle, maximum horizontal platform and maximum horizontal apex deviations at FEA than BEA. This can be attributed to reduced guide support and the possibility of guide displacement during surgery.

Effect of Chairside CAD/CAM Restoration Type on Marginal Fit Accuracy: A Comparison of Crown, Inlay and Onlay Restorations

Chairside CAD/CAM is a convenient approach for fabricating dental restorations. However, the effect of CAD/CAM restoration type on marginal fit accuracy has not been fully investigated. This study evaluated of the marginal fit accuracy of 3 chairside CAD/ CAM restoration types (crown, inlay and onlay) using CEREC Bluecam (BC) and CEREC Omnicam (OC) scanners. Three artificial maxillary first molars received crown, inlay and onlay preparations. A total of 10 CAD/CAM ceramic restorations were produced for each tooth by each intraoral scanner. The marginal gap was measured along the preparation margin. For the BC, all the restorations had similar marginal gaps (crowns = 113.9 μm; inlays = 120.9 μm; onlays = 132.5 μm) (p = 0.20), while for the OC, the crowns (72.2 μm) and the inlays (74.9 μm) exhibited better marginal fit than the onlays (96.4 μm) (p = 0.003). For every restoration type, the OC provided a superior outcome compared with the BC. Therefore, the restoration type influenced the marginal gap, where the crowns tended to have the least marginal gap while the onlays had the greatest marginal gap. The newer scanner (OC) of the same manufacturer was more accurate than the older scanner (BC).

Accuracy of Intraoral Scanners: A Systematic Review of Influencing Factors

Digital impressions by intraoral scanning (IOS) have become an increasingly popular alternative to conventional impressions. This systematic review aimed to evaluate the accuracy of the available IOS systems for dental impression, and identify the influencing factors on accuracy. The literature search was completed to retrieve all the studies that investigated the IOS accuracy when used to scan teeth. A total of 2305 studies were initially obtained. After applying the inclusion criteria, 32 studies were suitable for the analysis. The following systems were included in the review: Cerec Bluecam, Cerec Omnicam, Cadent iTero, Lava C.O.S, Lava True Definition, TRIOS, TRIOS Color, E4D, Planscan, MHT, Carestream 3500 and Zfx IntraScan. In comparison to conventional impressions, the IOS systems can be reliably used for diagnostic purposes and short-span scanning. However, for whole arch scanning, the IOS is susceptible for more deviation. The studies indicated variable outcome of the different IOS systems. While the accuracy of IOS systems appears to be promising and comparable to conventional methods, they are still vulnerable to inaccuracies. For prosthesis fabrication, the IOS accuracy is enhanced by reducing the span of scanning, and ensuring the scanned surfaces exhibit minimal irregularities.

Determination of occlusal vertical dimension for complete dentures patients: an updated review

Determination of the occlusal vertical dimension (OVD) is an integral part of complete dentures fabrication. Due to the lack of teeth, the clinician faces the challenge of how to accurately establish the OVD of the new denture. Therefore, the purpose of this review article was to present, discuss and critique the available methods used in determining the OVD for complete dentures patients. This review identified two main streams to determine the OVD: (i) pre-extraction methods and (ii) post-extraction methods. For the pre-extraction methods, the OVD of the natural dentition is transferred to the new dentures mainly by intra-oral measurements, profile tracing and cephalometric analysis. The post-extraction methods rely on mandibular rest position, facial aesthetic appearance, swallowing pattern, craniofacial landmarks measurements, cephalometric analysis, phonetics and existing dentures. In general, all the available techniques have merits and are helpful for routine clinical use. However, they are empirical in nature, controversial and lack the scientific support. Further, there is no single accurate method for OVD determination. To overcome the limitations of the techniques, the clinician will benefit from applying combination of techniques to approximate the OVD.

Axial Tooth Contour Alteration Following Fixed Prosthodontic Treatment

This study evaluated the effect of crown restoration on the tooth labial axial contour. The pre-treatment and post-treatment models of 13 patients who underwent complex fixed prosthodontic treatment were obtained. All the models were converted to virtual models. Each post-treatment model was overlapped on the corresponding pre-treatment model to evaluate the contour alteration of the clinical crown. The contour of the crowned teeth significantly increased following the crown restoration treatment. The increase of the contour was directly proportional to the distance from the gingival margin. The anterior teeth had a significantly greater contour increase than the posterior teeth.

Oral health-related quality of life of removable partial denture wearers and related factors

This study aims to investigate the oral health-related quality of life (OHRQoL) in a group of removable partial denture (RPD) wearers in Shiraz (Iran), using the Persian version of the Oral Health Impact Profile (OHIP-14). Two hundred removable partial denture wearers had completed a questionnaire regarding patients' demographic characteristics and denture-related factors. In addition, the OHIP-14 questionnaire was filled out by interviewing the patients. Two measures of interpreting the OHIP-14 scales were utilised: OHIP-14 sum and OHIP-14 prevalence. The relationship of the patients' demographic characteristics and denture-related factors, with their OHRQoL was investigated. The mean OHIP-14 sum and OHIP-14 prevalence of RPD wearers were 13·80 (±10·08) and 44·5%, respectively. The most problematic aspects of OHIP-14 were physical disability and physical pain. Twenty-seven percentage and 24% of participants had reported meal interruption and eating discomfort, respectively. OHIP-14 prevalence and OHIP-14 sum were found to be significantly associated with factors representing RPD wearer's oral health such as self-reported oral health and frequency of denture cleaning. Furthermore, OHIP-14 prevalence and OHIP-14 sum were significantly associated with factors related to frequency of denture use such as hours of wearing the denture during the day and wearing the denture while eating and sleeping. Therefore, it can be concluded that the OHRQoL of the patients of the study was generally not optimal and found to be strongly associated with oral health.

Clinical considerations for increasing occlusal vertical dimension: a review

The purpose of this article is to discuss the clinical considerations related to increasing the occlusal vertical dimension (OVD) when restoring a patient's dentition. Thorough extraoral and intraoral evaluations are mandatory to assess the suitability of increasing OVD. In the literature, multiple techniques have been proposed to quantify OVD loss. However, the techniques lack consistency and reliability, which in turn affects the decision of whether to increase the OVD. Therefore, increasing OVD should be determined on the basis of the dental restorative needs and aesthetic demands. In general, a minimal increase in OVD should be applied, though a 5 mm maximum increase in OVD can be justified to provide adequate occlusal space for the restorative material and to improve anterior teeth aesthetics. The literature reflects the safety of increasing the OVD permanently, and although signs and symptoms may develop, these are usually of an interim nature. Whenever indicated, the increase in OVD should be achieved with fixed restorations rather than a removable appliance, due to the predictable patient adaptation. The exception to this is for patients with TMD, where increasing the OVD should still be achieved using removable appliances to control TMD-associated symptoms before considering any form of irreversible procedure.