Enhancing intraoral scanner accuracy using scan aid for multiple implants in the edentulous arch: An in vivo study.

OBJECTIVES: Intraoral scans of multiple implants in the edentulous arch are challenged by the absence of a distinct surface morphology between scan bodies. A scan aid was applied in such situation and evaluated for intraoral scanning accuracy in vivo. MATERIALS AND METHODS: 87 implants in 22 patients were scanned with scan aid (SA) and without scan aid (NO) using two different intraoral scanners (CS3600 [CS] and TRIOS3 [TR]). Master casts were digitized by a laboratory scanner. Virtual models were superimposed using an inspection software and Linear deviation and precision were measured. Statistical analysis was performed using linear mixed models (α = .05). RESULTS: Total mean linear deviation within the CS group was 189 µm without scan aid and 135 µm when using the scan aid. The TR group's total mean deviation was 165 µm with and without a scan aid. Significant improvement with scan aid was observed for the CS group (p = .001), and no difference was found in the TR group. 96% of scan bodies were successfully scanned in the TR-SA group compared to 86% for the TR-NO group, 83% for the CS-SA, and 70% for the CS-NO group, respectively. CONCLUSIONS: The evaluated scan aid improved linear deviation compared to unsplinted scans for the CS group but not for the TR group. These differences could originate from different scanning technologies used, active triangulation (CS) and confocal microscopy (TR). The scan aid improved the ability to recognize scan bodies successfully with both systems, which could have a favorable clinical impact overall.

Accuracy of intraoral scans: An in vivo study of different scanning devices.

STATEMENT OF PROBLEM: The accuracy of intraoral scanners is a prerequisite for the fabrication of dental restorations in computer-aided design and computer-aided manufacturing (CAD-CAM) dentistry. While the precision of intraoral scanners has been investigated in vitro, clinical data on the accuracy of intraoral scanning (IOS) are limited. PURPOSE: The purpose of this clinical study was to determine the accuracy of intraoral scanning with different devices compared with extraoral scanning. MATERIAL AND METHODS: An experimental appliance was fabricated for 11 participants and then scanned intraorally and extraorally with 3 different intraoral scanners and a reference scanner. Intraoral and extraoral scans were subdivided into complete-arch and short-span scans and compared with the reference scan to assess trueness. Repeated scans in each group were assessed for precision. RESULTS: Precision and trueness were higher for extraoral scans compared with intraoral scans, except for complete-arch scans with 1 intraoral scanner. The median precision of short-span scans was higher (extraoral: 22 to 29 µm, intraoral: 23 to 43 µm) compared with complete-arch scans (extraoral: 81 to 165 µm, intraoral: 80 to 198 µm). The median trueness of short-span scans (extraoral: 28 to 40 µm, intraoral: 38 to 47 µm) was higher than that of complete-arch scans (extraoral: 118 to 581 µm, intraoral: 147 to 433 µm) for intraoral and extraoral scanning. CONCLUSIONS: Intraoral conditions negatively influenced the accuracy of the scanning devices, which was also reduced for the complete-arch scans.

Dentofacial Composition: An Entire Aesthetic Concept.

The aesthetic appearance of the mouth region, in addition to the eye and nose area, is the impressive element for facial aesthetics. Therefore, the reconstruction of the intraoral region is very important for the facial aesthetics in the case of genetic dysplasia, trauma, or even in cases for rejuvenating purposes only. The entire region is complex so that in many patient cases only the team work of restorative dentists, surgeons, and orthodontists will be effective. A key role is played here by the dental technician. Besides the frequent necessity of osseous augmentation, the mucogingival complex needs to be, in most cases, harmonized and reconstructed, respectively. There is often a lack of keratinized gingiva and disturbing cicatrice tracks. Quite frequently the mucogingival appearance is also unsatisfactory due to preceding operations and attempted plastic coverages. The aim of this report is to describe the successful surgical and prosthetic treatment of aesthetically and functionally impaired intraoral hard and soft tissue. For surgeons who are interested in aesthetics, it is advisable to learn from experiences of a specialized restorative dentist, oral surgeon, and orthodontist.

The Influence of Torque Tightening on the Position Stability of the Abutment in Conical Implant-Abutment Connections.

The influence of repeated system-specific torque tightening on the position stability of the abutment after de- and reassembly of the implant components was evaluated in six dental implant systems with a conical implant-abutment connection. An established experimental setup was used in this study. Rotation, vertical displacement, and canting moments of the abutment were observed; they depended on the implant system (P = .001, P < .001, P = .006, respectively). Repeated torque tightening of the abutment screw does not eliminate changes in position of the abutment.

Analysis of soft tissue display during enjoyment smile. Part II: elder Caucasians.

Esthetic parameters in elder patients are essential in esthetic oral rehabilitation. To date, no study has quantified the amount and frequency of soft tissue display in the papilla area in patients over 50 years of age. Photographic examination of 42 fully dentate patients with a mean age of 59 years was performed during enjoyment smile. Digital processing and measurement of the tooth, gingiva, and papilla display revealed that over 90% of subjects displayed soft tissue in the papilla area of the anterior teeth and first premolar during enjoyment smile regardless of their sex. The frequency of the display in descending order follows: maxillary lateral incisor (96%), central incisor (94%), canine (94%), first premolar (91%), second premolar (85%), and first molar (39%). The mean amount of papilla display was 3.4 mm (0 to 10 mm). There was no significant difference in the amount of papilla display between sexes for anterior teeth, premolars, or first molar (P = .97, P = .79, and P = .48, respectively). Elder caucasians showed significantly less gingiva in the area of the premolars and molars but not in the anterior region. The amount of papilla display is significantly less in elder caucasians in the anterior and premolar region. The mean amount of soft tissue display decreased with age but the frequency of papilla display was more than 90% in the anterior region and greater than 70% in the premolar region, suggesting that pink esthetics is an issue in patients over 50 years of age.

Impact of abutment rotation and angulation on marginal fit: theoretical considerations.

PURPOSE: Rotational freedom of various implant positional index designs has been previously calculated. To investigate its clinical relevance, a three-dimensional simulation was performed to demonstrate the influence of rotational displacements of the abutment on the marginal fit of prosthetic superstructures. MATERIALS AND METHODS: Idealized abutments with different angulations (0, 5, 10, 15, and 20 degrees) were virtually constructed (SolidWorks Office Premium 2007). Then, rotational displacement was simulated with various degrees of rotational freedom (0.7, 0.95, 1.5, 1.65, and 1.85 degrees). The resulting horizontal displacement of the abutment from the original position was quantified in microns, followed by a simulated pressure-less positioning of superstructures with defined internal gaps (5 µm, 60 µm, and 100 µm). The resulting marginal gap between the abutment and the superstructure was measured vertically with the SolidWorks measurement tool. RESULTS: Rotation resulted in a displacement of the abutment of up to 157 µm at maximum rotation and angulation. Interference of a superstructure with a defined internal gap of 5 µm placed on the abutment resulted in marginal gaps up to 2.33 mm at maximum rotation and angulation; with a 60-µm internal gap, the marginal gaps reached a maximum of 802 µm. Simulation using a superstructure with an internal gap of 100 µm revealed a marginal gap of 162 µm at abutment angulation of 20 degrees and rotation of 1.85 degrees. The marginal gaps increased with the degree of abutment angulation and the extent of rotational freedom. CONCLUSIONS: Rotational displacement of the abutment influenced prosthesis misfit. The marginal gaps between the abutment and the superstructure increased with the rotational freedom of the index and the angulation of the abutment.