Compared with the frequent investigations into the accuracy of digital intraoral scans, studies analyzing digital determinations of jaw relationships based on intraoral scans are scarce.
The purpose ...of this in vitro study was to present an optical 3-dimensional method for analyzing deviations in static occlusion and to compare the accuracy of conventional and digital interocclusal registrations.
A Frasaco jaw model was duplicated, articulated, and scanned with a high-precision industrial scanner, and the data were stored in a virtual standard tessellation language (STL) format, which served as the reference model. Fifteen paired mandibular and maxillary models were scanned with a digital intraoral scanner in the completely digital workflow (IOS group). Forty-five paired gypsum casts were poured from polyvinyl siloxane (PVS) impressions and associated with 2 different PVS registration materials. These casts were digitized with a laboratory scanner and grouped as follows (n=15/group): PVS group, conventional Futar D interocclusal record; sPVS group, conventional Futar Scan interocclusal record; and the AIR group, partially digital antagonist scan of the Futar Scan interocclusal record. The axes (X, Y, Z, and XYZ) of each paired model were aligned to those of the reference model by 3-dimensional superimposition, and deviations were calculated. To determine the ideal zero position, a best-fit over the mandibular teeth between the reference model and the actual model was estimated. Next, a second best-fit was determined between the maxillary models to determine the actual position of the mandibular model. The different registration methods were compared with the Mann–Whitney U test (α=.05).
In the IOS group, the interocclusal registration caused a mandibular deviation of 0.05 ±0.04 mm (mean ±standard deviation). This fit was better than those of conventional registrations with inserted interocclusal registration materials (PVS group and sPVS group), which caused mean z-axis deviations of 0.41 ±0.46 mm and 0.44 ±0.32 mm (P<.001), with the deviations leading to elevation of the mandibular model. The partially digital workflow with a scannable registration material (AIR group) showed significantly larger deviations in the x-axis (0.15 ±0.08 mm; P=.042) compared with the IOS group. No significant difference was observed in the total deviation between the IOS and the AIR groups. Both groups showed significantly smaller deviations than the conventional registration methods (P<.001 for the IOS group and P=.023 for the AIR group).
In comparison with maxillary and mandibular alignment using conventional interocclusal registration materials, digital interocclusal registrations showed greater accuracy in evaluating complete jaw models and can be recommended for clinical use. Additionally, the partially digital workflow with an antagonist scan of the interocclusal record provided acceptable results.
Objectives/Hypothesis:
In the treatment of burning mouth syndrome (BMS), various approaches have been tried with equivocal results. The aim of the present randomized clinical trial was to determine ...the efficacy of clonazepam, a GABA agonist designed as an antiepileptic drug that exerts the typical effects of benzodiazepines.
Study Design:
Randomized clinical trial.
Methods:
Twenty patients with idiopathic BMS were carefully selected. Clonazepam (0.5 mg/day, n = 10) or placebo (lactose, n = 10) were randomly assigned to the patients.
Results:
Patients on clonazepam significantly improved in pain ratings (P < .001). These changes were less pronounced in the placebo group (P < .11). No significant changes were observed in a mood scale (P = .56) or for depression scores (P = .56). Taste test and salivary flow increased over sessions, but were not different between groups (P = .83 and P = .06, respectively).
Conclusions:
Clonazepam appears to have a positive effect on pain in BMS patients. Laryngoscope, 2012
The esthetic outcome of dental implants can be compromised when some degree of bone loss occurs around the implant. This may particularly affect the tissue-level (TL) design. Therefore, bone-level ...(BL) design implants may be preferable if a natural emergence profile is important. Notwithstanding the implant design, the gingival biotype has been identified as a crucial factor in the stability of crestal bone. The objective of this study was to investigate bone loss in patients with different gingival biotypes at TL and BL implant sites in the esthetic zone.
In 41 patients, 20 TL and 22 BL implant procedures were carried out. Intraoral radiographs of all of the 42 sites were taken immediately after implant insertion as well as during the follow-up examination. The analysis of bone height was conducted using a computerized technique. The TRAN method was used to determine the gingival biotype.
After a mean in situ period of 4.9 years in the TL group, 12 implants with a thick biotype had a mean bone loss of 0.21 mm (SD: 0.43 mm). The eight implants with a thin biotype had a loss of 0.05 mm (SD: 0.47 mm; P = .31). After a mean in situ period of 1.9 years, the 14 BL sites with a thick biotype showed a mean bone change of -0.03 mm (SD: 0.38 mm). In the eight implants with a thin biotype, a change of +0.09 mm (SD: 0.32 mm; P = .84) was noted.
Analysis of the obtained results did not reveal a dependency of bone height on implant design or on gingival biotype. However, prior to choosing an implant design, it may nevertheless be beneficial to screen for transparent soft tissues, where the BL design offers a more natural emergence profile. For this purpose, the TRAN method is clearly the fastest and easiest.
The aim of this study was to assess and compare the esthetic outcome of tissue-level (TL) and bone-level (BL) implants that had been placed as single implants in the anterior maxilla.
Between 2001 ...and 2008, patients were treated using TL implants (Straumann). From 2008 until 2012, patients received the newly developed BL implant (Straumann). All patients with a single anterior maxillary implant who came to check-ups regularly were contacted and invited to take part in the study. Standardized photographs were taken to conduct the evaluation. Five observers analyzed the esthetic outcome using the pink esthetic score (PES). For the purpose of statistical analysis, the Wilcoxon rank sum test was applied. Interobserver reliability was evaluated with Krippendorff's alpha.
Forty-six patients agreed to take part in the study. The study comprised 10 immediate (TL = 6, BL = 4), 21 early (TL = 6, BL = 15), and 15 delayed implantations (TL = 11, BL = 4). All implant sites were simultaneously augmented. The prosthetic restorations were delivered 6 to 24 weeks after implant placement in the TL group and 10 to 14 weeks after implant placement in the BL group. Esthetic evaluation was performed after a mean period of 9.5 years for TL implants (range: 5.5 to 12.0) and 3.7 years for BL implants (range: 2.6 to 7.1). The overall PES was 8.49 (SD: 2.35) for TL implants and 9.29 (SD: 1.90) for BL implants (P = .37). Comparison of single parameters was between P = .24 and P = .83, indicating no statistically significant difference between the two implant types.
Within the limits of this study, it can be stated that both implant designs showed comparably satisfying esthetic results.
The aim of this study was to compare the trueness of complete- and partial-arch impressions obtained using conventional impression materials and intraoral scanners in vivo. Full-arch impressions were ...taken using polyether and polyvinylsiloxane. Gypsum casts were digitized using a laboratory scanner (IM, AF). Casts obtained from polyether impressions were also scanned using an industrial blue light scanner to construct 3D reference models. Intraoral scanning was performed using CEREC Omnicam (CO) and Trios 3 (TR). Surface matching software (Atos Professional) enabled to determine the mean deviations (mean distances) from the reference casts. Statistically significant discrepancies were calculated using the Wilcoxon signed-rank test. The mean distance for trueness ranged from 0.005 mm (TR) to 0.023 mm (IM) for the full arch, from 0.001 mm (CO) to 0.068 mm (IM) for the anterior segment, and from 0.019 mm (AF) to 0.042 mm (IM) for the posterior segment. Comparing the anterior vs. the posterior segment, significantly less deviations were observed for anterior with CO (p < 0.001) and TR (p < 0.001). Full-arch comparisons revealed significant differences between AF vs. IM (p = 0.014), IM vs. CO (p = 0.002), and IM vs. TR (p = 0.001). Full-arch trueness was comparable when using Affinis and the two intraoral scanners CEREC Omnicam and Trios 3. The digital impression devices yielded higher local deviations within the complete arch. Digital impressions of the complete arch are a suitable and reliable alternative to conventional impressions. However, they should be used with caution in the posterior region.Trial registration: Registration number at the German Clinical Trial Register (04.02.2022): DRKS00027988 ( https://trialsearch.who.int/ ).
The marginal accuracy of fit between prosthetic restorations and abutment teeth represents an essential aspect with regard to long-term clinical success. Since the final gap is also influenced by the ...luting techniques and materials applied, this study analyzed the accuracy of the fit of single-tooth zirconia copings before and after cementation using different luting materials. Forty plaster dies with a corresponding zirconia coping were manufactured based on a single tooth chamfer preparation. The copings were luted on the plaster dies (
= 10 per luting material) with a zinc phosphate (A), glass-ionomer (B), self-adhesive resin (C), or resin-modified glass-ionomer cement (D). The accuracy of fit for each coping was assessed using a non-destructive digital method. Intragroup statistical analysis was conducted using Wilcoxon signed rank tests and intergroup analysis by Kruskal-Wallis and Mann-Whitney U tests (α = 0.05). Accuracy of fit was significantly different before/after cementation within A (0.033/0.110 µm) and B (0.035/0.118 µm;
= 0.002). A had a significantly increased marginal gap compared to C and D, and B compared to C and D (
≤ 0.001). Significantly increased vertical discrepancies between A and B versus C and D (
< 0.001) were assessed. Of the materials under investigation, the zinc phosphate cement led to increased vertical marginal discrepancies, whereas the self-adhesive resin cement did not influence the restoration fit.
Stress distribution and its magnitude during loading heavily influence the osseointegration of dental implants. Currently, no high-resolution, three-dimensional method of directly measuring these ...biomechanical processes in the peri-implant bone is available. The aim of this study was to measure the influence of different implant materials on stress distribution in the peri-implant bone. Using the three-dimensional ARAMIS camera system, surface strain in the peri-implant bone area was compared under simulated masticatory forces of 300 N in axial and non-axial directions for titanium implants and zirconia implants. The investigated titanium implants led to a more homogeneous stress distribution than the investigated zirconia implants. Non-axial forces led to greater surface strain on the peri-implant bone than axial forces. Thus, the implant material, implant system, and direction of force could have a significant influence on biomechanical processes and osseointegration within the peri-implant bone.
Summary Purpose The purpose of this study was to assess the accuracy of implant placement after virtual planning of implant positions using cone-beam CT data and surgical guide templates, and to ...match the results with those achieved with the conventional free-hand method. Materials and methods Twenty-three implants were placed in 10 patients with a Kennedy Class II with 3-dimensional (3-D) planned surgical guide template. Manual implantation was performed in anatomical casts of the same patients by a prosthodontist and a maxillofacial surgeon. Postoperative images of casts were superimposed onto the preoperative image of virtual planned ideal position of the implant. Results The 3-D surgical guide template produced significantly smaller variation between the planned and actual implant positions at the implant shoulder (0.9 mm (0–4.5)) and apex (0.6–0.9 mm (0.0–3.4)) compared with the free-hand implantation (2.4–3.5 mm (0.0–7.0); p = 0.000 and 2.0–2.5 mm (0.0–7.7); p = 0.002). Accuracy of axis was also significantly improved. Conclusions Accuracy of implant placement after virtual planning of implant position using cone-beam CT data and surgical templates is high and significantly more accurate than free-hand insertion. The demonstrated method of superimposing radiographic images of postoperative casts and virtual planning images is a useful method, which allows reduced patient radiation exposure.
Aim
The objective of this randomized clinical trial was to investigate the influence of the time of implant placement (immediate vs. early) and the time of restoration (immediate vs. early) on ...esthetic outcome in maxillary anterior single implants.
Material and methods
Forty‐eight patients with a single failing incisor in the maxilla and a natural contralateral site were randomly distributed into four groups. Treatment variations affected the time of implant placement (immediate or early) as well as the time of restoration (immediate or early) – in detail, group 1a with immediate implant placement and immediate temporary restoration, group 1b with immediate implant placement and early restoration, group 2a with early implant placement and immediate temporary restoration, and group 2b with early implant placement and early restoration. All patients received the final prosthetic restoration 10–12 weeks after implant placement. Standardized photographs were taken eight months after tooth extraction. Five competent observers analyzed the esthetic outcome according to the PES after Fürhauser. For statistical analysis, the Kruskal–Wallis test and Dunn's post hoc test were applied. Interobserver reliability was evaluated by Krippendorff's alpha.
Results
The overall scores of the four treatment groups revealed PES values of 8.47 (SD 2.08, group 1a), 7.93 (SD 3.21, group 1b), 6.62 (SD 3.24, group 2a), and 8.10 (SD 3.25, group 2b). The differences between groups 2a and 1a and between groups 2a and 2b were statistically significant (P = 0.015 and P = 0.047). The single parameter analysis displayed a certain range of fluctuation and heterogeneity.
Conclusions
Immediate implant placement and restoration appear to be a viable alternative to early implant placement if an experienced surgeon is entrusted with the implantation procedure.
Abstract
Background
In mucogingival and implant surgery, an autologous soft tissue graft from the palate is the gold standard for reconstructing missing keratinised soft tissue and volume. ...Previously, presurgical measurements of the graft harvesting site were described with two-dimensional (2D) linear measurements. The present observational clinical study aimed to evaluate a three-dimensional (3D) measurement method for determining the present palatal soft tissue volume for each patient individually.
Methods
Pre-existing cone beam computed tomography (CBCT) scans of 20 patients were converted into 3D Standard Tessellation Language models of the bone surface. Intraoral impressions of the maxilla were taken and digitised to visualise the gingival surface. The resulting virtual models of bone (reference value) and gingival (actual value) surfaces were merged, with tooth surfaces used for registration. The region between the central incisors and the hard palate was subdivided into 5 regions of interest (ROIs). The distance between palatal bone and gingival surface was analysed both volumetrically and linearly, and the results were statistically evaluated for the ROIs.
Results
The average gingival surface area on the palate was 19.1 cm
2
, and the mean volume was 58.2 cm
3
(± 16.89). Among the ROIs, the mean linear value was highest in the most distal region, from the second molar to the hard palate (4.0 ± 1.09 mm) and lowest in the canine region (1.9 ± 0.63 mm). For mean distance, significant differences were found for the anterior palate and the most posterior palate in comparison with all other ROIs (
p
< 0.01). The volume measurements also declined significantly and steadily between the posterior (1.9 ± 1.0 cm
3
) and anterior palates (0.4 ± 0.2 cm
3
).
Conclusions
By merging digital data, palatal soft tissue could be quantified virtually. The results were reliable and comparable to previous findings with linear measurement methods. This 3D soft tissue volume analysis method fully exploited the diagnostic potential of data that are frequently collected for presurgical planning in oral surgery (i.e., CBCT + surface scans). This evaluation method might be useful for volumetric and linear measurements in other applications in anatomy and for determining palatal soft tissue dimensions in the planning stage before surgical interventions.
Trial registration
This observational clinical trial was retrospectively registered in the German Clinical Trials Register, reference number: DRKS00023918.
