A novel reference model for dental scanning system evaluation: analysis of five intraoral scanners.

PURPOSE: The aim of this in vitro study was to investigate the accuracy (trueness and precision) of five intraoral scanners (IOS) using a novel reference model for standardized performance evaluation. MATERIALS AND METHODS: Five IOSs (Medit i500, Omnicam, Primescan, Trios 3, Trios 4) were used to digitize the reference model, which represented a simplified full-arch situation with four abutment teeth. Each IOS was used five times by an experienced operator, resulting in 25 STL (Standard Tessellation Language) files. STL data were imported into 3D software (Final Surface®) and examined for inter- and intra-group analyses. Deviations in the parameter matching error were calculated. ANOVA F-test and Kruskal-Wallis test were applied for inter-group comparisons (α = .05); and the coefficient of variation (CV) was calculated for intra-group comparisons (in % ± SD). RESULTS: Primescan (matching error value: 0.015), Trios 3 (0.016), and Trios 4 (0.018) revealed comparable results with significantly higher accuracy compared to Medit i500 (0.035) and Omnicam (0.028) (P < .001). For intra-group comparison, Trios 4 demonstrated the most homogenous results (CV 15.8%). CONCLUSION: The novel reference model investigated in this study can be used to assess the performance of dental scanning technologies in the daily routine setting and in research settings.

Esthetic and functional outcomes of narrow-diameter implants compared in a cohort study to standard diameter implants in the anterior zone of the maxilla.

OBJECTIVE: The aim of this study was to evaluate functional and esthetic clinical outcomes and patient satisfaction with narrow-diameter implants in comparison to standard-diameter implants in the anterior zone of the maxilla in a follow-up examination after 1 to 6 years. METHOD AND MATERIALS: The study was designed as a retrospective cohort study investigation including 27 patients receiving a 3.3-mm diameter single implant (NDI, n = 14) or a standard-diameter 4.1-mm single implant in the anterior zone of the maxilla (SDI, n = 16). Descriptive and analytical statistics were performed comparing both groups with regard to clinical examination including esthetic outcome, sulcus fluid flow-rate, crown esthetics, patients' satisfaction on visual analog scales, occurrence of biologic or technical complication, probing pocket depths (Fisher exact test), pink esthetic score (PES) and Periotest (Mann-Whitney U test). The level of significance was set at α = .05. RESULTS: The mean observation period was 4.8 years after crown insertion in the NDI group, and 4.9 years in the SDI group. Significant differences were observed for Periotest values in favor of the 4.1-mm implants (P = .014). No differences were found with regards to esthetics (PES; P = .27) or sulcus fluid flow-rate (P = 0.73) and probing pocket depths (P = .35). Overall patient satisfaction was high for both groups with visual analog scale scores of 9.3 ± 1.1 for NDI and 9.4 ± 1.0 for SDI (P = .39). CONCLUSION: Clinical outcome with narrow-diameter implants was comparable to standard-diameter implants in the anterior zone of the maxilla with similar esthetic assessments and patients' satisfaction.

Surgical therapy of peri-implantitis with adjunctive hydroxyapatite and enamel matrix derivative: a 1-year retrospective case series.

This case series retrospectively investigated the one-year surgical outcome of regenerative peri-implantitis therapy using a hydroxyapatite (HA) bone substitute material in combination with enamel matrix derivate (EMD) and collagen membrane for guided bone regeneration (GBR). Data-sheets of patients were screened to detect patients who received identical regenerative peri implantitis-therapy with surface decontamination and GBR applying HA, EMD and a collagen membrane under broad- spectrum antibiotic regime. For inclusion, information on pre- and postoperative clinical and radiographic parameters (probing pocket depth (PPD), bleeding on probing (BOP), suppuration (SUPP) and the radiological bone level (RBL)) had to be available for statistical analysis. Data of a total of 11 patients (20 implants) were extracted out of 202 (336). All implants were still in function after one year. Bone defects decreased by an average of 1.3 mm mesially and 0.9 mm distally, respectively. Mean PPD was reduced from 4.9 mm to 2.7 mm. BOP decreased from 90% to 20%. Suppuration decreased from 65% to 0%. Based on the success criteria applied, 15 of the 20 (75%) implants included were considered as successfully treated after 1 year. Regenerative peri-implantitis therapy according to the presented concept showed promising clinical and radiographic outcomes after one year. To estimate the beneficial effects of the combined use of HA, EMD and collagen membranes, further long term investigations with a control group are needed.

Accuracy of a separating foil impression using a novel polyolefin foil compared to a custom tray and a stock tray technique.

PURPOSE: To compare the dimensional accuracy of three impression techniques- a separating foil impression, a custom tray impression, and a stock tray impression. MATERIALS AND METHODS: A machined mandibular complete-arch metal model with special modifications served as a master cast. Three different impression techniques (n = 6 in each group) were performed with addition-cured silicon materials: i) putty-wash technique with a prefabricated metal tray (MET) using putty and regular body, ii) single-phase impression with custom tray (CUS) using regular body material, and iii) two-stage technique with stock metal tray (SEP) using putty with a separating foil and regular body material. All impressions were poured with epoxy resin. Six different distances (four intra-abutment and two inter-abutment distances) were gauged on the metal master model and on the casts with a microscope in combination with calibrated measuring software. The differences of the evaluated distances between the reference and the three test groups were calculated and expressed as mean (± SD). Additionally, the 95% confidence intervals were calculated and significant differences between the experimental groups were assumed when confidence intervals did not overlap. RESULTS: Dimensional changes compared to reference values varied between -74.01 and 32.57 µm (MET), -78.86 and 30.84 (CUS), and between -92.20 and 30.98 (SEP). For the intra-abutment distances, no significant differences among the experimental groups were detected. CUS showed a significantly higher dimensional accuracy for the inter-abutment distances with -0.02 and -0.08 percentage deviation compared to MET and SEP. CONCLUSION: The separation foil technique is a simple alternative to the custom tray technique for single tooth restorations, while limitations may exist for extended restorations with multiple abutment teeth.

Partial Ceramic Crowns Prepared by Dental Students: Clinical Performance Up to Five Years.

Partial ceramic crowns (PCCs) are an accepted treatment option for the restoration of posterior teeth with deficient tooth substance. Data on the survival of PCCs fabricated by dental students are scarce. The aim of this retrospective clinical study was to investigate the clinical performance and longevity of PCCs placed by dental students in the last year of their training program at the University of Basel, Switzerland. Eighty-eight patients who had received at least one PCC (n=108) in the program were considered for clinical assessment; their records were analyzed to detect previous complications or failures; and they were contacted by telephone. Criteria regarding aesthetic, functional, and biological aspects were rated with a scoring system from 1=clinically excellent to 5=clinically poor. The response rate was 66.3% (55 of 83 included patients), and 72.2% (n=78) of the PCCs were included in the analysis. Five PCCs had been lost within ten to 78 months after treatment. Six PCCs were recorded as failures (score 5), and ten received clinically unsatisfactory gradings (score 4). The risk of a clinically poor outcome was 14% after five years (86% survival), while the overall success rate was 63.5%. These results suggest that the clinical procedure of PCCs was successfully implemented by these students with satisfactory clinical survival.

Technical accuracy of printed surgical templates for guided implant surgery with the coDiagnostiX ™ software.

BACKGROUND: Printing of templates for guided surgery represents an alternative to laboratory manufactured templates. PURPOSE: To determine the technical accuracy of a virtually designed and printed surgical template for guided implant surgery based on a surface scan of a cast model using the coDiagnostiX™ software. MATERIALS AND METHODS: Cast models and the virtual planning data of nine patients receiving guided implant surgery with the coDiagnostiX software were analyzed. The original cast models were equipped with three titanium pins and scanned with a three-dimensional scanner. The scans were uploaded in the coDiagnostiX software and the virtual surgical templates were designed including the sleeves at their original positions. After printing the surgical templates, the sleeve positions were determined by optical scanning, and deviations were calculated and compared with the virtual positions of the sleeves. RESULTS: The sleeves showed a mean three-dimensional deviation of 0.22 mm (range: 0.07-0.38 mm) in the center of the sleeve top, 0.24 mm (range: 0.08-0.36 mm) in the center of the sleeve bases and a mean angular deviation of 1.5° (range: 0.4°-3.3°) compared with the virtual positions. CONCLUSIONS: A high accuracy can be achieved using printed templates for guided implant surgery, by taking into account all sources of inaccuracies.

Periodontal surgery in furcation-involved maxillary molars revisited--an introduction of guidelines for comprehensive treatment.

Maxillary molars with interradicular loss of periodontal tissue have an increased risk of additional attachment loss with an impaired long-term prognosis. Since accurate clinical analysis of furcation involvement is not feasible due to limited access, morphological variations and measurement errors, additional diagnostics, e.g., with cone-beam computed tomography, may be required. Surgical treatment options have graduated from a less invasive approach, i.e., keeping as much periodontal attachment as possible, to a more invasive approach: (1) open flap debridement with/without gingivectomy or apically repositioned flap and/or tunnelling; (2) root separation; (3) amputation/trisection of a root (with/without root separation or tunnel preparation); (4) amputation/trisection of two roots; and (5) extraction of the entire tooth. Tunnelling is indicated when the degree of root separation allows for opening of the interradicular region. Alternatively, root separation is performed particularly in root-canal treated teeth with reduced coronal tooth substance requiring crown restorations. As soon as the attachment of one or two roots in maxillary molars is severely reduced, root removal is indicated and performed either as amputation or trisection including the corresponding part of the clinical crown. While the indication for regenerative measures in maxillary molars with furcation involvement is very limited, extraction and replacement with implants is restricted, particularly in sites requiring complex alveolar ridge augmentation and sinus elevation. A systematic approach for decision making in furcation-involved maxillary molars is described in this overview, including what constitutes accurate diagnosis and what indications there are for the different surgical periodontal treatment options.

Teledental consultations related to trauma in a Swiss telemedical center: a retrospective survey.

BACKGROUND/AIM: In addition to medical advice, telemedical centers also provide counseling on the telephone for patients with dental injuries. MATERIAL AND METHODS: Data from a Swiss telemedical center during the years 2001-2008 were analyzed retrospectively. RESULTS: A total of 371 988 medical consultations were recorded. Of these, 3430 concerned dental problems, with 672 reports about dental trauma following accidents with 772 injuries. The patients average age was 8.6 years (range 0-73 years). About two-thirds of the cases belonged to the age group 0-6 years, and one-third to the group of 7-80 years. The reasons for calling were dislocations (53%), fractures (31.9%), and avulsions (7.9%). In 76.2% of the cases, the center was contacted on the day of the accident. The majority of the patients (60%) contacted the telemedical center during the so-called 'out of office hours' (Monday to Friday 6 pm to 8 am, and Saturday/Sunday all day). CONCLUSIONS: Telemedicial services can be helpful for cases related to dental trauma and may provide valuable support when a dentist is not available.

[Frequency and manifestations of back pain in the dental profession]. / Häufigkeit und Auswirkungen von Rückenbeschwerden im zahnärztlichen Beruf.

Dentists, dental hygienists and dental assistants due to the nature of their work-related physical activity often have to deal with physical stress that will cause actual physical damage. The aim of the current survey was to analyse the frequency of job-related pain and associated impairment. The questionnaire for the cervical and lumbal region of the North American Spine Society was modified and used in the present investigation. Out of 6962 subjects, 2025 returned the questionnaire (response rate 34.5%). Between 20% and 36% of the participants suffered from pain in the cervical and lumbal region and were impaired in their daily activities, particularly during the lifting of objects, while standing or sleeping. Almost 40% of the dentists and 53% of the dental hygienists/dental assistants experienced problems related to perceived pain during or after dental treatments. More than half of the participants had already sought out medical help and/or physiotherapy due to job-related pain. The present data indicate that prophylactic and therapeutically based preventative measures should be encouraged in order to prevent cervical and back pain in this affected occupational group.

What is the prevalence of various types of prosthetic dental restorations in Europe?

OBJECTIVES: The aim of this review was to analyse the prevalence of prosthetic dental restorations in the adult population in Europe and to investigate factors influencing the frequencies of fixed restorations and removable dental prostheses (RDP). MATERIAL AND METHODS: A search for literature up to 31 October 2006 on dental restorations was performed in Medline via PubMed and in an additional hand search using several keywords related to epidemiology and dental restorations. Out of approximately 6000 titles listed, 136 articles were identified, which were related to 13 different European countries. 43 articles fulfilled the inclusion criteria and were included in this review. RESULTS: Approximately half of the adult population in most European countries have had some type of prosthetic dental restoration. The frequency of RDPs among adults varied between 13 and 29%, with 3-13% edentulous subjects wearing complete dentures in both jaws. The frequency of fixed restorations including crowns and fixed dental prostheses (FDPs, bridges) was the highest in Sweden with 45% and Switzerland (34%). In the recent decades, there has been a slight decrease in RDP use reflecting a decline in edentulism, while more subjects had maintained a residual dentition and were wearing removable partial dentures or fixed restorations. The latter are less prevalent in countries with lower prosperity. If only a few teeth are absent, these are generally replaced with FDPs or have no replacement. If more teeth are missing, the likelihood of a removable restoration increases with the number of teeth to be replaced. A higher frequency of removable restorations is present in older age groups, in subjects living in rural areas, in those from a lower socio-economic status and in subjects with less education and lower incomes. CONCLUSIONS: All types of fixed and removable restorations are highly prevalent, especially among older age groups, in most European countries. There is a trend towards higher frequencies of fixed restorations, more removable partial dentures and a reduction in complete dentures.

The ovate pontic design: a histologic observation in humans.

STATEMENT OF THE PROBLEM: Fixed partial dentures with an ovate pontic design contacting the underlying soft tissue may interfere with long-term mucosal health. PURPOSE: The purpose of this study was to examine the clinical and histologic characteristics of the human alveolar ridge mucosa adjacent to an ovate pontic-designed restoration. MATERIAL AND METHODS: Twelve patients requiring maxillary fixed partial dentures (either implant- or tooth-supported) with a pontic site in the premolar or molar region were studied. The pontics had an ovate design and were adapted to the underlying mucosa with tight but noncompressive contact. Patients used Super Floss once a day to clean the infrapontic area. After 12 months, soft tissue biopsy specimens about 3 x 3 mm in size were obtained (1) from the ridge mucosa in contact with the pontic (test site) and (2) from an adjacent uncovered masticatory mucosal area (control site). Histometrically, the thickness of the epithelium and the keratin layer and the height of the connective tissue papillae were measured. Morphometrically, the composition of the connective tissue of the specimens was analyzed in a 200-microm-wide zone immediately subjacent to the epithelium (zone A) and in a 200-microm-wide central connective tissue portion (zone B). A point-counting procedure was used to calculate the relative proportions occupied by collagen, fibroblasts, vascular structures, inflammatory cells, and residual tissue. Differences between the tissue fractions in test and control sites were analyzed with the Wilcoxon signed rank test (.05 level of significance). RESULTS: At 12 months, only 3 pontic sites showed clinical signs of mild inflammation, whereas the other test sites and all control sites appeared healthy. A thinner keratin layer was observed in pontic sites than in control sites (8 microm vs 22 microm). Larger tissue fractions of inflammatory cells were found in pontic sites than in control areas in the zone immediately subjacent to the epithelium. CONCLUSION: Within the limitations of this study, restoring an edentulous space with an ovate pontic supported by adequate oral hygiene measures was not associated with overt clinical signs of inflammation. Histologically, however, this pontic design was associated with a thinner keratin layer and with changes in the composition of the connective tissue compartment subjacent to the epithelium.

A review of clinical and technical considerations for fixed and removable implant prostheses in the edentulous mandible.

PURPOSE: The aim of the present article is to review some of the technical treatment options for implant prostheses restoring the edentulous mandible, mainly based on the Brånemark system. MATERIALS AND METHODS: Clinical and technical aspects are discussed for the three established concepts: (1) implant-supported fixed prosthesis, (2) removable implant-supported overdenture, and (3) combined implant-retained and soft tissue-supported overdenture prosthesis. RESULTS: The framework of an implant-supported fixed screw-retained prosthesis can be processed in gold, Co-Cr alloy, or titanium with casting, laser-welding, or milling techniques. To improve the stability and retention of a conventional complete denture, one to four implants are indicated, and unsplinted (single attachments) or splinted designs (bar systems) can be applied. The design of the overdenture prosthesis must be carefully planned according to the requirements to ensure adequate stability and optimal form, contour, and esthetics, and the patient's best comfort. CONCLUSION: A large variety of different treatment modalities exist for both the fixed and removable mandibular implant prosthesis. Clinical and technical aspects should be considered at the beginning of the treatment to: (1) select the optimal implant position, (2) establish an adequate number of functional units, (3) select the appropriate retainers, and (4) apply the best technique for framework processing and veneering.