Influence of oral motor tasks on postural muscle activity during dynamic reactive balance

BACKGROUND

Jaw clenching improves dynamic reactive balance on an oscillating platform during forward acceleration and is associated with decreased mean sway speed of different body regions.

OBJECTIVE

It is suggested that jaw clenching as a concurrent muscle activity facilitates human motor excitability, increasing the neural drive to distal muscles. The underlying mechanism behind this phenomenon was studied based on leg and trunk muscle activity (iEMG) and co-contraction ratio (CCR).

METHODS

Forty-eight physically active and healthy adults were assigned to three groups, performing three oral motor tasks (jaw clenching, tongue pressing against the palate or habitual lower jaw position) during a dynamic one-legged stance reactive balance task on an oscillating platform. The iEMG and CCR of posture-relevant muscles and muscle pairs were analysed during platform forward acceleration.

RESULTS

Tongue pressing caused an adjustment of co-contraction patterns of distal muscle groups based on changes in biomechanical coupling between the head and trunk during static balancing at the beginning of the experiment. Neither iEMG nor CCR measurement helped detect a general neuromuscular effect of jaw clenching on the dynamic reactive balance.

CONCLUSION

The findings might indicate the existence of robust fixed patterns of rapid postural responses during the important initial phases of balance recovery.

Comparison of the accuracy of different types of bite recordings - an in vitro study

OBJECTIVES

Reconstruction of a three-dimensional jaw position determined by a bite recording is an important aspect of prosthetic therapy. Different materials are used for this purpose. In the dental technical workflow, recordings are used to mount a lower jaw cast in a patient-like spatial position relative to the upper jaw cast. We evaluated the accuracy of positioning under the influence of different jaw positions and materials.

MATERIALS AND METHODS

In an experimental setup, comprising an articulator, a pair of metal casts, and an optoelectronic measurement system, the spatial position of the incisal point and two condylar points were measured. To evaluate the accuracy of repeated repositioning of casts in the technical workflow, 324 measurements were taken from 108 recordings, consisting of silicone bite-stops made of addition curing silicone with 95 shore hardness, acrylic wafers, and wax recordings. The recordings were obtained in four jaw relations differing in vertical and protrusive components.

RESULTS

Of the three materials/material combinations examined, silicone showed the most consistent results across all measurements, followed by the acrylic wafer system, and then wax recordings. Generally, recordings with smaller gaps between the jaws and no protrusive components showed greater deviations compared to jaw positions with greater protrusion and higher vertical dimensions.

CONCLUSIONS AND CLINICAL RELEVANCE

To achieve reliable model mounting with high accuracy, recordings should include the use of a frontal jig and four small recording platelets made of silicone, especially if only a slight elevation of the vertical dimension is needed.

Persisting effects of jaw clenching on dynamic steady-state balance

The effects of jaw clenching on balance has been shown under static steady-state conditions but the effects on dynamic steady-state balance have not yet been investigated. On this basis, the research questions were: 1) if jaw clenching improves dynamic steady-state balance; 2) if the effects persist when the jaw clenching task loses its novelty and the increased attention associated with it; 3) if the improved dynamic steady-state balance performance is associated with decreased muscle activity. A total of 48 physically active healthy adults were assigned to three groups differing in intervention (Jaw clenching and balance training (JBT), only balance training (OBT) or the no-training control group (CON)) and attending two measurement points separated by two weeks. A stabilometer was used to assess the dynamic steady-state balance performance in a jaw clenching and non-clenching condition. Dynamic steady-state balance performance was measured by the time at equilibrium (TAE). The activities of tibialis anterior (TA), gastrocnemius medialis (GM), rectus femoris (RF), biceps femoris (BF) and masseter (MA) muscles were recorded by a wireless EMG system. Integrated EMG (iEMG) was calculated to quantify the muscle activities. All groups had better dynamic steady-state balance performance in the jaw clenching condition than non-clenching at T1, and the positive effects persisted at T2 even though the jaw clenching task lost its novelty and attention associated with it after balance training with simultaneous jaw clenching. Independent of the intervention, all groups had better dynamic steady-state balance performances at T2. Moreover, reductions in muscle activities were observed at T2 parallel to the dynamic steady-state balance performance improvement. Previous studies showed that jaw clenching alters balance during upright standing, predictable perturbations when standing on the ground and unpredictable perturbations when standing on an oscillating platform. This study complemented the previous findings by showing positive effects of jaw clenching on dynamic steady-state balance performance.

Modular training model for education of students in restorative and prosthodontic dentistry

INTRODUCTION

At the moment, no commercial model solution is available for the individualisation of the dentition depending on the clinical case scenario. Furthermore, the realistic training of most restorative and prosthodontic procedures on a single dental study model is not possible. The aim of this study was the creation of a new training model to fill this gap.

MATERIALS AND METHODS

Complete upper and lower jaw models were created based on existing scans and radiological data from a patient. All components for 100 complete models and 1128 teeth for the training were produced with a SLA-printer. Overall, 94 voluntary students attending the first and second preclinical course in prosthodontics tested the functionality of the model with three different tooth types against a standard dental study model and real teeth. After the training, the model was rated in a questionnaire.

RESULTS

The production of the models and teeth was feasible. The overall rating of the different teeth was worse for type I (Ø 3.6 ± 1.1), significantly better for type II (Ø 2.5 ± 1.0) and type III (Ø 2.4 ± 1.0) than a standard typodont tooth (Ø 2.7 ± 1.1). The new model was rated significantly better overall (Ø 2.6 ± 1.0) than the standard training model (Ø 3.0 ± 1.1).

CONCLUSIONS

The aim of this study was fulfilled. A superior training model was created with equivalent and better tooth types. The new teeth were outstanding in terms of cost-efficiency, appearance and feeling during preparation.

Impact of dental prosthetic treatment and patients' expectations on the seven domains and four-dimensional scale of the Oral Health Impact Profile

BACKGROUND

Recently, recommendations were given for a new scoring of the Oral Health Impact Profile (OHIP). The original seven domain structure should be replaced by a four-dimensional scale.

OBJECTIVES

To investigate the effect of dental prosthetic treatment on the seven domains and the four-dimensional scale of the OHIP-G49/53 questionnaire.

METHODS

Seventy four patients were grouped according their pre- and post-treatment situation and the type of treatment they received. Patients completed the OHIP-G49/53 questionnaire before prosthetic treatment (T0), and at 1 week (T1), 3 months (T2) and 6 months (T3) after treatment. Treatment effects on the seven domains and the four dimensions of the OHIP scale were analysed, and the oral health-related quality of life (OHRQoL) was measured. Patients' expectations of their prosthetic treatment were also evaluated. Data were analysed using two-way Mixed ANOVA, regression analysis, and Cronbach's alpha test with a level of significance of α ≤ .017.

RESULTS

OHRQoL significantly improved following prosthetic treatment compared with baseline. The largest improvement was found between T0 and T1 evaluations (all p ≤ .001). Unlike the seven-domain scale, the four OHIP dimensions demonstrated further significant improvements across the T1/T2/T3 evaluations (all p ≤ .017). Different pre-treatment findings had different treatment effects on the four OHIP dimensions and seven OHIP domains. Patients' expectations were mainly fulfilled.

CONCLUSION

Compared with the seven-domain scale, the four dimensions showed significant follow-up changes, suggesting the four dimensions are suitable for evaluating treatment effects up to 6 months. Clinically meaningful effects of dental prosthetic treatment can be sensitively measured using the four-dimensional OHIP scale.

Comprehensive Geriatric Assessment and Quality of Life Aspects in Patients with Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma (HNSCC)

To define frailty in older cancer patients, the aim of this study was to assess the geriatric status and quality of life (QoL) aspects in patients suffering from recurrent/metastatic head and neck squamous cell carcinoma (r/m HNSCC) under palliative treatment. A comprehensive geriatric assessment (CGA) was performed on 21 r/m HNSCC patients at two defined assessments, and the QoL aspects and the impact of descriptive data were evaluated. The Kolmogorov-Smirnov test, Spearman's rho correlation, and two-way mixed ANOVA were used for statistical analysis. All patients were found to be "frail". Pain, fatigue, and the burden of illness were the highest-rated symptoms. Oral function and orofacial appearance were highly impaired. A significant impact of descriptive data on the CGA and QoL results was found (all p ≤ 0.05). Thus, the CGA results revealed high frailty, severe comorbidities, and high impairments in QoL aspects. The CGA and QoL results were negatively affected by the primary HNSCC treatment approach, the need for prosthetic treatment, and worse oral functional capacity. Therefore, frailty in r/m HNSCC patients seems to be multidimensional. The evaluation of the CGA and QoL aspects in r/m HNSCC patients can be recommended to detect special needs, organize aftercare, and improve the support for frail and vulnerable cancer patients to create a multidisciplinary treatment approach.

A Novel Approach to Differentiating Erosive and Reticular Lichen Planus Based on the Percentage of Dental Surfaces With Metal Restorations

Introduction Oral lichen planus (OLP) and oral lichenoid reaction (OLR) constitute clinical entities with strong but unclear etiologic relation to dental materials. The aim of this study was to evaluate a correlation between the clinical form of OLP/OLR and the number of dental metal restorations in the oral cavity thus utilizing an exposure to metal (EM) index.  Material and methods The study type is experimental, and the study design is characterized as semiquantitative research that belongs to the branch of experimental research. Twenty-nine patients were chosen based on clinical (either reticular or erosive clinical forms) and histologic findings suggestive of OLP/OLR. The files of patients were retrieved from the archives of the Department of Oral Medicine/Pathology, School of Dentistry, Aristotle University of Thessaloniki, Greece, during the period 2009-2019. The medical history of the patients did not include any disorder or medication associated with lichenoid lesions and the measurements took place concurrently with the establishment of the diagnosis, thus no treatment for the lichen planus had been administered prior to the measurements. Quantitative measurement of the percentage of dental surfaces restored through metal restorations and correlation with the clinical and histologic findings of OLP/OLR was evaluated. The EM index was evaluated on a scale of 1-3, which corresponds to the percentage of dental surfaces restored through metal restorations. The statistical analysis was performed with the Pearson chi-square test and the significance level was set at p≤0.05. Results The EM index was measured by dividing each tooth into five surfaces (occlusal, mesial, distal, buccal, lingual), subsequently multiplying the number of available teeth with the number 5 to calculate the total number of surfaces, and then counting the number of surfaces with metal restorations - both fillings and crowns (in case of metal-ceramic crowns, the respective dental surface is taken into account only in case of macroscopically exposed metal), dividing the number of surfaces with metal restorations with the total number of surfaces and multiply by 100 so that the results take the form of percentages (%) and finally classifying the percentages into three groups: 1: 0% metal restorations, 2: 1-25% metal restorations, 3: >26% metal restorations). The percentage in female patients ranged from 0% to 100%, whereas it ranged from 0% to 60% in male patients. According to the clinical form of the lichenoid lesion, the percentage ranged from 0% to 60% in reticular lichen planus cases and from 0% to 100% in erosive lichen planus cases. There was no statistical difference between lichen planus cases, in total, and in normal oral epithelium. However, the levels of EM were marginally similar between the reticular lichen planus and the erosive lichen planus (Fisher's exact test, p = 0.056). Therefore, it may be the case that the EM index is higher in erosive lichenoid lesions. Conclusion In our study, the EM index was higher in female patients and in erosive lichenoid lesions. These findings should be tested and supported by larger samples of patients since the aforementioned Fisher's Exact Test, p = 0.056 could fall below the threshold of 0.05 if more patients were included. This is the first attempt to establish a novel approach to differentiating erosive and reticular lichen planus based on the percentage of dental surfaces with metal restorations.

Cancer Stem Cells' Biomarker ALDH1&2 Increased Expression in Erosive Oral Lichen Planus Compared to Oral Leukoplakia

INTRODUCTION

ALDH1&2 has been considered an oral cancer stem cell (CSC) marker. Oral carcinogenesis is a process that usually passes through oral potentially malignant disorders (OPMD). Oral lichen planus (OLP) consists of immune-related chronic disorders that have been included in the OPMDs due to their possible transformation into oral cancer. The aim of this study was to investigate the early presence of ALDH1&2 in OLP compared to early oral leukoplakias (OL), especially mildly and non-dysplastic OL.

MATERIALS AND METHODS

The study type is experimental, and the study design is characterized as semiquantitative research which belongs to the branch of experimental research. The study sample consisted of paraffin-embedded OLP biopsy samples from the archives of the Department of Oral Medicine/Pathology, School of Dentistry, Aristotle University of Thessaloniki, Greece, during the period 2009-2019. The study sample contained 24 cases of OLP (14 erosive and 10 reticular) and 30 cases of OL (16 cases of moderately and severely dysplastic OL and 14 cases of mildly and non-dysplastic OL). The CSC-related biomarker ALDH1&2 was examined using semiquantitative immunohistochemistry (monoclonal antibody sc-166362, Santa Cruz Biotechnology, Dallas, Texas, USA, 1:100). ALDH1&2 expression was evaluated through a scale of 1 to 3 depending on the percentage of positive epithelial cells and was compared to normal epithelium as well as cases of OL (the most prominent OPMD). The statistical analysis was performed with the Pearson chi-square test and the significance level was set at p≤0.05.

RESULTS

The cytoplasmic staining of ALDH1&2 was observed mostly in the epithelial cells of the basal layer of the epithelium of OLP. Overall, this expression was significantly increased compared to normal epithelium. In addition, statistically significantly higher expression of ALDH1&2 was observed in the erosive form of OLP. Interestingly, this OLP positivity was higher compared to mild and non-dysplastic leukoplakias (p<0.001).

CONCLUSIONS

ALDH1&2 is a confirmed CSC marker that was found to be clearly increased in OLP and characteristically in erosive OLP epithelium for the first time. Noteworthy, it was more prominent in erosive OLP rather than in mildly and non-dysplastic OL. Whether this pattern of expression raises the red flag of an early epithelial "CSC" phenotype in OLP or that ALDH1&2 expression indicates a response to the OLP inflammatory process requires further investigation.

Ceramic Crowns and Sleep Bruxism: First Results from a Randomized Trial

Background: This randomized clinical trial was conducted to assess whether sleep bruxism (SB) is associated with an increased rate of technical complications (ceramic defects) in lithium disilicate (LiDi) or zirconia (Z) molar single crowns (SCs). Methods: Adult patients were classified as affected or unaffected by SB based on structured questionnaires, clinical signs, and overnight portable electromyography (BruxOff) and block randomized into four groups according to SB status and crown material (LiDi or Z): LiDi-SB (n = 29), LiDi-no SB (n = 24), Z-SB (n = 23), and Z-no SB (n = 27). Differences in technical complications (main outcome) and survival and success rates (secondary outcomes) one year after crown cementation were assessed using Fisher’s exact test with significance level α = 0.05. Results: No technical complications occurred. Restoration survival rates were 100% in the LiDi-SB and LiDi-no SB groups, 95.7% in the Z-SB group, and 96.3% in the Z-no SB group (p > 0.999). Success rates were 96.6% in the LiDi-SB group, 95.8% in the LiDi-no SB group (p > 0.999), 91.3% in the Z-SB group, and 96.3% in the Z-no SB group (p ≥ 0.588). Conclusions: With a limited observation time and sample size, no effect of SB on technical complication, survival, and success rates of molar LiDi and Z SCs was detected.

Photoacoustic tomography versus cone-beam computed tomography versus micro-computed tomography: Accuracy of 3D reconstructions of human teeth

OBJECTIVES

In this in-vitro study, teeth were imaged using photoacoustic tomography (PAT), cone-beam computed tomography (CBCT), and micro-computed tomography (μ-CT). The study had aim: to identify the best wavelength for PAT images to determine the accuracy of the three imaging methods, and to determine whether PAT images of teeth can achieve acceptable reconstruction quality.

METHODS

Nineteen human mandibular single-rooted incisors were extracted from patients with trauma or periodontitis. To determine the best wavelength for acquiring photoacoustic images, all 19 teeth were scanned in vitro with PAT, using different laser wavelengths between 680 and 960 nm. The images were analyzed using image analysis software. To assess the accuracy of PAT and compare it with the accuracy of CBCT, each tooth was also scanned in vitro using CBCT and the reference standard technique of μ-CT. Subsequently, three different three-dimensional models, one for each imaging technique, were created for each tooth. Finally, the three different three-dimensional models acquired for the same tooth were matched and analyzed regarding volume and surface.

RESULTS

The highest quality tooth images were achieved using the 680 nm wavelength, which showed the best contrast ratio. The full geometry of the dental root (μ-CT compared with PAT) could be visualized with relative standard deviations of 0.12 mm for the surface and -7.33 mm3 for the volume (n = 19). The full geometry of the dental root (μ-CT compared with CBCT) could be visualized with relative standard deviations of 0.06 mm for the surface and -14.56 mm3 for the volume (n = 19). The difference between the PAT-μ-CT group and CBCT-μ-CT group regarding the total average of the root surface area was not significant (p>0.06).

CONCLUSION

Images, which were acquired using PAT at 680nm showed the best contrast ration, enabling the identification of dentin, cementum and the dental pulp. No significant differences were found between the PAT-μ-CT group and CBCT-μ-CT group regarding the total average of the RSA and the total volume. Thus, three-dimensional reconstructions based on in-vitro PAT are already of acceptable reconstruction quality.

Control of occlusal rehabilitation with 3D-printed crowns

AIM

With the development of new materials, 3D printing has had an immense impact on dentistry. The latest innovations are the direct manufacturing of temporary and permanent crown and bridge restorations, inlays, onlays, and veneers. In the present case report, 3D-printing technology was used to control and adjust the occlusal rehabilitation with 3D-printed crowns.

MATERIALS AND METHODS

A 44-year-old male patient with pathologic dental attrition visited the Department of Restorative Dentistry at the University of Würzburg (Würzburg, Germany). The attrition process was far advanced, and no conventional conservative therapy was indicated. For the rehabilitation of the tooth substance loss, dental height, and appearance, a permanent solution with dental crowns was elected. After the preparation, the restorations were constructed digitally. For the control of the occlusal height, appearance, and color, the restorations were fabricated with a 3D printer and temporarily cemented. The crowns showed a high precision, and only minimal occlusal corrections were needed. After a trial period of 2 weeks and another fine occlusal adjustment, the temporary crowns were removed and scanned. The data were matched to the original construction file, which could be used to optimize the final rehabilitation. The final restorations were made of monolithic zirconia, with only minimal occlusal corrections required.

CONCLUSION

At the present time, dentistry is experiencing a great shift toward new and interesting production solutions with 3D-printing technologies. Such technologies give dentists the ability to create more predictable and cost-effective treatments. 3D printing is already being used to create temporary and definitive dental crowns as well as complex treatments, as is shown in the present case report. (Int J Comput Dent 2022;25(3):325-332; doi: 10.3290/j.ijcd.b3380909).

Oral-Health-Related Quality of Life in Patients with Medication-Related Osteonecrosis of the Jaw: A Prospective Clinical Study

Medication-related osteonecrosis of the jaw (MRONJ) represents an adverse side effect of antiresorptive and antiangiogenic medications. It is associated with impaired quality of life, oral health, and oral function and can be classified into various stages. The purpose of this prospective clinical study is to evaluate the impact of stages I and II MRONJ on oral-health-related quality of life (OHRQoL) and related parameters. Patients' OHRQoL, satisfaction with life, oral discomfort, and oral health were assessed using the German version of the Oral Health Impact Profile (OHIP-G49), visual analog scales (VAS), and Satisfaction with Life Scale (SWLS) at baseline (T0), 10 days (T1), and 3 months after treatment (T2) in 36 patients. Data were analyzed using Kolmogorov-Smirnov test, two-way mixed ANOVAs, and follow-up Mann-Whitney U tests. The impact of treatment effects on the original seven OHIP domain structures and the recently introduced four-dimensional OHIP structure were evaluated using linear regression analysis. Thirty-six patients received surgical MRONJ treatment. Before treatment, patients' perceived OHRQoL, oral discomfort, oral health, and satisfaction with life were negatively affected by MRONJ. Surgical treatment significantly improved OHRQoL and related parameters (all p ≤ 0.012). This improvement was greater in patients with higher impairment at T0. OHRQoL and oral restrictions were still impaired after treatment in patients who needed prosthetic treatment. The four-dimensional structure revealed valuable information beyond the standard seven OHIP domains. Increased awareness of MRONJ risks and an interdisciplinary treatment approach for MRONJ patients are needed.

Variability of sleep bruxism-findings from consecutive nights of monitoring

OBJECTIVES

To determine sleep bruxism (SB) behavior during five consecutive nights and to identify correlations between SB episodes per hour (SB index) and sleep-time masseter-muscle activity (sMMA).

MATERIAL AND METHODS

Thirty-one participants were included in the study. Of these, 10 were classified as sleep bruxers (group SB-1) and nine as non-sleep bruxers (group non-SB). The bruxism status of these 19 patients was identified by means of questionnaires, an assessment of clinical symptoms, and electromyographic/electrocardiographic data (Bruxoff® device). The remaining 12 participants were also identified as bruxers, but based exclusively on data from the Bruxoff device (group SB-2). Data analysis included descriptive statistics and Spearman's correlation to assess the relationship between the SB index and sMMA.

RESULTS

Participants in group SB-1 showed an overall mean SB index of 3.1 ± 1.6 and a mean total sMMA per night of 62.9 ± 38.3. Participants in group SB-2 had an overall mean SB index of 2.7 ± 1.5 and a mean total sMMA of 56.0 ± 29.3. In the non-SB group, participants showed an overall mean SB index of 0.8 ± 0.5 and a mean total sMMA of 56.8 ± 30.3. Spearman's correlation yielded values of - 0.27 to 0.71 for the correlation between sMMA and SB index.

CONCLUSIONS

The data revealed variable SB activity and the absence of a reliable correlation between sMMA and the SB index.

CLINICAL RELEVANCE

The high variation in SB activity and lack of correlation between sMMA and the SB index should be considered when diagnosing SB.

TRIAL REGISTRATION

Clinical Trials [NIH], clinical trial no. NCT03039985.

The "Painting by Numbers Method" for education of students in crown preparation

INTRODUCTION

No commercially available solution to improve the teaching of a crown preparation directly on typodont teeth exists at the moment. To fill this gap and support the supervisors of dental courses, a printable and inexpensive tooth was created for structured self-assessment. The aim of this study was to test this printable tooth under realistic pre-clinical situations.

MATERIALS AND METHODS

A two-coloured, double-layer practice tooth was developed. This tooth was consisting of a layer for a correct preparation and the crown. All printed teeth were produced with a stereolithographic printer. 35 voluntary second-year dental students in the second pre-clinical course in prosthodontics were randomly divided into two groups. All students had experience with typodont teeth and models. The first group was trained on four standard model teeth. The second group used model teeth for the first and fourth attempt and printed teeth for second and third attempt. The preparations of the students were scanned by an in-lab scanner and the surface deviations in contrast to a perfect preparation were measured. The differences between the first and fourth attempt were calculated. Benefits of the printed tooth were also evaluated by a questionnaire using German school grades completed by the students (1 = Excellent, 2 = Good, 3 = Satisfactory, 4 = Adequate, 5 = Poor, 6 = Unsatisfactory).

RESULTS

The workflow was feasible and cost-effective regarding the production of the printed teeth. The overall rating of the printed tooth in the questionnaire was good (Ø 2.1 ± 0.22). Students reported different advantages of this method in the free text. The comparison of the preparation between the first and fourth attempt showed that there was a significant better preparation with the printed teeth. The complete preparation had median values of 0.05 mm (Group1: standard model tooth) and -0.03 mm (Group2: printed tooth) (P = .005). Divided into single surfaces, the vestibular and occlusal regions were significantly better. The vestibular surface was 0.11 mm (Group1) and -0.04 mm (Group2) (P = .018). The occlusal surface was 0.13 mm (Group1) and -0.05 mm (Group2) (P = .009).

CONCLUSIONS

The aim of this study was fulfilled. The printed tooth was tested successfully in a pre-clinical course. The feasibility of this teaching concept was confirmed by the questionnaire and the analysis of the preparation form. A significant difference to a standard model tooth was measurable. The students had the possibility to learn a correct crown preparation on a standardised two-layered tooth with included preparation. This printed tooth enabled the students to control the crown preparation directly on their own.

Impact of Missing Teeth on Oral-Health-Related Quality of Life: A Prospective Bicenter Clinical Trial

PURPOSE

To investigate the effect of missing teeth on patients' oral health-related quality of life (OHRQoL).

MATERIALS AND METHODS

A total of 151 patients participated in this prospective bicenter clinical study (mean age: 64.7 ± 10.5 years; 71 women). Four subgroups were defined based on the number of missing teeth. OHRQoL was assessed using the German version of the Oral Health Impact Profile-49/53 (OHIP-G49/53) and visual analog scale (VAS) questionnaires. The effect of missing teeth on OHIP (total and by dimension) and VAS scores before and after prosthetic treatment was investigated at baseline (T0), 1 week (T1), and 3 months (T2) after prosthetic treatment. Scores were analyzed using Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests. Correlations were assessed using Spearman rho correlation. The level of significance was set at P = .05.

RESULTS

Initial OHIP and VAS scores were highest for patients with 11 to 28 missing teeth. Scores improved among all groups between T0 and T1/T2. After prosthetic rehabilitation (T1), improvements in total OHIP scores were greatest for patients with no missing teeth or with 11 to 28 missing teeth. Patients with no missing teeth or with 1 to 4 missing teeth before treatment had the lowest posttreatment OHIP scores. Total OHIP scores among the groups were in the same value range (P > .185). No direct correlation was found between the VAS and total OHIP scores.

CONCLUSION

OHIP and VAS scores for OHRQoL were associated with the number of missing teeth. Prosthetic treatment resulted in improved OHRQoL and oral function among all groups. The use of a VAS yielded additional detailed information.

Influence of dental tissue substructure and dimension on the fracture strength of lithium disilicate and zirconia ceramics

PURPOSE

To assess the influence of substructure and dimension on the fracture strength of ceramic discs made from both lithium disilicate ceramic and zirconia.

MATERIALS AND METHODS

A total of 128 intact maxillary third molars were collected, and standardized enamel and dentin discs were fabricated. Lithium disilicate ceramic (IPS e.max CAD, Ivoclar Vivadent; n = 64) and zirconia (Katana, Kuraray; n = 64) discs with 0.5-mm (n = 32 IPS and n = 32 Katana) and 1-mm (n = 32 IPS and n = 32 Katana) thickness were produced, and each group was divided into two subgroups (n = 16 each) that were luted to the enamel or dentin discs using Panavia V5 (Kuraray). Half of the specimens in each subgroup were aged (chewing simulation and thermocycling), and all specimens were loaded until fracture in a universal testing machine (Z010, Zwick/Roell). Differences between Katana and IPS with respect to enamel and dentin as substructure and the thickness of the ceramic were analyzed by use of a nonparametric test (Mann-Whitney U test).

RESULTS

In un-aged specimens, fracture loads were not significantly (P > .05) different between zirconia and IPS specimens for 1- or 0.5-mm thickness. However, fracture loads were significantly higher (P < .001) in specimens supported by enamel, independent of the ceramic material. In aged specimens, the fracture loads of all specimens were significantly (P < .01) higher when supported by enamel; however, in the 0.5-mm groups, zirconia achieved significantly higher breaking loads than IPS when luted to dentin.

CONCLUSION

When 0.5-mm ceramic discs were luted to dentin, zirconia outperformed IPS with respect to breaking loads.

Impact of different types of dental prostheses on oral-health-related quality of life: a prospective bicenter study of definitive and interim restorations

PURPOSE

To assess the impact of different types of dental prostheses, including definitive and interim restorations, on oral health-related quality of life (OHRQoL) before and after prosthetic treatment.

MATERIALS AND METHODS

A total of 151 patients received prosthetic treatment at one of two German departments of prosthetic dentistry. The patients' OHRQoL was assessed using the German version of the Oral Health Impact Profile (OHIP-G53) at baseline (T0) and at 1 week (T1) and 3 months (T2) after treatment. Patients were divided into 10 subgroups according to their pre- and posttreatment status. The effect of the type (no prosthesis; fixed prosthesis; removable prosthesis) and duration of wear (definitive; interim) of the restorations was evaluated. Results were analyzed using Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests with a significance level of P = .05.

RESULTS

The highest OHRQoL was recorded for patients with fixed restorations, as indicated by the fact that their OHIP scores were lowest. A significant improvement in OHRQoL (P ≤ .034) was observed for patients who needed prostheses and were then treated with removable or fixed restorations. The OHIP score was affected by a change in restoration type. Rehabilitation with definitive prostheses had a significant effect on posttreatment OHRQoL (P ≤ .006).

CONCLUSION

In general, prosthetic rehabilitation by use of fixed or removable prostheses resulted in an improvement in OHRQoL. The use of the same type of restoration before and after treatment had a positive effect on OHRQoL. If possible, a change of restoration type should be avoided. For patients who require permanent prostheses, the use of fixed and removable restorations is recommended. For oral rehabilitation, fixed restorations should be preferred in order to achieve best possible improvement of OHIP score.

In vitro investigations on retention force behavior of conventional and modern double crown systems

OBJECTIVE

This study aimed to investigate the effects of long-term use on the retention force and wear behavior of double crown systems.

METHODS

Based on a common double crown design sixty pairs of telescopic crowns were fabricated and divided into six groups, each consisting ten samples: "Gold standard" cast gold alloy primary and secondary crown (GG) and cast non-precious alloy (NN), computer-aided design (CAD)/computer-aided manufacturing (CAM)-milled zirconia primary crown and galvanoformed secondary crown (ZG), CAD/CAM-milled non-precious alloy primary and secondary crown (CC NN), CAD/CAM-milled zirconia primary crown and non-precious alloy secondary crown (CC ZN) and CAD/CAM-milled zirconia primary crown and polyetheretherketone (PEEK) secondary crown (CC ZP). In the constant presence of artificial saliva, all samples were subjected to 10,000 joining-separation cycles at a velocity of 120 mm/min. Wear was analyzed by reflected light microscopy and confocal microscopy before and after artificial aging.

RESULTS

Retention force losses were observed in each group after long-term use, with significant losses in the groups ZG and CC ZP (p_ZG = 0.01, p_{CC ZP} = 0.049). During artificial aging, no significant differences in pull-off force were recorded for groups GG, NN and CC ZN. Regarding wear, merely the Y-TZP primary crowns of the CC ZP group displayed no surface changes.

SIGNIFICANCE

All tested production methods and material combinations seem to be suitable for clinical practice. CAD/CAM technology allows similarly predictable results to be achieved as the gold standard. Confocal microscopy is recommended for surface examinations of double crowns.

Diagnostic accuracy of the Diagnostic Criteria for Temporomandibular Disorders for children aged 8-12 years

BACKGROUND AND OBJECTIVE

Objective of this study was to determine whether the diagnostic accuracy of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) is sufficient for use among schoolchildren aged 8-12 years.

METHODS

This prospective cohort study on diagnostic accuracy with calibrated examiners was conducted among 533 children of both sexes aged 8-12 years, with and without TMD symptoms, selected randomly from the Rhein-Neckar district. Self-reporting of non-dental facial pain was used as the reference standard, against which we calculated the following for the pain-related items of the DC/TMD (index test): sensitivity, specificity, positive and negative likelihood ratios, diagnostic odds ratio, accuracy and 95% Wilson Score confidence intervals. We also calculated the area under the receiver-operating characteristic (AUROC) curve displaying sensitivity and specificity.

RESULTS

Our final sample consisted of 282 children, half of whom reported having facial pain and 3.2% reported sounds from the temporomandibular joints (TMJs). Despite high specificity (90.78%; 95% confidence interval (CI): [84.86%; 94.53%]), sensitivity of the adapted DC/TMD for pain on maximum jaw opening was poor (37.59%; 95% CI: [30.02%; 45.81%]). For pain on palpation, more similar values were recorded for sensitivity (74.47%; 95% CI: [66.69%; 80.95%]) and specificity (70.21%; 95% CI: [62.21%; 77.14%]). The diagnostic odds ratio was >1 for both examinations. The AUROC for pain on opening was 68.39% (95% CI: [62.62%; 74.16%]), and for pain on palpation, it was 74.63% (95% CI: [69.45%; 79.81%]), whereas the combination of both resulted to an AUROC of 74.09% (95% CI: [68.96%; 79.21%]). It was not possible to measure the diagnostic accuracy of the DC/TMD regarding TMJ sounds or jaw-opening limitations, as they occurred too rarely in our sample.

CONCLUSION

In this study, the diagnostic accuracy of the DC/TMD for TMD-related pain in children was lower than that recorded for adults in previous studies.

3D Printed Teeth with Included Veneer Preparation Guide

PURPOSE

The purpose of this study was the design, feasibility, and evaluation of a 3D printed tooth model with internal preparation for dental education in veneer preparation.

MATERIAL AND METHODS

A tooth with two different colored layers for the crown and the preparation form was designed and printed by a stereolithographic printer. In a voluntary course, 40 third- to fifth-year dental students were trained with these printed teeth in the clinical course. They had the opportunity to prepare four 3D printed teeth with an integrated veneer preparation. During their studies, they used standardized model teeth. The students rated the advantage in a questionnaire according to German school grades (1 best to 6 worst). For reliability analysis, Cronbach's alpha was calculated. Significant differences between groups were calculated using the Mann-Whitney U-test.

RESULTS

The production of the teeth was feasible and cost-effective. The overall mean rating of the printed teeth in the questionnaire was 1.8 ± 0.18. The students rated the learning results with the printed tooth as significantly better than the standard model tooth (mean 3.0 ± 0.86 vs. mean 2.1 ± 0.95; p < 0.001). The item "is a more suitable exercise option" in contrast to standard model teeth was evaluated with 1.9 ± 0.61. The item "the included preparation was clearly visible in color" was rated with 1.7 ± 0.71. "The tooth model illustrated visually an ideal preparation" was rated with 1.8 ± 0.65. Additionally, the students were interested in including more printed teeth into their studies (1.7 ± 0.86). In the open questions the students reported great benefits of this method.

CONCLUSIONS

The feasibility of this teaching concept was confirmed. The students favored working on the innovative 3D-teeth with internal veneer preparation, emphasizing the usefulness of this technique in dental education. The tooth enabled the students to control their preparation permanently on their own.

Oral health-related impact profile of patients treated with fixed, removable, and telescopic dental prostheses in student courses-a prospective bicenter clinical trial

Objectives

To analyze the oral health-related impact profile in patients treated with three different types of dental prosthesis in student courses.

Materials and Methods

This prospective bicenter clinical trial was conducted with 151 patients being treated with fixed (n = 70), removable (n = 61), or telescopic dental prostheses (n = 20) in clinical student courses of two German universities from October 2018 to October 2019. All patients completed three standardized German versions of the Oral Health Impact Profile (OHIP-G49/53) before prosthetic treatment (T0), at control after 1 week (T1), and after 3 months (T2), divided into five dimensions: (a) appearance, (b) oral function, (c) psychosocial impact, (d) linguistic limitations, and (e) orofacial pain. Data were analyzed with Kolmogorov–Smirnov, Wilcoxon signed-rank, Kruskal–Wallis, Mann–Whitney, and Cronbach’s alpha tests.

Results

Within T0–T1 and T0–T2, greater improvements were determined for removable compared with fixed dental prostheses for the dimensions’ oral function (p ≤ 0.014), linguistic limitations (p ≤ 0.016), and appearance (p ≤ 0.003). No significant differences were found between fixed and telescopic dental prostheses (p ≥ 0.104) or between removable (partial dental prosthesis with clasps and complete dental prosthesis) and telescopic dental prostheses (p ≥ 0.100). Within T1–T2, a significant improvement in orofacial pain could be determined (p = 0.007).

Conclusions

Restorations presented an improvement in oral health-related quality of life. Removable dental prostheses showed better improvement than fixed ones in various dimensions.

Clinical relevance

Knowledge about the influence of oral health-related quality of life on the three different types of prosthesis used in student courses can be of decisive help in dental consultations.

Introduction of a new teaching concept for crown preparation with 3D printed teeth

INTRODUCTION

For both students and teachers, it is challenging to learn and teach a correct crown preparation. The purpose of this study was the design, feasibility and evaluation of a 3D printed tooth model with internal preparation for dental education in crown preparation and to analyse the quality of the prepared printed teeth in comparison with prepared standard model teeth.

MATERIALS AND METHODS

A printable tooth was designed and printed by a stereolithographic printer. 38 fourth-year dental students in the first clinical course in prosthodontics were trained in a voluntary course using printed teeth. Different aspects of the printed tooth were evaluated by a questionnaire using German school grades (1 best to 5 worst). The quality of the preparation with the printed teeth and standard training teeth was also rated in an evaluation form done by an expert group consisting of five experienced dentists.

RESULTS

The workflow was feasible and cost-effective for the production of the teeth. The overall rating of the printed tooth was Ø 2.0 ± 0.34 in the questionnaire completed by the students. The students rated the printed tooth model (Ø 2.1 ± 0.85) as significantly better than the standard model tooth (Ø 3.3 ± 0.77; P = .000). The students reported great benefits in the use of this model tooth, for example valuable replacement of a standard model and real teeth, direct control of material loss. The quality of the preparation was evaluated by the expert group as significantly better with an overall mean grade of Ø 2.6 ± 0.37 for the printed teeth compared to Ø 2.9 ± 0.42 for the standard model teeth (P = .000).

CONCLUSIONS

The feasibility of this teaching concept was confirmed. The students favoured to work on the innovative 3D-teeth with internal preparation, emphasising the usefulness of this technique in dental education. The expert group confirmed also the significant training effect of this tooth model in contrast to a standard model tooth.

Introduction of a new teaching concept for dentin post preparation with 3D printed teeth

INTRODUCTION

The preparation for dentin posts is difficult and hard to learn. There are currently no reproducible simulation models to train this clinical procedure. The purpose of this study was the design, feasibility and evaluation of a three-dimensional (3D) printed tooth model for the pre-clinical teaching of students.

MATERIALS AND METHODS

A printable tooth was designed and printed by a stereolithographic printer. A total of 48 fourth-year dental students in the first clinical course in prosthodontics were trained in a voluntary hands-on course on 4 similar printed teeth. The students used standard model teeth and real-teeth models during their education. They had experience in caries removement and root canal treatment on real patients. Root perforations were counted for every attempt. The different benefits of the 3D printed tooth were evaluated by a questionnaire using German school grades from 1 (best) to 6 (worst).

RESULTS

The overall rating of the printed tooth was Ø1.9 ± 0.3. The item "suitable exercise option" was rated Ø2.0 ± 0.8, and the teeth were "easy to use" Ø1.9 ± 0.9. The item "realistic approach to dentin post preparation" was rated Ø2.1 ± 0.8, and the teeth showed the "shortcomings at a root perforation" Ø1.5 ± 0.6. The students reported to have much more motivation and enthusiasm to improve their skills with the printed teeth Ø2.1 ± 0.9. They had a strong desire to include these teeth in their pre-clinical education before the first patient treatment Ø1.6 ± 0.8. The success rate of the dentin post preparation was significantly better for the second 25% (P = .047) and fourth 48% (P = .04) attempt.

CONCLUSIONS

The feasibility of this teaching concept was confirmed. The students had the possibility to learn a correct dentin post preparation on a printed tooth model. The learning effect with this tooth model was rated as good to very good by the questionnaire.

CAD/CAM supported production process of standardized enamel and dentin tooth discs with different thicknesses for in vitro material testing

OBJECTIVE

The production of similar specimens for material testing is very difficult and crucial. This has much influence on the results of an experiment. With CAD design and new printing technologies it is possible to create individual devices to produce specimens for different testing situations. In this study different devices were designed for the standardized production of tooth discs for testing with bonded materials.

METHODS

The different devices were designed using optimized CAD for 3D printing. After the design, the different parts of the devices were printed using a desktop SLA 3D printer with high precision. Three different tools were needed for the generation of a standardized disc. After the production, the different devices were tested on natural teeth.

RESULTS

It is possible to generate very precise tools for the creation of round tooth discs. 40 tooth discs divided into 4 groups with a thickness of 2.0 mm, 2.5 mm, 3.0 mm and 3.5 mm and a constant diameter of 5 mm were produced. For all groups the median of the diameter and thickness was under +/-0.05 mm and the lower and the upper quartile were all under +/-0.06 mm.

SIGNIFICANCE

With this new approach the creation of very precise and uniform tooth discs is possible. The whole process for the creation of the tooth discs was standardized.

Occlusal dysesthesia-A clinical guideline

Background

The diagnosis and management of patients suffering from occlusal dysesthesia (OD) remain a major challenge for dental practitioners and affected patients.

Objectives

To present the results of a literature‐based expert consensus intended to promote better understanding of OD and to facilitate the identification and management of affected patients.

Methods

In 2018, electronic literature searches were carried out in PubMed, Cochrane Library and Google Scholar as well as in the archives of relevant journals not listed in these databases. This approach was complemented by a careful assessment of the reference lists of the identified relevant papers. The articles were weighted by evidence level, followed by an evaluation of their contents and a discussion. The result represents an expert consensus.

Results

Based on the contents of the 77 articles identified in the search, the current knowledge about clinical characteristics, epidemiology, aetiology, diagnostic process, differential diagnosis and management of OD is summarised.

Conclusions

Occlusal dysesthesia exists independently of the occlusion. Instead, it is the result of maladaptive signal processing. The focus should be on patient education, counselling, defocusing, cognitive behavioural therapy, supportive drug therapy and certain non‐specific measures. Irreversible, specifically an exclusively dental treatment approach must be avoided.

Design und Qualitätskontrolle der zahnmedizinischen Untersuchung in der NAKO Gesundheitsstudie

Hintergrund

Karies und Parodontitis sind weltweit hoch prävalente Erkrankungen. Durch ihre Erfassung im Rahmen der NAKO Gesundheitsstudie können Assoziationen zwischen oralen und systemischen Erkrankungen untersucht werden.

Fragestellung

In einer ersten Qualitätsanalyse zur Halbzeit der NAKO-Basiserhebung wird die Plausibilität der zahnmedizinischen Ergebnisse überprüft. Es werden Maßnahmen zur Verbesserung der Datenqualität vorgeschlagen.

Material und Methoden

Ein zahnmedizinisches Interview, eine Speichelprobengewinnung und eine Befunderhebung wurden durchgeführt. Im Rahmen der Level-1-Untersuchung wurden Zahn- und Prothesenanzahl erfasst. In der Level-2-Untersuchung wurden detaillierte parodontologische, kariologische und funktionelle Befunde erhoben. Alle Untersuchungen wurden von geschultem nichtzahnmedizinischen Personal durchgeführt. Es wurden Plausibilitätsprüfungen durchgeführt sowie Verteilungen deskriptiv dargestellt.

Ergebnisse

In die Analysen gingen Daten von 57.967 Interviewteilnehmer*innen, 56.913 Level-1- und 6295 Level-2-Teilnehmer*innen ein. Der Anteil fehlender Werte lag für die einzelnen Parameter der Level-1- und Level-2-Untersuchungen zwischen 0,02 % und 3,9 %. Die Parameter zeigten eine plausible Verteilung; vereinzelt wurden unplausible Werte beobachtet, z. B. beim horizontalen und vertikalen Überbiss (Overjet und Overbite). Anhand der Intraklassenkorrelationskoeffizienten wurden für die einzelnen Parameter Unterschiede zwischen regionalen Clustern, den Studienzentren und verschiedenen Untersucher*innen nachgewiesen.

Diskussion

Die bisherigen Ergebnisse bestätigten die Umsetzbarkeit des Studienprotokolls durch nichtzahnmedizinisches Personal und die erfolgreiche Integration in das Untersuchungsprogramm der NAKO Gesundheitsstudie. Die Studienzentren benötigen eine intensive zahnmedizinische Betreuung für das Qualitätsmanagement.

Comparison of acupuncture on specific and non-specific points for the treatment of painful temporomandibular disorders: A randomised controlled trial

BACKGROUND AND OBJECTIVE

The aim of this single-centre, two-arm, parallel-group, double-blinded, randomised controlled trial was to investigate the disputed specific effectiveness of acupuncture by comparing acupuncture on specific and non-specific points among patients with non-chronic, painful TMDs.

METHODS

Following predefined eligibility criteria, 49 consecutive patients of both sexes were recruited to the study. All subjects were diagnosed with a non-chronic (Graded Chronic Pain Scale grade <3) painful TMD, as assessed using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Patients were randomly assigned to group A (acupuncture on specific points) or group B (acupuncture on non-specific points) after the initial examination (T0). Both acupuncture treatment sessions were conducted by a trained dentist once a week for four weeks. The examination was repeated five weeks (T5) after T0 by one calibrated examiner who was unaware of the study groups. Characteristic pain intensity (CPI) was evaluated as the main outcome criterion and compared between times and treatment groups by means of non-parametric tests (significance level set at P = .05). Secondary outcomes comprised the maximum corrected active mouth-opening without pain (MAO); patients' expectations regarding acupuncture treatment and pain development; depressivity; and oral health-related quality of life (OHRQoL).

RESULTS

A total of 41 patients (38 female) successfully completed the study (mean age: 40.17 ± 16.61). The two groups did not differ significantly at any time in terms of age and CPI. However, CPI was significantly (P < .05) lower at T5 than at T0 for both groups (29.66 and 30.35% lower in group A and group B, respectively). An increase in MAO was observed at T5 for both groups but was significant for group B only (P = .016). All patients had positive expectations of acupuncture therapy, and the two groups did not differ significantly at T5 with regard to the extent to which their expectations had been fulfilled by the treatment (P = .717). Comparison of T0 and T5 showed a statistically significant reduction of depressivity for group A (P = .0205), but no significant change for group B (P = .329). At T5, OHRQoL had improved significantly for both groups (group A, P = .018; group B, P < .001) compared with at T0.

CONCLUSIONS

Acupuncture on both specific and non-specific points reduces the non-dysfunctional pain of TMD patients. The effect of acupuncture on painful TMD cannot be attributed to the specific point selection.

The flexural strength of CAD/CAM polymer crowns and the effect of artificial ageing on the fracture resistance of CAD/CAM polymer and ceramic single crowns

OBJECTIVES

The purpose of this study was to investigate the fracture resistance, flexural strength and Weibull modulus of an innovative CAD/CAM polymer and to compare its fracture resistance with that of glass ceramics.

MATERIALS AND METHODS

A total of 32 (n = 16 IPS e.max CAD (LIDI); n = 16 LuxaCam Composite (LUXA)) first mandibular molar crowns were fabricated and cemented onto metal dies by use of luting composite. Half of the specimens were loaded until fracture without prior artificial ageing. The other half were subjected to thermal (5°/55 °C) and mechanical (1,200,000 cycles, 80 N) cycling before fracture loading. Scanning electron microscopy was used to analyse fracture behaviour. A three-point bending test of the flexural strength of LUXA was performed according to ISO 6872:2008. Data were analysed by means of the Kolmogorov-Smirnov test, Mann-Whitney U-test (p < 0.05) and Weibull statistical analysis.

RESULTS

Initial fracture resistance of LIDI was significantly higher than that of LUXA. However, the initial fracture resistance of LIDI decreased significantly after artificial ageing. After ageing, fracture resistance was 1050.29 ± 325.08 N for LUXA and 1250.09 ± 32.53 N for LIDI. Three-point bending test yielded a mean flexural strength value for LUXA of 145.28 ± 18.21 MPa and a Weibull modulus of m = 9.51.

CONCLUSIONS

Polymer-based material tested in this study had a lower fracture resistance than that of the glass-ceramic material. Fracture resistance and flexural strength of LuxaCam Composite are sufficient for use in the first molar region.

CLINICAL RELEVANCE

The mechanical properties of this innovative polymer-based material indicate it can be used in the first molar region as a suitable alternative to glass ceramics. Further clinical studies are required to confirm this. The study presents an innovative material as an alternative to glassceramic for the clinical use in dentistry. The materials investigated were differently affected by artificial aging. Clinical use for patients with bruxism may be considered.

Periodontal Health and Use of Oral Health Services: A Comparison of Germans and Two Migrant Groups

A cross-sectional study was performed with 251 individuals, consisting of 127 Germans, 68 migrants from Turkey, and 56 resettlers (migrants from the former Soviet Union with German ancestors) to compare periodontal health status, with a special focus on associations with lifestyle and anthropometric factors, and use of dental health services. Maximal pocket depth was used as a clinical surrogate marker for periodontitis. Other variables were obtained by questionnaires administered by a Turkish or Russian interpreter. The age- and sex-adjusted prevalence of periodontitis was significantly higher in Turks (odds ratio (OR) 2.84, 95% CI = 1.53–5.26) and slightly higher in resettlers (OR = 1.33, 95% CI = 0.71–2.49). These differences are partly explained by a differential distribution of known risk factors for periodontitis. A full model showed a higher prevalence of maximal pocket depth above 5 mm in Turks (OR = 1.97, 95% CI = 0.99–3.92). Use of oral health services was significantly lower in the two migrant groups. Individuals who reported regular visits to a dentist had significantly less periodontitis, independent of migrant status. A reasonable conclusion is that, since oral health causes major chronic diseases and has a major effect on total health system expenditures, public health efforts both generally and specifically focused on migrant groups are warranted.

3D Printed Teeth for the Preclinical Education of Dental Students

A need for more realistic tooth models for education has often been expressed by dental students. The aim of this study was to design and create 3D printed teeth with anatomical details for use in preclinical dental education. A tooth with realistic carious lesions and pulp cavity was designed, and this tooth was used in 2018 with 47 dental students for preclinical education in caries excavation, direct capping of the pulp, core build-up, and crown preparation. The students had the ability to identify the carious lesions by a simulated radiograph and by tactile sense of the consistency. The benefits of the 3D printed tooth were evaluated by a questionnaire. The printed tooth was evaluated by grades (1=excellent, 2=good, 3=satisfactory, 4=adequate, 5=poor). The students gave the tooth an overall mean grade of 1.9, with a grade of 2.0 for the haptic impression, 1.5 for the exercise, 1.9 for the examination, and 1.5 for high practical relevance in contrast to a standard model tooth. The new features of the printed tooth were given a mean grade of 2.0 for the radiograph, 2.3 for consistency of the caries, 2.0 for the tooth filling, and 1.7 for the pulp capping as realistic. The students had the possibility to generate a complete concept for prosthodontic tooth treatment on an artificial 3D printed tooth.

Postendodontic Restoration: Endodontic Post-and-Core or No Post At All?

PURPOSE

The objective of this systematic review was to assess the impact of endodontic post insertion on the clinical performance of endodontically treated teeth (ETT).

MATERIALS AND METHODS

A specific PICO question was developed and a Medline search was performed in January 2017 using relevant terms in order to identify studies comparing the success/survival of dental restorations using endodontic posts or no posts. Additionally, the electronic databases "Opengrey", "BBO", "LILAC" and "IBECS" were assessed and a hand search of cross references from original articles and reviews was performed. The methodological quality of the included studies was assessed independently by three referees using (1) the critical appraisal skills program (CASP) and (2) Cochrane checklist (version 5.1.0).

RESULTS

A total of 14 studies were included, among them 11 randomized controlled trials (RCT), two prospective clinical trials, and one retrospective clinical trial. The overall quality of the studies was good according to the CASP. However, the Cochrane rating showed that in seven studies, the risk of bias was high in > 40% of the items, indicating a relevant level of methodological flaws. Three studies showed a low risk of bias in > 80% of the items. The majority (10 out of 14) of the clinical studies included failed to show a positive effect of post placement. A post effect is possible when no cavity wall is present.

CONCLUSION

There is no unequivocal clinical evidence to support or reject the use of posts even for no-wall cavities, either for direct or indirect restorations.

"Ferrule Comes First. Post Is Second!" Fake News and Alternative Facts? A Systematic Review

INTRODUCTION

Both the role of an endodontic post and the ferrule effect have been discussed for decades. The clinical impact of endodontic posts compared with post-free restoration with or without ferrule support was not systematically reviewed so far. It was assumed that the effect of an endodontic post compared with a post-free restoration can be evaluated only when at the same time a ferrule or no-ferrule situation was clinically compared.

METHODS

The specific PICO question was as follows: Patient: adults with sufficient endodontic treatment needing a core or post; Intervention: post-endodontic treatment using posts with or without ferrule; Comparison: post-endodontic treatment without posts with or without ferrule; Outcomes: failure rates of post/core complexes with or without ferrule support. A Medline search was performed via PubMed in June 2017 using relevant electronic databases. Additionally, hand search was performed. Only prospective clinical studies in humans comparing the success/survival of teeth restored with or without posts over a minimum time of observation of 5 years were included.

RESULTS

In total, 7 randomized controlled trials and 1 prospective clinical trial met inclusion criteria. Cochrane rating showed high risk of bias in 5 studies. Two of 3 studies support the ferrule-effect concept. Seven of 8 show no post effect. Clinical evidence regarding the influence of tooth location on its survival is scarce.

CONCLUSION

Ferrule effect and maintaining cavity walls are the predominant factors with regard to tooth and restoration survival of endodontically treated teeth. Most studies do not confirm a positive effect of post placement.

Quantitative sensory response of the SCM muscle on sustained low level activation simulating co-contractions during bruxing

OBJECTIVE

Bruxism is discussed as an etiological factor in the pathogenesis of orofacial and cervical pain. As the sternocleidomastoid muscle (SCM) is co-activated during clenching, our aim was to investigate, whether the muscle loading leads to peripheral or central sensitizations.

DESIGN

In twenty-one healthy female volunteers, somatosensory profiles of the SCM were recorded according to the test battery of the German Research Network on Neuropathic Pain (DFNS) prior to and after an isometric muscle exercise. QST comprised thermal and mechanical stimuli. A submaximal activation of the SCM (15% MVC) was kept for 10min in sitting position. In separate test sessions one month apart, one sham and one verum experiment were conducted in randomized order. During the muscle loading, the parameters cold detection threshold (CDT), mechanical pain sensitivity (MPS) and pressure pain treshold (PPT) were tested and experimental pain recorded by visual analogoue scales (VAS). All test sessions were performed during the follicular phase of the menstrual cycle (day 5), to avoid effects on pain perception. Data were analyzed with Repeated Measures ANOVA (SPSS 22.0) RESULTS: No significant changes were found during or after (sham) loading except for stimulus-response-function (SR, P=0.01) and PPT (P=0.02) in the sham test. No effect was observed in the verum experiment (P=0.12 up to 1.0).

CONCLUSION

Prolonged low level contraction of the SCM does not evoke painful sensitization. In contrast, submaximal muscle activation seems to have a protective effect corresponding to a training effect preventing sensitization.

Fracture behavior of all-ceramic, implant-supported, and tooth-implant-supported fixed dental prostheses

OBJECTIVES

In vitro investigation of the effects of fixed dental prosthesis (FDP) support and loading conditions on the fracture behavior of all-ceramic, zirconia-based FDP veneered with computer-aided design/computer-aided manufacturing (CAD/CAM)-manufactured lithium disilicate ceramic.

MATERIALS AND METHODS

Based on a model for a 3-unit FDP in the molar region (tooth in region 15, implant in region 17), 16 identical zirconia frameworks were fabricated and veneered with milled lithium disilicate ceramic. Another 16 FDPs were manufactured similarly, using a model in which the tooth was replaced by an implant. The specimens underwent 10,000 thermal cycles between 6.5 and 60 °C and 1,200,000 chewing cycles with a force magnitude of 100 N. All were then subsequently loaded until fracture in a universal testing device. Half of the FDPs were subjected to centric and axial loading on the pontic, the others to eccentric and oblique loading on one cusp of the pontic.

RESULTS

No failures were observed after artificial aging. Fracture loads of tooth-implant-supported restorations were 1636 ± 158 and 1086 ± 156 N for axial and oblique loading, respectively; implant-supported FDPs fractured at 1789 ± 202 and 1200 ± 68 N, respectively. Differences were significant for load application (P < 0.001) and support type (P = 0.020). For the two types of load application, fracture mode differed substantially: complete fracture was observed for centric and axial loading whereas mixed cohesive/adhesive failure was observed for many FDPs loaded eccentrically and obliquely.

CONCLUSIONS

The high incidence of chipping of manually veneered implant-supported all-ceramics restorations might be reduced by use of CAD/CAM-manufactured lithium disilicate veneers.

CLINICAL RELEVANCE

FDPs veneered with lithium disilicate resist occlusal forces of 500 N, irrespective of load application and support type. The fracture resistance of implant-supported FDPs was, however, higher than that of combined tooth-implant-supported FDPs. Their clinical use seems to be justified.

High-resolution MR imaging for dental impressions: a feasibility study

OBJECTIVES

Magnetic resonance imaging is an emerging technology in dental medicine. While low-resolution MRI has especially provided means to examine the temporomandibular joint due to its anatomic inaccessibility, it was the goal of this study to assess whether high-resolution MRI is capable of delivering a dataset sufficiently precise enough to serve as digital impression of human teeth.

MATERIALS AND METHODS

An informed and consenting patient in need of dental restoration with fixed partial dentures was chosen as subject. Two prepared teeth were measured using MRI and the dataset subjected to mathematical processing before Fourier transformation. After reconstruction, a 3D file was generated which was fed into an existing industry standard CAD/CAM process.

RESULTS

A framework for a fixed dental prosthesis was digitally modeled and manufactured by laser-sintering. The fit in situ was found to be acceptable by current clinical standards, which allowed permanent placement of the fixed prosthesis.

CONCLUSIONS

Using a clinical whole-body MR scanner with the addition of custom add-on hardware, contrast enhancement, and data post-processing, resolution and signal-to-noise ratio were sufficiently achieved to allow fabrication of a dental restoration in an acquisition time comparable to the setting time of common dental impression materials. Furthermore, the measurement was well tolerated.

CLINICAL RELEVANCE

The herein described method can be regarded as proof of principle that MRI is a promising option for digital impressions when fixed partial dentures are required.

Comparison of three different options for immediate treatment of painful temporomandibular disorders: a randomized, controlled pilot trial

OBJECTIVE

The purpose of this study was to compare the short-term effectiveness of three different types of immediate, non-pharmacological intervention for alleviation of the painful symptoms of temporomandibular disorders (TMD).

MATERIAL AND METHODS

Thirty-six patients (mean age 41.6 ± 16.7 years, 25 females) diagnosed with non-dysfunctional painful TMD received counselling and subsequently were randomly allocated to three treatment groups: patients in Group A received prefabricated oral splints with water-filled elastic pads (Aqualizer(®)), those in Group B were provided with vacuum-formed co-polyester oral splints and those in Group C were given appointments to receive Michigan-type hard splints. Clinical examination was conducted, at baseline and after 2 weeks, by use of the RDC/TMD. Current pain intensity was determined by evaluation of graded chronic pain status (GCPS) on a numerical rating scale (NRS). Active maximum mouth opening without pain (AMMOP) was also measured. Paired sample t-tests and one-way analysis of variance with a significance level of p ≤ 0.05 were conducted.

RESULTS

After 2 weeks, overall mean current pain was reduced by 41.95% (p < 0.001). Current pain reduction was significant for Group B (66.6%, p < 0.001) but not for Groups A (37.88%, p = 0.56) and C (22.29%, p = 0.26). After 2 weeks, current pain level for Group B was significantly lower than that for Group C (p = 0.041). Overall, there was a statistically significant increase of AMMOP (p = 0.01).

CONCLUSION

All therapeutic options were pain-reducing. The results from this study suggest that cost-effective and time-effective intervention of counselling combined with use of a vacuum-formed splint is a favourable option for initial, short-term treatment of painful TMD.