Comprehensive Multidimensional Liquid Chromatography-Mass Spectrometry for the Characterization of Charge Variants of a Bispecific Antibody.

Identification and further characterization of antibody charge variants is a crucial step during biopharmaceutical drug development, particularly with regard to the increasing complexity of novel antibody formats. As a standard analytical approach, manual offline fractionation of charge variants by cation-exchange chromatography followed by comprehensive analytical testing is applied. These conventional workflows are time-consuming and labor-intensive and overall reach their limits in terms of chromatographic separation of enhanced structural heterogeneities raised from new antibody formats. For these reasons, we aimed to develop an alternative online characterization strategy for charge variant characterization of a therapeutic bispecific antibody by online mD-LC-MS at middle-up (2D-LC-MS) and bottom-up (4D-LC-MS) level. Using the implemented online mD-LC-MS approach, all medium- and even low-abundant product variants previously identified by offline fraction experiments and liquid chromatography mass spectrometry could be monitored. The herein reported automated online mD-LC-MS methodology therefore represents a complementary and in part alternative approach for analytical method validation including multiattribute monitoring (MAM) strategies by mass spectrometry, offering various benefits including increased throughput and reduced sample handling and combined protein information at intact protein and peptide level.

Detailed Analytical Characterization of a Bispecific IgG1 CrossMab Antibody of the Knob-into-Hole Format Applying Various Stress Conditions Revealed Pronounced Stability.

In recent years, a variety of new antibody formats have been developed. One of these formats allows the binding of one type of antibody to two different epitopes. This can for example be achieved by introduction of the "knob-into-hole" format and a combined CrossMab approach. Due to their complexity, these bispecific antibodies are expected to result in an enhanced variety of different degradation products. Reports on the stability of these molecules are still largely lacking. To address this, a panel of stress conditions, including elevated temperature, pH, oxidizing agents, and forced glycation via glucose incubation, to identify and functionally evaluate critical quality attributes in the complementary-determining and conserved regions of a bispecific antibody was applied in this study. The exertion of various stress conditions combined with an assessment by size exclusion chromatography, ion exchange chromatography, LC-MS/MS peptide mapping, and functional evaluation by cell-based assays was adequate to identify chemical modification sites and assess the stability and integrity, as well as the functionality of a bispecific antibody. Stress conditions induced size variants and post-translational modifications, such as isomerization, deamidation, and oxidation, albeit to a modest extent. Of note, all the observed stress conditions largely maintained functionality. In summary, this study revealed the pronounced stability of IgG1 "knob-into-hole" bispecific CrossMab antibodies compared to already marketed antibody products.

Implementation of in vitro glycoengineering of monoclonal antibodies into downstream processing of industrial production.

In vitro glycoengineering using exoenzymes for specific modification is recognized as appropriate method to tailor sugar moieties of glycan structures during the recombinant production of monoclonal antibodies (mAbs). This report describes enhanced in vitro glycoengineering approaches using ß1,4-galactosyltransferase and α2,6-sialyltransferase to improve the efficiency of galactosylation and sialylation with the aim to implement in vitro glycoengineering into common mAb purification processes. Feasibility studies tested the potential of different in vitro glycoengineering protocols (two-step vs. one-step) to facilitate the overall procedure. Scalability of the reactions was demonstrated for mAb amounts ranging from 1 mg to 1 g. Additionally, the reactions of ß1,4-galactosyltransferase and α2,6-sialyltransferase were shown to work on column during affinity chromatography using Protein A or KappaSelect, the latter providing more efficient galactosylation and sialylation of IgG1 and IgG4 mAbs. Performing in vitro glycoengineering on column enabled the use of cell culture harvest that yielded results comparable to those of purified bulk. Based thereon, an optimized two-step mixed mode approach was found most appropriate to integrate in vitro glycoengineering of the IgG1 mAb into the overall manufacturing process. Using harvest for on-column reaction of ß1,4-galactosyltransferase combined with in-solution reaction of α2,6-sialyltransferase, this approach yielded 100% biantennary galactosylation and 61% biantennary sialylation. Moreover, the enzymes applied in in vitro glycoengineering could be separated, recycled and reused in further reactions to improve economic efficiency. Overall, the study provides a toolbox for in vitro glycoengineering and presents an optimized easy-to-handle workflow to implement this method into the downstream processing of industrial mAb production.

Dental Students' Oral Health-Related Quality of Life and Temporomandibular Dysfunction-Self-Rating versus Clinical Assessment.

The aim of this study was to compare dental students' self-perception of oral health with the results of a clinical examination of the masticatory system. Seventy-four dental students (38 (51.4%) females and 36 (48.6%) males) completed the Oral Health Impact Profile questionnaire (OHIP-G-14) and underwent a clinical examination according to the Graz Dysfunction Index (GDI). Data were analyzed with descriptive and comparative statistics. Median OHIP-G-14 scores were 3 (IQR 0-6) in the total collective, 4 (1-11) in females, and 2 (0-4) in males (p = 0.072). A score of 0 was found in 29.7% of the sample. The results of the GDI were 50% "normal function", 43.2% "adaptation", 5.4% "compensation", and 1.4% "dysfunction". The comparison of OHIP-G-14 scores and DGI groups showed a significant difference (p = 0.031). Based on the questionnaire, less than one third of the sample indicated maximum oral health-related quality of life. In contrast, the GDI revealed "normal function" or "adaptation" in 93.2%. Dental students underappreciated their oral health condition. Health assessments should not be solely questionnaire-based, especially in health professionals (-to-be). To establish a valid diagnosis of the state of health, self-assessment must be complemented by an objective clinical examination, e.g., GDI.

Fast analysis of antibody-derived therapeutics by automated multidimensional liquid chromatography - Mass spectrometry.

Characterization of post-translational modifications (PTMs) of therapeutic antibodies is commonly performed by bottom-up approaches, involving sample preparation and peptide analysis by liquid chromatography-mass spectrometry (LC-MS). Conventional sample preparation requires extensive hands-on time and can increase the risk of inducing artificial modifications as many off-line steps - denaturation, disulfide-reduction, alkylation and tryptic digestion - are performed. In this study, we developed an on-line multidimensional (mD)-LC-MS bottom-up approach for fast sample preparation and analysis of (formulated) monoclonal antibodies and antibody-derived therapeutics. This approach allows on-column reduction, tryptic digestion and subsequent peptide analysis by RP-MS. Optimization of the 1D -and 2D flow and temperature improved the trapping of small polar peptides during on-line peptide mapping analysis. These adaptations increased the sequence coverage (95-98% versus 86-94% for off-line approaches) and allowed identification of various PTMs (i.e. deamidation of asparagine, methionine oxidation and lysine glycation) within a single analysis. This workflow enables a fast (<2 h) characterization of antibody heterogeneities within a single run and a low amount of protein (10 µg). Importantly, the new mD-LC-MS bottom-up method was able to detect the polar, fast-eluting peptides: Fc oxidation at Hc-Met-252 and the Fc N-glycosylation at Hc-Asn-297, which can be challenging using mD-LC-MS. Moreover, the method showed good comparability across the different measurements (RSD of retention time in the range of 0.2-1.8% for polar peptides). The LC system was controlled by only a standard commercial software package which makes implementation for fast characterization of quality attributes relatively easy.

Inter-laboratory study to evaluate the performance of automated online characterization of antibody charge variants by multi-dimensional LC-MS/MS.

An international study was conducted to evaluate the performance and reliability of an online multi-dimensional (mD)-LC-MS/MS approach for the characterization of antibody charge variants. The characterization of antibody charge variants is traditionally performed by time-consuming, offline isolation of charge variant fractions by ion exchange chromatography (IEC) that are subsequently subjected individually to LC-MS/MS peptide mapping. This newly developed mD-LC-MS/MS approach enables automated and rapid characterization of charge variants using much lower sample requirements. This online workflow includes sample reduction, digestion, peptide mapping, and subsequent mass spectrometric analysis within a single, fully-automated procedure. The benefits of using online mD-LC-MS/MS for variant characterization include fewer handling steps, a more than 10-fold reduction in required sample amount, reduced sample hold time as well as a shortening of the overall turnaround time from weeks to few days compared to standard offline procedures. In this site-to-site comparison study, we evaluated the online peptide mapping data collected from charge variants of trastuzumab (Herceptin®) across three international laboratories. The purpose of this study was to compare the overall performance of the online mD-LC-MS/MS approach for antibody charge variant characterization, with all participating sites employing different mD-LC-MS/MS setups (e.g., instrument vendors, modules, columns, CDS software). The high sequence coverage (95%-97%) obtained in each laboratory, enabled a reproducible generation of tryptic peptides and the comparison of values of the charge variants. Results obtained at all three participating sites were in good agreement, highlighting the reliability and performance of this approach, and correspond with data gained by the standard offline procedure. Overall, our results underscore of the benefit mD-LC-MS/MS technology for therapeutic antibody characterization, confirming its potential to become an important tool in the toolbox of protein characterization scientists.

Medical Diagnoses, Mode of Residence, and Dental Treatment Demand under General Anesthesia in Special Needs Adults in Innsbruck, Austria. A Retrospective Breakdown of Four and a Half Years.

Regarding oral/dental care and attendance, special needs individuals depend on their caregivers' commitment. The purpose of this retrospective data analysis of adults who received dental general anesthesia (DGA) in Innsbruck, Austria, was a breakdown of demographic parameters (including the mode of accommodation/care), medical diagnoses (comprising intellectual/physical disablement (IPD) or psychiatric (anxiety) disorders (PDs)), and dental therapy performed under DGA. The sample was composed of 233 consecutive adults who underwent DGA from January 2015 to June 2019. Data were analyzed with descriptive and comparative statistics. In total, 133 (57.1%) subjects were male and 100 (42.9%) female; 176 (75.5%) had IPD and 57 (24.5%) PDs; 168 (72.1%) were living at private and 65 (27.9%) at nursing homes. Median age (IQR) was 35.6 (25.7-47.2) years. In the total sample, 5 (2-9) teeth were restored and 2 (0.5-6.5) teeth were extracted. Individuals with PDs had more teeth restored (p = 0.01) and extracted (p < 0.001) than individuals with IPD. Private home residents had more teeth restored (p < 0.001) but less teeth extracted (p = 0.003) than nursing home residents. Special needs individuals' oral health backlog should be tackled in private and institutional care modalities alike.

Recent advances in LC-MS based characterization of protein-based bio-therapeutics - mastering analytical challenges posed by the increasing format complexity.

Alongside the success of protein-based bio-therapeutics over the last decades and facilitated by advances both in protein engineering and manufacturing, new product formats progressively enter into the biopharmaceutical industry's pipelines with major implications on the analytical methods used for their characterization. While conventional approaches have proved sufficient for standard (IgG-like) molecules, the increased complexity of novel formats requires proper adjustments of the employed methodologies, in particular with regard to separation-based techniques coupled to UV/FLD detection. After introducing the status quo for the characterization of biopharmaceuticals in quality control settings, this review provides a comprehensive portrayal of emerging LC-MS based technologies, which have already demonstrated their potential to complement the existing analytical toolbox. In this context, the benefits of native LC-MS and two-/multidimensional LC-MS applications to assess product attributes while preserving the higher-order structure are discussed based on challenges arising from the analysis of complex product formats.

Esthetic Evaluation of Maxillary Single-Tooth Zirconia Implants in the Esthetic Zone.

The purpose of this study was to evaluate ceramic dental implants using different esthetic scores. A total of 53 ceramic dental implants were evaluated using the Pink Esthetic Score (PES), White Esthetic Score (WES), and Peri-Implant and Crown Index (PICI). Prosthodontists, orthodontists, oral surgeons, and dentistry students independently performed assessments. The mean value of combined PES + WES was 17.4 points, and the PICI was 523.2 points. Orthodontists assessed a significantly lower result in both indices compared to all other assessor groups (P ≤ .05). Patient satisfaction was very high. The esthetic scores around ceramic implants were considerably higher than the suggested threshold of clinical acceptability.

CBCT and MRT imaging in patients clinically diagnosed with temporomandibular joint arthralgia.

OBJECTIVES: To compare cone beam computed tomography (CBCT) and magnetic resonance tomography (MRT) in patients with temporomandibular joint (TMJ) arthralgia in respect of the evaluation of bony structures, and to correlate joint space distances measured in CBCT with the morphology and the position of the disc visualized in MRT. MATERIALS & METHODS: 26 temporomandibular joints (TMJs) in 13 patients clinically diagnosed with TMJ arthralgia were examined by both CBCT and MRT. All images were evaluated by use of a form. The results were compared in regard of conformability of the diagnoses of osseous structures established by each imaging method. Anterior, superior and posterior joint space distances measured in CBCT-images were related to disc morphology and position visualized in MRT. RESULTS: Conformability of CBCT and MRT in the evaluation of bony TMJ structures ranged from 69.3 to 96.6 %. Osseous alterations such as erosions, osteophytes and cysts detected by CBCT could partly not be discerned by MRT. The correlation of joint space distances with disc morphology (biconcave or not biconcave) was not statistically significant. The correlation of joint space distances and disc position was statistically significant only for the superior joint distance. CONCLUSION: CBCT outclasses MRT in the visualization of osseous alterations, which are diacritic in the differentiation of simple arthralgia from osteoarthritis. Therefore, CBCT imaging is appropriate in patients clinically diagnosed with TMJ arthralgia.Superior joint space distance not being the highest joint space in sagittal CBCT indicates an anterior disc displacement.For the visualization of structural changes or displacement of the disc frequently associated with osseous changes, MRT is the optimal tool. Thus, the combination of the two imaging methods allows a comprehensive diagnosis in TMJ arthralgia patients.

In Vitro Analysis of the Fracture Resistance of CAD/CAM Denture Base Resins.

Computer-aided design and computer-aided manufacturing (CAD/CAM) denture base manufacturers claim to produce their resin pucks under high heat and pressure. Therefore, CAD/CAM dentures are assumed to have enhanced mechanical properties and, as a result, are often produced with lower denture base thicknesses than conventional, manually fabricated dentures. The aim of this study was to investigate if commercially available CAD/CAM denture base resins have more favourable mechanical properties than conventionally processed denture base resins. For this purpose, a series of three-point bending tests conforming to ISO specifications were performed on a total of 80 standardised, rectangular CAD/CAM denture base resin specimens from five different manufacturers (AvaDent, Baltic Denture System, Vita VIONIC, Whole You Nexteeth, and Wieland Digital Dentures). A heat-polymerising resin and an autopolymerising resin served as the control groups. The breaking load, fracture toughness, and the elastic modulus were assessed. Additionally, the fracture surface roughness and texture were investigated. Only one CAD/CAM resin showed a significantly increased breaking load. Two CAD/CAM resins had a significantly higher fracture toughness than the control groups, and all CAD/CAM resins had higher elastic moduli than the controls. Our results indicate that CAD/CAM denture base resins do not generally have better mechanical properties than manually processed resins. Therefore, the lower minimum denture base thicknesses should be regarded with some caution.

CAD/CAM produces dentures with improved fit.

OBJECTIVES: Resin polymerisation shrinkage reduces the congruence of the denture base with denture-bearing tissues and thereby decreases the retention of conventionally fabricated dentures. CAD/CAM denture manufacturing is a subtractive process, and polymerisation shrinkage is not an issue anymore. Therefore, CAD/CAM dentures are assumed to show a higher denture base congruence than conventionally fabricated dentures. It has been the aim of this study to test this hypothesis. MATERIALS AND METHODS: CAD/CAM dentures provided by four different manufacturers (AvaDent, Merz Dental, Whole You, Wieland/Ivoclar) were generated from ten different master casts. Ten conventional dentures (pack and press, long-term heat polymerisation) made from the same master casts served as control group. The master casts and all denture bases were scanned and matched digitally. The absolute incongruences were measured using a 2-mm mesh. RESULTS: Conventionally fabricated dentures showed a mean deviation of 0.105 mm, SD = 0.019 from the master cast. All CAD/CAM dentures showed lower mean incongruences. From all CAD/CAM dentures, AvaDent Digital Dentures showed the highest congruence with the master cast surface with a mean deviation of 0.058 mm, SD = 0.005. Wieland Digital Dentures showed a mean deviation of 0.068 mm, SD = 0.005, Whole You Nexteeth prostheses showed a mean deviation of 0.074 mm, SD = 0.011 and Baltic Denture System prostheses showed a mean deviation of 0.086 mm, SD = 0.012. CONCLUSIONS: CAD/CAM produces dentures with better fit than conventional dentures. CLINICAL RELEVANCE: The present study explains the clinically observed enhanced retention and lower traumatic ulcer-frequency in CAD/CAM dentures.

Evaluation of Currently Available CAD/CAM Denture Systems.

PURPOSE: The introduction of computer-aided design/computer-assisted manufacture (CAD/CAM) technology into removable denture prosthodontics enables denture adaptation in fewer patient visits, an advantage that appeals to dentists and patients. Since manufacturers follow very different approaches, an evaluation of the different clinical CAD/CAM complete denture fabrication protocols is desirable. The aim of this article is to assess and evaluate the different clinical fabrication protocols of currently available CAD/CAM denture systems to provide decision support for dental practitioners. MATERIALS AND METHODS: The information for the present article was gathered by questionnaires from (in alphabetical order) Global Dental Science, Merz Dental, Wieland Dental + Technik, Ivoclar Vivadent, VITA Zahnfabrik, and Whole You, and complemented with results from the authors' clinical experience. RESULTS: Wieland Digital Denture involves four patient visits. Both AvaDent digital dentures and Whole You Nexteeth enable denture fabrication in three (including a try-in session) or two (without try-in) visits. Baltic Denture System stipulates complete denture fabrication in two visits, and VITA VIONIC material system is an open system enabling choice between different treatment protocols. It can be combined with several open scanners, CAD software options, and milling machines. CONCLUSION: The available CAD/CAM denture fabrication systems provide a variety of advantages, and the decision on a system should depend on the dentist's prosthodontic expertise, patient throughput rate, and requirements regarding denture individualization.

Do CAD/CAM dentures really release less monomer than conventional dentures?

OBJECTIVES: Computer-aided design (CAD)/computer-aided manufacturing (CAM) dentures are assumed to have more favourable material properties than conventionally fabricated dentures, among them a lower methacrylate monomer release. The aim of this study was to test this hypothesis. MATERIALS AND METHODS: CAD/CAM dentures were generated from ten different master casts by using four different CAD/CAM systems. Conventional, heat-polymerised dentures served as control group. Denture weight and volume were measured; the density was calculated, and the denture surface area was assessed digitally. The monomer release after 7 days of water storage was measured by high-performance liquid chromatography. RESULTS: Whole You Nexteeth and Wieland Digital Dentures had significantly lower mean volume and weight than conventional dentures. Baltic Denture System and Whole You Nexteeth had a significantly increased density. Baltic Denture System had a significantly smaller surface area. None of the CAD/CAM dentures released significantly less monomer than the control group. CONCLUSIONS: All tested dentures released very low amounts of methacrylate monomer, but not significantly less than conventional dentures. A statistically significant difference might nevertheless exist in comparison to other, less recommendable denture base materials, such as the frequently used autopolymerising resins. CLINICAL RELEVANCE: CAD/CAM denture fabrication has numerous advantages. It enables the fabrication of dentures with lower resin volume and lower denture weight. Both could increase the patient comfort. Dentures with higher density might exhibit more favourable mechanical properties. The hypothesis that CAD/CAM dentures release less monomer than conventional dentures could, however, not be verified.

Is Cognitive Status Related to Oral Hygiene Level and Appropriate for Determining Need for Oral Hygiene Assistance?

BACKGROUND: With declining general health, the maintenance of oral health becomes increasingly difficult. Unfortunately, health care resources are limited. An assessment tool for detecting a patient's need for oral health care assistance would promote its adequate distribution. The aim of this study is to evaluate if the Shulman clock-drawing test score is a suitable assessment tool for determining the need for oral hygiene assistance. METHODS: Data collected from recent dental checkups of 126 inhabitants of five Austrian residential care facilities were analyzed. The Shulman clock-drawing test score was used as a measure for cognitive abilities and related to tooth and denture hygiene indices, which were assessed using the approximal space plaque index (API) and the denture plaque index (DPI). RESULTS: Shulman score values were distributed almost evenly in the study population. The mean API was 83.6% (SD 20.2%) for the maxilla and 94.9% (SD 15.6%) for the mandible. The mean DPI was 43.9% (SD 31.4%). Cognitive impairment was not statistically related to the dental or denture hygiene index. CONCLUSIONS: A high Shulman clock-drawing test score indicates the need for oral hygiene assistance, but it is not suitable as a single tool to assess this need. Patients with other disabilities might equally qualify for assistance. Dentures, however, can be cleaned quickly and efficiently independently of patient compliance; therefore, cleaning the patients' dentures should be part of nursing personnel's daily care routine for every patient.

A 7-year prospective radiographic evaluation of marginal bone level around two different implant systems: a randomized clinical trial.

OBJECTIVE: The aim of this study was to evaluate the change in marginal bone level radiographically around two different implant systems after 7 years of use. MATERIAL AND METHODS: Twenty fully edentulous patients were included in the study and randomly assigned to two treatment groups of machined surface implants (Brånemark, n = 40) and rough-surface implants (Xive, n = 40). The implants were early loaded with individual bar-retained overdentures. All patients were treated by the same surgeon and the same prosthodontist. Clinical and radiographic examinations were conducted at the time of implant loading (baseline) and annually for up to 7 years of use. Measurements to the nearest 0.1 mm were taken at the mesial and distal site, and the average values were calculated for each implant. A three-level mixed-effect analysis of covariance (ANOVA) was used to test the significance of the mean marginal bone change in the two implant groups. RESULTS: The study population consisted of 15 women (75%) and five men (25%) with an average age of 61.6 years. A total of 79 of 80 implants integrated successfully. n = 1 Brånemark implant failed after 3 weeks. There was a significant difference (P < 0.001) between the two implant systems at the baseline measurements (0.14 mm Brånemark vs. 0.39 mm Xive) and a highly significant difference for the annual bone loss (0.07 mm [Brånemark] vs. 0.18 mm [Xive], P < 0.001). CONCLUSION: Both the implant systems are clinically satisfying. Nevertheless, the Brånemark group showed a better radiological performance than the Xive group.

Dental zirconia implants up to three years in function: a retrospective clinical study and evaluation of prosthetic restorations and failures.

PURPOSE: The clinical evaluation of one-piece zirconia dental implants with different diameters to determine survival rate and type of implant failure. MATERIALS AND METHODS: Information concerning implant surgery (number, diameter, length, and position of inserted implants; patient age, sex, risk factors, and bone quality) was extracted from the clinical records. All treated patients were then recalled for a follow-up examination to check the current clinical parameters concerning soft tissue, implants, and prosthetic reconstructions. RESULTS: A total of 79 patients received 170 implants (diameter-reduced 3.25 mm: n = 59; diameter 4.0 mm: n = 82; diameter 5.0 mm: n = 29). The clinical examination showed no signs of gingival inflammation. Prosthetic information was available for 119 implants restored with single crowns (87 implants), fixed partial dentures (25 implants), and removable hybrid dentures (7 implants). Overall, 30 implants were lost due to lack of osseointegration (n = 17) or fracture (n = 13). The diameter-reduced implants showed the lowest survival rate (59.5%) compared to the implants with a diameter of 4.0 mm (90.6%) and 5.0 mm (73.9%). The survival rate for diameters of 3.25 mm was significantly lower than that for diameters of 4.0 mm. The estimated cumulative survival rate up to 3 years demonstrated a survival probability of 82.4% for all types of implant diameters and failure. CONCLUSIONS: Based on these results, diameter-reduced zirconia dental implants cannot be recommended for clinical use. The overall survival rate of 82.4% is not acceptable in comparison to the well-established survival rate of titanium implants.

Laboratory methods for evaluating the wear of denture teeth and their correlation with clinical results.

OBJECTIVE: To correlate different laboratory wear simulation protocols for three denture tooth materials with clinical wear results of the same materials. METHODS: Three denture tooth materials were evaluated for which clinical wear data of posterior denture teeth were available: DCL (double cross-linked PMMA with organic fillers; Ivoclar Vivadent), experimental material EM (double cross-linked PMMA with organic fillers; Ivoclar Vivadent), and NFC (PMMA with inorganic nanofillers, Candulor). The clinical data on the three denture tooth materials (10 subjects for each material) came from clinical studies conducted at three different locations. The investigators sent the impressions to one center where they were analyzed with the same methodology and by the same operator. Four different wear simulation protocols were evaluated in a chewing simulator (Willytec) with integrated thermocycling (5 °C/55 °C) and 8 specimens for each group: (A) molar denture tooth against premolar denture tooth with 1 mm sliding, lifting, 5 kg load; (B) standardized conical ceramic stylus (Ø2.3 mm); (C) standardized ball-shaped ceramic stylus (Ø6 mm); (D) standardized conical stylus (Ø2.3 mm) cut with a special bur from the denture tooth material to be tested. For the protocols B, C and D, the stylus slid under a load of 3 kg for 3 mm on the flat specimen without lifting. All the tests were run for 100,000 chewing cycles. The maximum vertical wear of the material and stylus was quantified on replicas of improved white stone with the etkon es1 scanner and the match 3-D software. RESULTS: The ranking of the materials according to mean clinical vertical wear after 1 year was as follows: DCL=EM>NFC. The ranking of the materials according to the mean vertical wear was as follows (ANOVA post hoc Tukey B, p<0.05): group A: NFC>DCL=EM; group B: NFC>DCL>EM; group C: NFC>DCL=EM; group D: DCL=EM>NFC. SIGNIFICANCE: Only the results of the experimental setup with standardized antagonists of the same denture tooth material against flat specimens were similar to the clinical wear results with a comparable relative difference in mean vertical wear between the materials. When evaluating denture teeth for wear in the laboratory, a protocol should be applied that matches the clinical wear results.

A 5-year prospective multicenter study on 1-stage smooth-surface Brånemark System implants with early loading in edentulous mandibles.

PURPOSE: The purpose of the current prospective multicenter study was to evaluate the 5-year implant success and peri-implant conditions of smooth-surface Brånemark System implants when using a novel technique including a 1-stage surgical procedure with early loading in edentulous mandibles. MATERIALS AND METHODS: The study protocol included 1-stage surgery as well as placement of the definitive prosthesis within 6 weeks after implant insertion (ie, early loading). Clinical evaluation, as well as evaluation of function and esthetics, was performed at each follow-up visit. Radiographs were obtained at connection of the prostheses and at the 1, 3-, and 5-year check-ups. RESULTS: A total of 40 patients with a mean age of 56 years (range, 30 to 70) were included in the study. In all, 170 implants were placed in between the mental foramina, of which 120 implants in 30 patients were associated with overdenture treatment and 50 implants in 10 patients with fixed complete dentures. Twelve implants failed in 6 patients. The cumulative implant survival rate was 92.9% after both 1 and 5 years of follow-up. Another 3 implants were recorded as mobile but still in function when individually checked at the 5-year visit, which resulted in a cumulative success rate of 91.0%. Mean bone remodeling over the study period was less than 0.1 mm/y after the first year of loading, resulting in a mean marginal bone level of 0.66 mm (SD 0.73, n = 138) apical to the implant collar reference point after 5 years. CONCLUSIONS: One-stage, early loaded smooth-surface Brånemark System implants functioned well for the majority of patients with edentulous mandibles. Stable peri-implant conditions were observed. Bone remodeling resulted in a mean bone level above the first implant thread after 5 years. The somewhat lower success rate of 91.0% compared to a 2-stage procedure may be related to generous inclusion criteria and to a learning curve involving a novel treatment procedure.

Correlations between AFM and SEM imaging of acid-etched tooth enamel.

Enamel bond strength is an important factor in restorative dentistry and crucially depends on the enamel roughness. To increase roughness, different etching procedures are employed and profilometric estimations, with probe profilometers, including atomic force microscopy (AFM), have been made. However, no correlation between roughness and bond strength has been found. To search for a possible error source leading to the underestimation of enamel roughness when utilizing probe profilometers, the authors compared scanning electron microscopy and AFM images of acid-etched tooth enamel. The results showed that AFM imaging cannot correctly depict the acid-etched enamel surface, because of the high steepness of the enamel crystallites and the generation of convolute images. This leads to a large underestimation of the profilometric parameters measured with AFM, or other profilometers, on acid-etched tooth enamel surfaces.