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.

The Power of Trypsin Immobilized Enzyme Reactors (IMERs) Deployed in Online MDLC–MS Applications

Immobilized enzyme reactors (IMERs) are a powerful and essential part of multidimensional liquid chromatography–tandem mass spectrometry (MDLC–MS/MS) approaches that enable online identification, characterization, and quantification of post-translational modifications of therapeutic antibodies. This review gives an overview of commercially available and selected trypsin IMERs in regard to their application in LC-based and automated sample preparation. Additionally, we address the challenges of IMER application in online systems and the advantages of self-made IMERs.

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.

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.

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 β1,4-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 (2-step vs. 1-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 β1,4-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 which yielded results comparable to that of purified bulk. Based thereon, an optimized 2-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 β1,4-galactosyltransferase combined with in-solution reaction of α2,6-sialyltransferase, this approach yielded 100 percent biantennary galactosylation and 61 percent 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.

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.

Is dental general anaesthesia in children an outdated concept? A retrospective analysis

AIM

The aim of this retrospective study was to determine the prevalence of caries and treatment needs in the collective of patients ?16 years of age, who underwent scheduled dental general anaesthesia (DGA) at the University Clinic of Innsbruck from January 2015 to June 2019, with respect to demographic factors.

MATERIALS AND METHODS

A retrospective analysis of children's diagnoses, demographics, and dental treatment under general anaesthesia in Innsbruck, Austria, from 2015 to 2019 was performed. Anonymised demographic data (age; gender; the presence or absence of general disease or disablement; parents' first language (German- (GS) or non-German-speaking (non-GS), reflecting ethnicity; and the number of teeth restored and extracted under DGA were collected from patients' files. Data was analysed by means of descriptive and comparative statistics.

RESULTS

The main group consisted of 545 subjects at a median age of 5.3 (IQR 4.4-6.6) years, who had exclusively primary teeth and or first molars that received restorations or were extracted. Of the subjects, 84.4% were classified with uncooperativeness due to dental anxiety and 15.6% with systemic diseases or intellectual and or physical disablement. In this group, 47.9% were GS and 52.1% were non-GS or had GS or non- GS parents. In the total sample, 5 (IQR 3-7) primary teeth were restored and 4 (IQR 4-7) extracted. Subgroup analysis revealed statistically significant differences in the number of extracted primary teeth between children with and without systemic diseases or disablement - 3 (IQR 1-5) versus 4 (IQR 2-7) - and between children of GS and non-GS parents - 4 (IQR 2-6) versus 5 (IQR 3-7.8). Zero (IQR 0-0) first molars were filled and extracted.

CONCLUSION

Within the study collective of children in poor oral health, the offspring of non-GS families were overrepresented (compared to their prevalence in the total population) and displayed a higher prevalence of deep caries than those of GS parents. By intensifying and special gearing of prophylactic measures to the non-GS population and promoting the parents' insight into the importance of oral hygiene and regular dental attendance, the demand for scheduled DGA might be greatly reduced. In the small share of children who suffer from severe diseases or disablement and are thus unable to cooperate with home care or dental treatment, DGA will remain the treatment of choice.

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.

Prosthetic rehabilitation of patients with hypohidrotic ectodermal dysplasia: A systematic review

Hypohidrotic ectodermal dysplasia (HED) comprises a large group of inherited disorders of ectodermal structures, characterised by hypo- or anhidrosis, hypotrichosis and hypo- or oligo- or anodontia. We aimed to systematically assess the spectrum of prosthodontic approaches with regard to the patients' age and to provide clinical implications for practicing dentists. An electronic and manual search was conducted in four databases (Medline, LIVIVO, Cochrane Library, Web of Science Core Collection). Publications of multiple study designs written in English or German without data restrictions, reporting on prosthodontic treatment of patients diagnosed with HED and afflicted with oligo- or anodontia, were included. In total, 75 articles on 146 patients were analysed according to the patients' age. In children aged 2-17 years, removable full or partial (over)dentures represented standard treatment. In the mandible, implant-supported removable dentures on two interforaminal implants presented an alternative, already in young childhood. In cases with more than six teeth per jaw, also fixed (resin) bridges were used, frequently after orthodontic treatment. In adults, fixed or removable reconstructions with the help of up to eight implants per jaw, usually placed after bone augmentation procedures, were standard. Ten case reports/series with long-term follow-up illustrated the need for consistent maintenance including denture renewals. Prosthodontic rehabilitation should start in early childhood and needs to be revised in accordance with the patients' growth. Treatment should be carried out by a multidisciplinary team addressing variable demands in different age groups.

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.

Shortcomings of prosthodontic rehabilitation of patients living in long-term care facilities

Removable dentures are a non-invasive, cost-effective prosthodontic solution for the reduced dentition. Their intended purpose is the rehabilitation of harmonious oral function and aesthetics on a long-term basis. The prevalence of removable dentures among patients of advanced age is high and the quality of the dentures is often poor. The aim of this study was to find the most important shortcomings of removable dentures and address the main targets for improving the quality of prosthodontic rehabilitation. The records from dental check-ups in Austrian residential homes were analysed retrospectively. Dental anamnesis questionnaires and data from the clinical examinations of 105 denture wearers were analysed. The functional condition and retention of 192 dentures had been assessed, as well as the impact of the dentures on the intra-oral tissues. Insufficient denture retention was very common, particularly in the lower jaw (56·0%). Problems with the masticatory function were reported by 26.7% of the denture wearers, 11·4% were dissatisfied with the denture aesthetics, and 4·8% had difficulties with phonetics. Traumatic ulcers were found in 18·1%. Cracks, broken pieces (6·3%) or missing denture teeth (2·1%) were rare. It may be assumed that the findings of the present study also apply to a great percentage of community-dwelling seniors. The most important issues in prosthodontic rehabilitation with removable dentures are denture retention and masticatory function. Regular dental check-ups, denture adjustment and, when necessary, relining can maintain the primary denture quality and prevent damages of the oral tissues caused by ill-fitting dentures.

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.

Quality of impressions using hydrophilic polyvinyl siloxane in a clinical study of 249 patients

PURPOSE

This study aimed to evaluate the clinical success of a hydrophilic polyvinyl siloxane impression material for fixed dental restorations under various clinical conditions.

MATERIALS AND METHODS

A total of 1,466 preparations for fixed restorations in maxillary and mandibular anterior and posterior teeth were evaluated. The study contained inlay, onlay, crown, veneer, post, and adhesive-wing preparations and implants for gold, porcelain-fused-to-metal, and ceramic restorations. The preparation finish line relative to the crest of the marginal gingiva, type of restoration, and position of the teeth were recorded. Three categories were established to rate impression quality: perfect impressions, with an absence of any voids or bubbles and perfect reproduction of the preparation finish line, were rated Criteria I; acceptable impressions, with minimal defects (< or = 2 mm) not involving the preparation finish line, were rated Criteria II; and unacceptable impressions, with larger voids or bubbles (> 2 mm) or defects involving the preparation finish line, were rated Criteria III.

RESULTS

Overall, 96.86% of the final impressions were clinically acceptable, 89.43% of which were rated Criteria I and 7.43% of which were rated Criteria II. Only 3.14% of the impressions were unacceptable and rated Criteria III. A significant influence on impression quality was found when the preparation finish line was more than 2 mm subgingival (P < .004), as well as when a beveled preparation was used (P < .004). The position of the teeth (P > .404) had no significant effect.

CONCLUSION

Surface-activated polyvinyl siloxane impression material offers high predictability to avoid bubbles and voids in the final impression.

3-year prospective multicenter study on one-stage implant surgery and early loading in the edentulous mandible

BACKGROUND

The long-term success rates achieved in dental implantology suggest that flexibility might well exist within the various implant systems to a degree that an altered protocol (ie, one-stage surgery and immediate or early loading) can be performed under controlled conditions. However, before variations of the protocol can be considered for general use, they must be subjected to critical analysis, particularly with respect to the predictability of osseointegration, alteration of soft tissue barrier, and relative change in bone height around the implants.

PURPOSE

The aim of this prospective multicenter study was to evaluate implant survival and periimplant conditions around endosseous implants placed in a one-stage surgical procedure and early loading.

MATERIALS AND METHODS

A total of 170 implants were placed in 40 patients with mandibular edentulism and were functionally loaded within 6 weeks with overdentures (n = 30) or fixed prostheses (n = 10). All patients and prosthetic constructions were evaluated according to a standardized protocol during 3 years of follow-up. Cumulative implant survival rates were calculated, and implant loss in relation to implant size and bone quality and quantity were evaluated. Furthermore, the protocol included assessment of clinical (plaque and bleeding scores, prosthesis stability) and radiographic parameters.

RESULTS

Over a period of 3 years, the implant survival rate was 93% for both implants and prostheses (fixed or removable). No implants were lost after the first year of loading. The periimplant tissues were in a healthy condition. Mean marginal bone resorption from the time of loading to the 3-year follow-up was 0.41 mm (SD 0.52).

CONCLUSIONS

From this study it may be concluded that early loading results in good implant survival and proper periimplant health in edentulous mandibles.

Bilateral investigation of the temporomandibular joint. An autopsy study of edentulous individuals

Investigations concerning normal and pathological anatomy of the temporomandibular joint (TMJ) have shown that pathological reactions such as deviations of the shape of the condyle, disc thinnings, disc perforations and osteoarthrotic changes are fairly common, particularly in the elderly population. Autopsy studies of the TMJ describe pathological findings respective to their location in different age groups, but most authors describe their findings for removed joints of one side only. The specific aim of this study was therefore to investigate the intra-individual relationships between the degenerative changes and deviations concerning the articular surfaces of the TMJs and the topographical distributions of these findings. In this investigation both joints of 22 edentulous individuals between 58 and 95 years of age were studied. Correlations were found between the right and left joints with respect to the anatomical location of the pathological findings.

Quantitative analysis of masseter and temporalis EMGs: a comparison of anterior guided versus balanced occlusal concepts in patients wearing complete dentures

The lack of easily measurable, objective physiological activity parameters of the masseter and temporalis muscle during jaw movements in humans has led to the consideration to revise data of surface electromyographies (EMGs) by applying a computerized quantification method. The aim of this follow-up analysis was to get quantitative data out of EMG-records of an earlier study. These records were obtained with two different splints, splint 1 providing an anterior front-canine guidance and splint 2 providing bilateral balanced occlusion. Utilizing a computer aided integration method led to numeric results which statistically proves the prediction of the previous investigation. Applying the integration method, the EMG raw signal was transformed into area-values which enabled a statistical work up of the data. Wilcoxon test statistics shows a significant (P<0.05) lower muscle activity in patients wearing dentures providing anterior front-canine guidance compared to those with balanced occlusion. It is concluded that the neuromuscular activity of the elevator muscles is highly reproducible and that the neuromuscular function is similar in edentulous subjects to that found in people with natural teeth. Furthermore, the study statistically proves earlier visual data that all those subjects, whose muscle activities were observed with anterior guidance (splint 1) compared to bilateral balanced occlusion (splint 2) showed significantly lower values with regard to subjects wearing splint 2.

Masseter and temporalis surface electromyography in patients wearing complete dentures comparing anterior and posterior occlusal concepts--a pilot study

The activity of jaw elevator muscles (masseter and anterior temporal muscle) was studied by surface electromyography in 17 patients wearing complete dentures with anterior-canine guidance. Baseline electromyography was recorded with the dentures and compared to recordings obtained with two different splints adapted to the upper denture, one providing anterior guidance leading to immediate disclusion of the posterior teeth during any jaw movement, the other providing posterior guidance buccally on the working side and lingually on the non-working side (bilaterally balanced occlusion). Recordings were obtained during a sequence of different jaw movements: postural position, maximal tooth contact in intercuspal position, protrusive movement of the mandible (under tooth contact) and during lateral excursions, also carried out under tooth contact. Muscle activity was not significantly different as recorded with dentures only versus with the splints providing anterior guidance. However, a significant increase in activity was observed with bilaterally balanced occlusion. The results of this study in edentulous people are similar to those found in patients with natural teeth.

[Cephalometric analysis of Class III patients after surgery]

The University of Innsbruck, Department of Dentistry, analysed the cephalograms of 23 prognathic patients whose dysgnathia was corrected by an osteotomy of the mandible only. The obtained results were compared with an analysis of the respective models. Documentation was obtained prior to surgery, post-operatively and during follow-up examinations over a period of at least six years. Evaluation of the results focused on occlusion and the WITS-appraisal. Prior to surgery 21 patients presented with a macromandibulosis which in 50 percent of the cases was combined with a micro- or retromaxillosis. As a rule, there were also dento-alveolar compensations with retrusion of the lower front teeth and protrusion of the anterior maxillary teeth. Surgical results remained stable in 14 cases, three patients incurred a slight partial relapse while six patients had a significant relapse, though the original extend of the malocclusion with anterior crossbite reoccurred in two cases only. It was possible to prove the relationship between relapse and the existence of myofunctional disturbances. Consequently, safe long-term results may only be obtained by means of interdisciplinary planning and treatment.

The mandibular condyles in the submentovertex projection--their morphology and topographical relationship to the foramina spinosa

On conventional radiographs, the morphology and position of the condyles in an axial view are best seen in the submentovertex projection. The foramina spinosa, which are used by the middle meningeal arteries as passages and are clearly outlined in this view, serve as landmarks for a co-ordinate system that permits precise measurements of various angles and distances. One hundred and twenty-six submentovertex views were used for measuring the condyles. Results presented as means and standard deviations suggest condylar variables to be related to the function of the stomatognathic system. Practical applications include surgical, orthodontic or prosthetic manipulations of the mandible resulting in transverse or sagittal displacement of the condyles.