The effect of combined surgery and physiotherapy on the facial asymmetry in patients with congenital muscular torticollis: a retrospective cohort study

The aim of this study was to assess the influence of surgical therapy, intraoperative evaluation, and immediate physiotherapy on the facial asymmetry of patients with congenital muscular torticollis (CMT). Patients who underwent a combination of unipolar sternocleidomastoid muscle release with perioperative physiotherapy between 2014 and 2020 in the Department of Oral and Maxillofacial Surgery, Radboud University Medical Center, Nijmegen were enrolled. Three-dimensional photographs of the face acquired 2 months preoperatively and 1.5-2 years postoperatively were assessed. Based on 43 patients, there was a significant improvement in the asymmetry indices (angles between bilateral exocanthion, bilateral cheilion, and nasion-gnathion lines): mean ± standard deviation reductions in indices (Ex-Ex)-(Ch-Ch), (Ex-Ex)-(Na-Gn), and (Ch-Ch)-(Na-Gn) of 0.88 ± 1.08° (P < 0.001), 1.04 ± 1.26° (P < 0.001), and 0.21 ± 1.06° (P = 0.024), respectively. Analysis of covariance (ANCOVA) showed that intervention at an early age (P = 0.017) and left-sided torticollis (P = 0.030) were associated with a significantly greater improvement in the facial asymmetry. This study found that the use of combined surgery and physiotherapy reduced the facial asymmetry of patients with CMT at 2 years postoperatively. Early intervention and left-sided torticollis were associated with a greater improvement in the facial asymmetry. This indicates that attention should be given to early intervention and right-sided CMT cases postoperatively.

Challenges in conducting clinical research in primary care dentistry

The integration of dentistry into primary health care is crucial for promoting patient well-being. However, clinical studies in dentistry face challenges, including issues with study design, transparency, and relevance to primary care. Clinical trials in dentistry often focus on specific issues with strict eligibility criteria, limiting the generalizability of findings. Randomized clinical trials (RCTs) face challenges in reflecting real-world conditions and using clinically relevant outcomes. The need for more pragmatic approaches and the inclusion of clinically relevant outcomes (CROs) is discussed, such as tooth loss or implant success. Solutions proposed include well-controlled observational studies, optimized data collection tools, and the integration of artificial intelligence (AI) for predictive modelling, computer-aided diagnostics and automated diagnosis. In this position paper advocates for more efficient trials with a focus on patient-centred outcomes, as well as the adoption of pragmatic study designs reflecting real-world conditions. Collaborative research networks, increased funding, enhanced data retrieval, and open science practices are also recommended. Technology, including intraoral scanners and AI, is highlighted for improving efficiency in dental research. AI is seen as a key tool for participant recruitment, predictive modelling, and outcome evaluation. However, ethical considerations and ongoing validation are emphasized to ensure the reliability and trustworthiness of AI-driven solutions in dental research. In conclusion, the efficient conduct of clinical research in primary care dentistry requires a comprehensive approach, including changes in study design, data collection, and analytical methods. The integration of AI is seen as pivotal in achieving these objectives in a meaningful and efficient way.

Does facial asymmetry vary between subjects of different age groups? A 3D stereophotogrammetry analysis

This study was aimed to assess whether facial asymmetry increases with age and to examine potential gender differences using 3D stereophotogrammetry. A prospective cross-sectional study was performed. 3D photographs were acquired from 600 control subjects, 300 male, 300 female, and were stratified into 15 different age groups ranging from 0 to 70+. The 3D photographs were postprocessed and mirrored. The original and mirrored faces were surface-based matched using an iterative closest point algorithm. The primary outcome variable, facial asymmetry, was evaluated by calculating the absolute mean distance between the original and mirrored images. The primary predictor was age. Pearson's correlation was used to assess the correlation between facial asymmetry and age. The average overall facial asymmetry was 0.72 mm (SD 0.72 mm; range 0.25 - 3.04 mm). Mean facial asymmetry increased significantly with age, from 0.45 mm in the age group of 0-4 years to 0.98 mm in the age group of 70+ (p<0.001). Facial asymmetry was positively correlated with age (Pearson's r = 0.55; p<0.001). Male subjects were significantly more asymmetric compared to females, 0.77 mm and 0.67 mm, respectively (p<0.001). This study indicates that facial asymmetry significantly increases with age and is significantly larger in males than in females.

[The 3D-printed surgical guides used during genioplasty]

Genioplasty is a seemingly simple procedure performed to correct the bony chin. The results of the procedure are, however, strongly correlated with the experience of the surgeon. 3D-printed surgical guides could act as a transfer modality to translate the preoperative planning directly into the achieved result. Prospective studies evaluating the usefulness of the 3D-printed surgical guides have not yet been carried out and consensus regarding the best design is lacking. In order to become more familiar with working with surgical guides, a genioplasty using 3D-printed surgical guides was performed. The postoperative analysis of the achieved result showed minor differences compared to preoperative planning. Surgical guides have the potential to improve the accuracy and predictability of genioplasty. The design should be further refined and the added value of the guides should be confirmed by means of prospective research.

[Reconstruction after facial trauma with dento-alveolar injury]

While abroad, a healthy 36-year-old woman slammed head-on into a rock wall at high speed, resulting in significant facial trauma. The initial trauma care and first aid took place abroad. In the Netherlands, the woman was referred to the Department of Oral and Maxillofacial Surgery (OMFS) for reconstruction of her face and alveolar processes, gingiva and dentition. In view of the seriousness of the injuries, a 3D treatment plan was drawn up in a multidisciplinary collaboration with an OMF surgeon, an implantologist, dentist and dental technician. By making a digital setup of both the top and bottom front in advance, it was possible to work predictably. The first step consisted of bone augmentation by means of an iliac crest graft to reconstruct the major bone defects of the superior and inferior alveolar processes. Implants were then placed in the upper and lower jaws in the ideal position for the suprastructure by means of drill jigs. Within 10 months after the trauma, the implant bridges could be placed on individual zirconia frameworks to optimally restore oral function and aesthetics, completing the reconstruction.

Surgical accuracy in 3D planned bimaxillary osteotomies: intraoral scans and plaster casts as digital dentition models

The aim of this study was to assess whether the use of intraoral scans (IOS) is an eligible alternative to conventional plaster casts in terms of surgical accuracy of three-dimensionally planned bimaxillary osteotomies. This retrospective cohort study included patients who underwent bimaxillary surgery between 2016 and 2020 in the Department of Oral and Maxillofacial Surgery at Radboud University Medical Center, Nijmegen. Three-dimensional virtual planning was performed with the use of plaster casts in one group and IOS in the other group. Cone beam computed tomography scans were acquired preoperatively and at 1 week following surgery. By using voxel-based matching, the maxillary movements were quantified in six degrees of freedom. The primary outcome variable, surgical accuracy, was defined as the difference between the planned maxillary movements and those achieved. Of 152 patients, 113 were documented with plaster casts and 39 with IOS. The surgical accuracy was comparable in terms of maxillary vertical, sagittal, and transverse translations, as well as roll and yaw. Maxillary pitch (difference 0.55 ± 0.26°; P = 0.001) was in favour of the IOS group. This study demonstrated that IOS can be used as an alternative to conventional plaster casts in the three-dimensional planning of bimaxillary osteotomies.

Virtual occlusion in orthognathic surgery

The aim of this retrospective study was to determine whether a virtually created occlusion is as accurate as a conventionally created occlusion. Seventeen orthognathic patients were included in the study, which was conducted in a university clinic. Plaster cast models were obtained and digitized. Two experienced observers created the conventional (gold standard) and virtual occlusion to assess inter-observer variability. One observer created the conventional and virtual occlusion a second time to assess the intra-observer variability. The criterion for accepting the virtual occlusion was that the difference between the gold standard and the virtual occlusion was not larger than the intra-observer variability for the gold standard. A non-parametric Kruskal-Wallis H test was performed to detect statistically significant differences between the intra- and inter-observer groups for both the conventional and virtual occlusion. No statistically significant differences were found between the different groups. The difference between the conventional and virtual occlusion group was 0.20mm larger than the intra-observer variability of the gold standard. The virtual occlusion tool presented here can be utilized in daily clinical practice and makes the use of physical dental models redundant.

Three-dimensional stereophotogrammetry measurement of facial asymmetry in patients with congenital muscular torticollis: a non-invasive method

The aim of this study was to evaluate three-dimensional (3D) stereophotogrammetry based methods for measuring craniofacial asymmetry in patients with congenital muscular torticollis (CMT). This study focused on the differences in craniofacial asymmetry in CMT patients compared with a healthy control group using 3D photographs. The difference in facial asymmetry between the CMT group and control group was measured using two methods to analyse facial asymmetry in distinct anatomical regions: (1) mirroring and surface-based registration to analyse the overall facial asymmetry; (2) the 'coherent point drift' based method. Thirty-one patients with CMT and 84 controls were included in the study. A statistically significant difference was found between the CMT patients and a healthy control group. The measured facial asymmetry for the CMT group was 1.71±0.66mm and for the controls 0.46±0.14mm (P<0.05). A significant difference was found in surface ratio for the cheek, nose and the forehead region (P<0.05). With its minimal invasive character, 3D stereophotogrammetry is a useful tool in measuring the facial asymmetry associated with CMT and to quantify the treatment-induced facial changes. In the future 3D facial data could be used to create a ranking-scale to categorize the severity of facial asymmetry.

The use of xenografts to prevent inferior border defects following bilateral sagittal split osteotomies: three-dimensional skeletal analysis using cone beam computed tomography

The aim of this retrospective study was to investigate grafting in the osteotomy gap during bilateral sagittal split osteotomy (BSSO), using a xenograft and fibrin glue. Hard tissue defects in the inferior mandibular border were assessed using cone beam computed tomography scans taken 1 week and 1year postoperatively. The study group of 20 patients underwent bone grafting during BSSO (mean age 26.1years; mean horizontal displacement 8.5mm) and the control group of 20 patients did not (mean age 30.2 years; mean horizontal displacement 7.6mm). The mean height of the mandibular defects was significantly lower in the study group, but there was no significant difference in volume measurements between the groups. Grafting had a negligible effect on large displacements (9.0-15.0mm), which might have been due to an inadequate amount and/or positioning of the graft, or to poor dimensional stability. This may be resolved by improved graft positioning or by using a different kind of (xeno)graft.

Virtual setup in orthodontics: planning and evaluation

OBJECTIVES

The purpose of this study was to evaluate the clinical accuracy of virtual orthodontic setups by using a new CBCT-based approach.

MATERIALS AND METHODS

Ten patients who underwent pre-surgical orthodontics were included in this study. Pre-treatment and pre-surgical cone-beam CT (CBCT) scans and digital dental models were available. The pre-treatment digital dental model was used to create an orthodontic virtual setup. The digital dental models were fused with the corresponding CBCT scans, and the two CBCT scans were aligned using voxel-based matching. Moving each individual tooth from the virtual setup to the final outcome allows the calculation of the accuracy of the virtual setup by using an iterative closest point algorithm. Differences between virtual setup and final outcome were recorded as well as the ICC between two observers.

RESULTS

The inter-observer variability showed a high level of agreement between the observers. The largest mean difference between observers was found in the cranial/caudal direction (0.36 ± 0.30 mm) and the roll rotation (1.54 ± 0.98°). Differences between the virtual setup and final outcome were small in the translational direction (0.45 ± 0.48 mm). Rotational mean differences were larger with the pitch of the incisors (0.00 ± 7.97°) and molars (0.01 ± 10.26°) as largest difference. Excessive extrusion of all upper teeth and more anterior movement than planned were seen for both upper and lower arch. Lower molars showed less extrusion.

CLINICAL RELEVANCE

The data of this study can be used to obtain more insight in the accuracy and achievability of orthodontic virtual setup. Tooth movement can now be studied in more details which can lead to new insights.

Effect of skin tone on the accuracy of hybrid and passive stereophotogrammetry

BACKGROUND

Three-dimensional (3D) surface images acquired from stereophotogrammetry are increasingly being used to plan or evaluate treatment by plastic surgeons. Stereophotogrammetry exists in active, passive, and hybrid forms. Active and hybrid stereophotogrammetry are believed to capture darker surfaces more accurately than passive stereophotogrammetry. The purpose of this study was to investigate whether skin tone has a clinically relevant effect on the accuracy of hybrid and passive stereophotogrammetry.

MATERIALS AND METHODS

Seven subjects with different skin tones were recruited. 3D-printed face and breast were spray-painted in six different colors, ranging from white to black. The skin tones and paint colors were objectified by measuring their melanin index. 3D photos of the subjects and 3D prints were acquired with hybrid and passive stereophotogrammetry. These 3D photos were matched with specialized software, and their geometric differences were calculated.

RESULTS

None of the 3D photos showed a clinically relevant mean inaccuracy. On the 3D prints, hybrid stereophotogrammetry resulted in a smaller standard deviation of the inaccuracies than passive stereophotogrammetry (0.20 ± 0.06 mm vs. 0.35 ± 0.07 mm, p < 0.001). Passive stereophotogrammetry yielded a correlation between the melanin index of the spray paint colors and the standard deviation of the inaccuracy (Pearson's R = 0.60, p = 0.04). On human subjects, no correlation or difference in standard deviation of the accuracy was found.

CONCLUSION

Skin tone does not influence the accuracy of hybrid and passive 3D stereophotogrammetry in a clinically relevant way.

Reliability and accuracy of cone beam computed tomography versus conventional multidetector computed tomography for image-guided craniofacial implant planning: An in vitro study

PURPOSE

To assess the reliability and accuracy of linear measurements on three-dimensional (3D) cross-sectional images, both acquired with cone beam computed tomography (CBCT) and multi-detector row CT (MDCT). Bone thickness was evaluated with regard to image-guided planning of craniofacial implant surgery.

MATERIALS AND METHODS

Five dry human skulls were used. Cuts were made with a circular bone saw at the ideal implant positions in the nasal, orbital, and temporal regions prior to acquisition of CBCT and MDCT scans. After imaging examination, bone width was assessed by three independent observers using a caliper and defined as a reference. In the next step, cross-sectional images of the regions with the aforementioned cuts were reconstructed from 3D virtual models generated from the digital DICOM datasets with the use of 3D image-based planning software. Subsequently, linear measurements were performed. The systematic difference and interobserver and intraobserver variation of MDCT and CBCT linear measurements were compared with the physical measurements at different locations in the nasal, orbital, and temporal region, respectively. Also, the potential influence of different gray-level values was investigated. The quantitative accuracy of distance measurements was performed using a two-way analysis of variance (ANOVA) and variance component analyses. Only differences with P values < .05 were considered significant.

RESULTS

All radiologic measurements showed a significant overestimation of the bony dimensions, reaching more than the used voxel sizes of 0.3 mm for CBCT and 0.5 mm for MDCT. For CBCT, an average measurement bias of 0.39 to 0.53 mm and for MDCT of 0.57 to 0.59 mm was found. MDCT images showed less interobserver variation in linear measurements on cross-sectional images from 3D virtual models compared with CBCT images. Contrast settings statistically significantly influenced linear measurements of bone width for CBCT images (P < .0015) and interobserver variation on MDCT imaging (P < .029).

CONCLUSION

Both CBCT images (KaVo 3D eXam Imaging System) and MDCT images (Aquilion ONE, Toshiba) showed a highly consistent submillimeter overestimation of the anatomical truth in assessing bone thickness of nasal, orbital, and temporal regions of ex vivo specimens. When using CBCT and MDCT images for presurgical assessment, one should be aware of the overestimation of the cortical bone thickness.

New software and breast boundary landmarks to calculate breast volumes from 3D surface images

Background

A method to accurately calculate breast volumes helps achieving a better breast surgery outcome. 3D surface imaging potentially allows these calculations in a harmless, quick, and practicable way. The calculated volume from a 3D surface image is dependent on the determined breast boundary and the method of chest wall simulation by software. Currently, there is no consensus on a robust set of breast boundary landmarks and validation studies on breast volume calculation software are scarce. The purposes of this study were to determine the robustness of newly introduced breast boundary landmarks and introduce and validate a new method to simulate a chest wall.

Methods

Sixteen subjects who underwent a unilateral simple mastectomy were included. In addition to the natural skin fold of the breast, the sternomanubrial joint, the transition of the pectoral muscle curve into the breast curvature, and the midaxillary line were used as landmarks to indicate the breast boundary. The intra- and interrater variability of these landmarks was tested. Furthermore, new chest wall simulation software was validated on the breastless chest side of the subjects.

Results

The intra- and interrater variability of the three breast boundary markers was small (mean 3.5–6.7 mm), and no significant difference was found between the intra- and interrater variability (p = 0.08, p = 0.06, and p = 0.10). The mean volume error of the most accurately simulated chest wall was 4.6 ± 37 ml.

Conclusion

The newly introduced landmarks showed to be robust and our new chest wall simulation algorithm showed accurate results.

Level of Evidence: Level IV, diagnostic study.

Dentition Patterns in Different Unilateral Cleft Lip Subphenotypes

Oral clefts play an essential role in disturbed odontogenesis of the deciduous and permanent dentition, yet little is known about this relationship. We investigated, within the categories cleft lip with or without alveolus (CL ± A) and cleft lip, alveolus and palate (CLAP), whether different CL subphenotypes based on morphological severity of the cleft show different dentition patterns and whether a more detailed subdivision of the incomplete CL has clinical relevance. In this retrospective study, 345 children with nonsyndromic unilateral CL ± A and CLAP from the Dutch Association for Cleft Palate and Craniofacial Anomalies (NVSCA) registry were included to assess the association between the CL subphenotypes and lateral incisor patterns. Five different deciduous and permanent patterns of the lateral incisor were distinguished: located in normal position (pattern z/Z), in the anterior segment (pattern x/X) or in the posterior segment of the cleft (pattern y/Y), one in each segment of the cleft (pattern xy/XY), and agenesis of the lateral incisor (pattern ab/AB). Analyses were performed by using multinomial logistic regression models. Children born with a vermillion notch or a one-third to two-thirds CL were most likely to have a deciduous pattern x and a permanent pattern X, while children born with a two-thirds to subtotal CL were most likely to have deciduous pattern xy and a permanent pattern X compared to children with a complete CL that predominantly had deciduous pattern y and a permanent pattern AB. Based on the relationship of the CL morphology with the deciduous dentition, subdivision of the CL morphology into vermillion notch to two-thirds CL, two-thirds to subtotal CL, and complete CL appears to be an optimal subdivision. Our results indicate that a more detailed subdivision of the CL has clinical relevance and that critical factors in the pathogenesis of the CL are also critical for the odontogenesis.

An accuracy study of computer-planned implant placement in the augmented maxilla using osteosynthesis screws

Previous research on the accuracy of flapless implant placement of virtually planned implants in the augmented maxilla revealed unfavourable discrepancies between implant planning and placement. By using the osteosynthesis screws placed during the augmentation procedure, the surgical template could be optimally stabilized. The purpose of this study was to validate this method by evaluating its clinically relevant accuracy. Twelve consecutive fully edentulous patients with extreme resorption of the maxilla were treated with a bone augmentation procedure. Virtual implant planning was performed and a surgical template was manufactured. Subsequently, six implants were installed using the surgical template, which was only supported by the osteosynthesis screws. Implant deviations between planning and placement were calculated. A total of 72 implants were installed. Mean deviations found in the mesiodistal direction were 0.817mm at the implant tip and 0.528mm at the implant shoulder. The angular deviation was 2.924°. In the buccolingual direction, a deviation of 1.038mm was registered at the implant tip and 0.633mm at the implant shoulder. The angular deviation was 3.440°. This study showed that implant placement in the augmented maxilla using a surgical template supported by osteosynthesis screws is accurate.

Three-dimensional virtual simulation of alar width changes following bimaxillary osteotomies

The aim of this study was to evaluate the accuracy of three-dimensional (3D) soft tissue simulation of nose width changes following bimaxillary osteotomies and to identify patient- and surgery-related factors that may affect the accuracy of simulation. Sixty patients (mean age 26 years) who underwent bimaxillary osteotomies participated in this study. Cone beam computed tomography scans were acquired preoperatively and at 1-year postoperative. The 3D hard and soft tissue rendered preoperative and postoperative virtual head models were superimposed, after which the maxilla and mandible were segmented and aligned to the postoperative position. The postoperative changes in alar width were simulated using a mass tensor model (MTM)-based algorithm and compared with the postoperative outcome. 3D cephalometric analyses were used to quantify the simulation error. The postoperative alar width was increased by 1.6±1.1mm and the mean error between the 3D simulation and the actual postoperative alar width was 1.0±0.9mm. The predictability was not correlated to factors such as age, sex, alar cinch suture, VY closure, maxillary advancement, or a history of surgically assisted rapid maxillary expansion. The MTM-based simulation model of postoperative alar width change was found to be reasonably accurate, although there is room for further improvement.

Three-dimensional evaluation of the alar cinch suture after Le Fort I osteotomy

Orthognathic surgery has an influence on the overlying soft tissues of the translated bony maxillomandibular complex. Improvements in both function and facial appearance are the goals of surgery. However, unwanted changes to the soft tissues, especially in the nose region, frequently occur. The most common secondary change in the nasolabial region is widening of the alar base. Various surgical techniques have been developed to minimize this effect. The purpose of this study was to evaluate the changes in the nasal region due to orthognathic surgery, especially the alar width and nasal volume, using combined cone beam computed tomography (CBCT) and three-dimensional (3D) stereophotogrammetry datasets. Twenty-six patients who underwent a Le Fort I advancement osteotomy between 2006 and 2013 were included. From 2006 to 2010, no alar base cinch sutures were performed. From 2010 onwards, alar base cinch sutures were used. Preoperative and postoperative documentation consisted of 3D stereophotogrammetry and CBCT scans. 3D measurements were performed on the combined datasets, and the alar base width and nose volume were analyzed. No difference in alar base width or nose volume was observed between patients who had undergone an alar cinch and those who had not. Postoperatively the nose widened and the volume increased in both groups.

Postoperative socket irrigation with drinking tap water reduces the risk of inflammatory complications following surgical removal of third molars: a multicenter randomized trial

Objectives

The primary aim of the present study was to evaluate the effectiveness of postoperative irrigation of the socket with drinking tap water on inflammatory complications following lower third molar removal.

Material and methods

A multicenter randomized controlled trial was carried out from June 2013 to June 2014. In one arm of the study, patients were instructed to irrigate the tooth socket and surgical site with a Monoject® Curved 412 Tip Syringe (Tyco/healthcare-Kendall, Mansfield, MA, USA) with tap water. In a second arm of the study, the standard postoperative instructions did not include irrigation instructions. The incidences of alveolar osteitis and wound infection were recorded for each group and analyzed by the Fisher’s exact test.

Results

A total of 280 patients with 333 mandibular third molars were analyzed. According to the intention-to-treat (ITT) analysis, inflammatory complications occurred in 18 cases in the Monoject® group (11.4 %) compared to 34 cases (19.1 %) in the control group (p = 0.04). These complications were associated with significant worse outcomes regarding quality of life, pain, and trismus and caused significantly more missed days of work or study. Female gender, age >26, bone removal, deep impacted third molars, less experienced surgeons, and a high amount of debris at the surgical site were also identified as risk factors for developing inflammatory complications following lower third molar removal.

Conclusion

Irrigation of the surgical site with drinking tap water using a curved syringe following removal of third molars is effective in reducing the risk of inflammatory complications.

Clinical relevance

Water is a very accessible, cost-effective irrigant without side effects and the results from this study have proven that it can be used to reduce the risk of inflammatory complications and associated morbidity following lower third molar removal.

Three-dimensional facial analysis in acromegaly: a novel tool to quantify craniofacial characteristics after long-term remission

PURPOSE

The exact quantification of craniofacial characteristics in patients with acromegaly is important because it provides insight in the pathophysiology of the disease and offers a tool to evaluate the effects of treatment on tissue specific endpoints. However, until recently this was not feasible due to limitations of available cephalometric methods. The new technique of three-dimensional (3D) cephalometry enables the accurate quantification of facial anatomical characteristics of both soft tissue and bone. This is the first study that uses 3D cephalometry to analyze craniofacial disproportions in patients in long-term remission of acromegaly.

METHODS

Sixteen patients in remission of acromegaly for over 24 months (50% male, mean age 56.0 ± 10.7 years, mean body mass index 29.3 ± 5.5 kg/m(2)) were compared to 16 matched control subjects. A 3D cone beam computed tomography scan and 3D stereophotograph of each individual were acquired and analyzed using 3D cephalometry.

RESULTS

In addition to an accurate quantification of the classical craniofacial characteristics, 3D cephalometry, shows that many typical soft tissue deformities persist, even after long-term remission. Furthermore, we found that, compared to controls, the patients in remission of acromegaly have a wider face at the level of the zygoma and longer maxilla (p < 0.05).

CONCLUSIONS

3D cephalometry is an attractive novel imaging modality to accurately investigate craniofacial disproportions of both soft tissue and bony parts of the face in patients with acromegaly, which makes it a promising technique for future research purposes and clinical practice.

Three-dimensional changes in nose and upper lip volume after orthognathic surgery

Orthognathic surgery aims to improve both the function and facial appearance of the patient. Translation of the maxillomandibular complex for correction of malocclusion is always followed by changes to the covering soft tissues, especially the nose and lips. The purpose of this study was to evaluate the changes in the nasal region and upper lip due to orthognathic surgery using combined cone beam computed tomography (CBCT) and three-dimensional (3D) stereophotogrammetry datasets. Patients who underwent a Le Fort I osteotomy, with or without a bilateral sagittal split osteotomy, were included in this study. Pre- and postoperative documentation consisted of 3D stereophotogrammetry and CBCT scans. 3D measurements were performed on the combined datasets and analyzed. Anterior translation and clockwise pitching of the maxilla led to a significant volume increase in the lip. Cranial translation of the maxilla led to an increase in the alar width. The combination of CBCT DICOM data and 3D stereophotogrammetry proved to be useful in the 3D analysis of the maxillary hard tissue changes, as well as changes in the soft tissues. Measurements could be acquired and compared to investigate the influence of maxillary movement on the soft tissues of the nose and the upper lip.

Validation of a novel semi-automated method for three-dimensional surface rendering of condyles using cone beam computed tomography data

Morphological changes of the condyles are often observed following orthognathic surgery. In addition to clinical assessment, radiographic evaluation of the condyles is required to distinguish the physiological condylar remodelling from pathological condylar resorption. The low contrast resolution and distortion of greyscale values in cone beam computed tomography (CBCT) scans have impeded an accurate three-dimensional (3D) rendering of the condyles. The current study proposes a novel semi-automated method for 3D rendering of condyles using CBCT datasets, and provides a clinical validation of this method. Ten patients were scanned using a standard CBCT scanning protocol. After defining the volume of interest, a greyscale cut-off value was selected to allow an automatic reconstruction of the condylar outline. The condylar contour was further enhanced manually by two independent observers to correct for the under- and over-contoured voxels. Volumetric measurements and surface distance maps of the condyles were computed. The mean within-observer and between-observer differences in condylar volume were 8.62 mm(3) and 6.13 mm(3), respectively. The mean discrepancy between intra- and inter-observer distance maps of the condylar surface was 0.22 mm and 0.13 mm, respectively. This novel method provides a reproducible tool for the 3D rendering of condyles, allowing longitudinal follow-up and quantitative analysis of condylar changes following orthognathic surgery.

[Progress in the studies on the evaluation of biocompatibility of biomaterials]

Biocompatibility remains the central theme for biomaterials applications in medicine. It generally refers to the compatibility between the biomaterials and the receptor, including tissue-compatibility and blood-compatibility. The definition of the biocompatibility has been greatly changed in recent years; it is now accepted as involving two principle areas, one is the principle of 'biosafety', the second is the principle of 'biofunctionality'.

A common variant in PPP1R3 associated with insulin resistance and type 2 diabetes

Selected candidate genes have been analyzed in the Pima Indians of Arizona based on evidence that insulin resistance and type 2 diabetes have significant genetic determinants. An amino acid substitution at codon 905 of the glycogen-targeting subunit of type 1 protein phosphatase that regulates skeletal muscle glycogenesis was recently reported to be associated with changes in insulin action in Danish subjects. In addition to the variant at 905, we report here a novel substitution at codon 883 and common variant of an "ATTTA" element in the 3'-untranslated region (UTR) of the corresponding gene (PPP1R3). The 3'-UTR variant resembled the mRNA-destabilizing AT(AU)-rich elements (AREs) and resulted in a 10-fold difference in reporter mRNA half-life, was correlated with PPP1R3 transcript and protein concentrations in vivo, and was associated with insulin resistance and type 2 diabetes in the Pimas. The variant is more common in Pimas (0.56) than in Caucasians (0.40). Because of its apparent effect on expression of PPP1R3, it may, in part, contribute to the higher prevalence of type 2 diabetes in this Native American population.

Human PON2 gene at 7q21.3: cloning, multiple mRNA forms, and missense polymorphisms in the coding sequence

We report the cloning and characterization of human PON2, a paraoxonase-related gene-2 that is physically linked with PON1 and PON3 on 7q2l.3. PON2 is ubiquitously expressed and we identified several mRNA forms produced by alternative splicing, or by the use of a second transcription start site. We also describe two polymorphisms in the coding sequences that, in the protein deduced from the longest open reading frame, predict an alanine-to-glycine substitution at residue 147 and a serine-to-cysteine substitution at residue 310.

Prediction of mutant activity and its application in molecular design of tumor necrosis factor-alpha

Two models for prediction of the activity and stability of site-directed mutagenesis on tumor necrosis factor-alpha are established. The models are based on straightforward structural considerations, which do not require the elaboration of sitedirected mutagenesis on the protein core and the hydrophobic surface area by analyzing the pmperties of the mutated amino acid residues. The reliabilities of the models have been tested by analyzing the mutants of tumor necrosis factor-alpha (TNF-alpha) whose two leucine residues (L29, L157) were mutated. Based on these models, a TNFalpha mutant with high activity was created by molecular design.

Cloning and characterization of PDK4 on 7q21.3 encoding a fourth pyruvate dehydrogenase kinase isoenzyme in human

Different isoenzymes of pyruvate dehydrogenase kinase (PDK) inhibit the mitochondrial pyruvate dehydrogenase complex by phosphorylation of the E1alpha subunit, thus contributing to the regulation of glucose metabolism. By positional cloning in the 7q21.3-q22.1 region linked with insulin resistance and non-insulin-dependent diabetes mellitus in the Pima Indians, we identified a gene encoding an additional human PDK isoform, as evidenced by its amino acid sequence identity (>65%) with other mammalian PDKs, and confirmed by biochemical analyses of the recombinant protein. We performed detailed comparative analyses of the gene, termed PDK4, in insulin-resistant and insulin-sensitive Pima Indians, and detected five DNA variants with comparable frequencies in both subject groups. Using quantitative reverse transcription polymerase chain reaction, we found that the variants identified in the promoter and 5'-untranslated region did not correlate with differences in mRNA level in skeletal muscle and adipose tissue. We conclude that alterations in PDK4 are unlikely to be the molecular basis underlying the observed linkage at 7q21.3-q22.1 in the Pima Indians. Information about the genomic organization and promoter sequences of PDK4 will be useful in studies of other members of this family of mitochondrial protein kinases that are important for the regulation of glucose metabolism.

Biological activities of human tumor necrosis factor-alpha and its novel mutants

Biological activities of human tumor necrosis factor-alpha (hTNF-alpha) and its mutants were compared. In cytotoxicity assay with L929 cells, one mutant, designated as TNF-B, showed 4.5-fold higher activity than TNF examined. In receptor binding assay, TNF-B had almost the same affinity for TNF receptors on L929 cells as hTNF-alpha. We also found that TNF-B retained the cytotoxicity of hTNF-alpha for HEp-2 cells. TNF-B also had two-fold higher affinity than hTNF-alpha for receptors on HEp-2 cells (only carrying hTNF-R55) and lower affinity for receptors on U937 cells (expressing mainly hTNF-R75). These results suggested that TNF-B might still interact with the human TNF-R55 receptor, but it might largely lose its ability to bind to human TNF-R75. Changes of biological activity of TNFs might be due to an altered affinity to the different types of TNF receptor on the target cells.

Effects of menidipine on dihydropyridines binding sites in cardiac and cerebral membranes from old rats with left ventricular hypertrophy

AIM

To study the effects of menidipine (Men) on the affinity and density of dihydropyridines (DHP) binding sites in the cell membranes of left ventricle (LV) and brain in elderly renovascular hypertensive rats (RVHR) with LV hypertrophy.

METHODS

Renovascular hypertension was produced by clipping the left renal artery in 20-month-old rats. The affinity and density of DHP binding sites in the cell membranes of LV and brain were assessed by radioligand assay.

RESULTS

Men (20 mg.kg-1.d-1 ig for 9 wk) decreased markedly the systolic blood pressure and the LV weight (P < 0.01). Though not affecting the density of DHP receptor (Bmax), Men markedly decreased the total number of DHP binding sites in hypertrophied LV (from 5.95 +/- 0.62 to 4.0 +/- 1.1 pmol.LV). Men also reduced Bmax of DHP binding sites in the thalamus (from 522 +/- 27 to 371 +/- 24 pmol/g protein) and hippocampus (from 498 +/- 26 to 332 +/- 32 pmol/g protein).

CONCLUSION

Men reversed the LV hypertrophy from renovascular hypertension accompanied with reduced total number of DHP binding sites in the cell membranes of LV and Bmax of the cell membranes of thalamus and hippocampus from elderly LV hypertrophied rats.

Biological activities of human tumor necrosis factor-alpha and its novel mutants

Biological activities of human tumor necrosis factor-alpha (hTNF-alpha) and its mutants were compared. In cytotoxicity assay with L929 cells, one mutant, designated as TNF-B, showed 4.5-fold higher activity than TNF examined. And TNF-B also increased cytostatic activity and decreased protein synthesis against U937 cells. In receptor binding assay, TNF-B had almost the same affinity for TNF receports on L929 cells as hTNF-alpha. But another mutant, TNFarg, markedly decreased the all activities of hTNF-alpha and had lower affinity for receports on different types of target cell. These results indicated that the relative activity of TNFs to target cells may correlate with their affinity for receports. We also found that TNF-B retained the cytotoxicity of hTNF-alpha for HEp-2 cells. TNF-B also had two-fold higher affinity than hTNF-alpha for receptors on HEp-2 cells (only carrying hTNF-R55) and lower affinity for receptors on U937 cells (expressing mainly hTNF-R75). These results suggested that TNF-B might still interact with the human TNF-R55 receptor, but it might largely lose its ability to bind to human TNF-R75. Changes of biological activity of TNFs might be due to an altered affinity to the different types of TNF receptor on the target cells.

Degradation of polyetherurethane by subcutaneous implantation into rats. II. Changes of contact angles, infrared spectra, and nuclear magnetic resonance spectra

In vivo degradation of polyetherurethanes (PEUs) was studied using two kinds of PEUs, U-3 and U-8, coated on a base film of ethylene/vinyl alcohol copolymer (EVAL). U-3 is a nonsegmented PEU prepared from 4,4'-diisocyanatodiphenylmethane (MDI) and poly(tetramethylene oxide) (PTMO 1000). U-8 is a segmented PEU prepared from MDI, PTMO 1000, and 1,4-butanediol. Previous studies of PEUs were conducted using gel permeation chromatography and scanning electron microscopy. In this study, the explanted materials were examined with contact angle measurement, ATR-FTIR, and nuclear magnetic resonance (NMR) spectroscopies. All data obtained by these methodologies indicate that the PTMO/MDI oligomers diffused to the material surface in the early stage of implantation. Then, the low-molecular-weight fraction of the oligomers leached out from the surface to the exudate. Degradation became dominant after 2-4 weeks. In the case of PU-8, the PTMO fraction decreased approximately 35-40% from the surface at 24 weeks postimplantation. In the case of PU-3, the loss of coating material (U-3) on the base film (EVAL) was observed after 10 weeks. The PTMO fraction of the surface U-3 remained on EVAL at 6 weeks postimplantation, however, it was 64% of the initial material. The molecular weight of the U-3 remaining on EVAL also decreased. Degradation of U-3 occurred more rapidly than that of U-8. The data obtained with our materials were insufficient in determining evidence of oxidative degradation with IR or NMR spectra.

Human macrophage colony stimulating factor (HM-CSF) expressed in baculovirus infected insect cells is biologically active in its monomeric form

hM-CSF was reported to have biological activity only in a dimeric form. Using oligonucleotide-directed mutagenesis of hM-CSF (1-149aa) cDNA, we have substituted Ser31 for Cys31 which forms intermolecular disulfide bond in native hM-CSF. The mutant hM-CSF cDNA was expressed in insect BmN cells using baculovirus as a vector under the control of polyhedrin promoter. Biological activity analysis and radioligand receptor assay both showed that there was little difference between the mutant hM-CSF and the native dimeric hM-CSF. These results strongly support that the biologically active human M-CSF in its monomeric form can be expressed in recombinant baculovirus infected insect cells.

Interaction of silkworm larvae expressed monomeric hM-CSF with its receptor on murine bone marrow derived macrophage

Human macrophage colony-stimulating factor (hM-CSF) expressed in the silkworm larvae was monomeric. The nature of the interaction of iodinated monomeric M-CSF with murine bone marrow derived macrophage (BMM) was studied. On incubation with 2 nM [125I]M-CSF at 4 degrees C, approximately 90% of the maximal binding occurred within 15 min with a plateau around 1hr which then gradually declined. Scatchard plot analysis showed that the Kd for the monomeric M-CSF is 5.3 x 10(-10) M and the number of binding sites per cell is 4 x 10(4). Competition experiment indicated that cellular binding of the iodinated monomeric rhM-CSF was almost as effective as the native M-CSF. The results show that the interchain disulfide bond of M-CSF is not essential for the natural folding of active M-CSF.

[Effects of m-nifedipine and nifedipine on hemodynamics in renovascular hypertensive rats]

In the renovascular hypertensive myocardial hypertrophic rats of prevention and regressive groups, the blood pressure was lowered by m-nifedipine (m-Nif) or nifedipine (Nif) of 20 mg.kg-1.d-1, i.g., for 9 wk vs control (LVH) group (P < 0.01). From the isolated working hearts of prevention and regressive groups, it was found that AP, LVSP, +dp/dtmax, -dp/dtmax, CF, and CI values of m-Nif and Nif groups increased higher than that of LVH group, but LVEDP and T was lower in m-Nif and Nif groups. It was concluded that m-Nif exhibits the similar effects like Nif in prevention and reversion of renovascular hypertensive LVH and improvement of hemodynamics.

Degradation of polyetherurethane by subcutaneous implantation into rats. I. Molecular weight change and surface morphology

Two kinds of polyetherurethane (PEU), U-3 and U-8, were coated in thin layers on an ethylene-vinylalcohol copolymer (EVAL) film 0.1 mm thick. U-3 is a nonsegmented PEU prepared from 4,4'-diisocyanatodiphenylmethane (MDI) and poly(tetramethylene oxide) of Mn = 1,000 (PTMO 1000), and U-8 is a segmented PEU prepared from MDI, PTMO 1000, and 1,4-butanediol. The coating thicknesses were 0.0068 and 0.022 mm for U-3 and U-8, respectively. These coated films were implanted subcutaneously into rats and retrieved after various weeks. The coatings on the retrieved samples were dissolved in tetrahydrofuran (THF), and the average molecular weight (MW) was determined by injecting the THF solution into a gel permeation chromatograph. In the case of U-3, MW increased after 2 weeks, then decreased over the implantation period. After 10 weeks, U-3 almost disappeared from the base film. In the case of U-8, MW reached the maximum at 4 weeks postimplantation then decreased gradually over the implantation period. The rate and degree of MW change were greater in U-3 than in U-8. Here, we argue that, in the early stage, low molecular weight PTMO/MDI oligomers leached out from the PEUs to the inflammatory exudate to increase MW, and in the later stage macrophage attachment/activation had a role in the degradation of PEUs. The surface morphologic changes observed by scanning electron microscopy are also discussed.

Effects of m-nifedipine on dihydropyridine binding sites in cardiac and cerebral cortex cell membranes from left ventricular hypertrophied rats

m-Nifedipine (m-Nif 20 mg.kg-1.d-1 ig for 9 wk) decreased left ventricular weight in the renovascular hypertensive rats (P < 0.01). Though not significantly affecting the density of dihydropyridines (DHP) receptor (Bmax), m-Nif administered whether for prevention (6 wk postclipping) or for regression (9 wk postclipping), markedly decreased the total number of DHP binding sites in hypertrophied left ventricle (LV). m-Nif also reduced the dissociation constant (Kd) of DHP binding sites in the membranes of LV and cerebral cortex from cardiac hypertrophied rats (P < 0.01). These effects of m-Nif were similar to those of nifedipine (Nif) in the same dosage. The results suggest that m-Nif can prevent and regress the LV hypertrophy resulted from renovascular hypertension and reduce the total number of DHP binding sites in the membranes of LV from cardiac hypertrophied rats.

Prevention of tissue calcification on bioprosthetic heart valve by using epoxy compounds: a study of calcification tests in vitro and in vivo

Calcification is the principal cause of the clinical failures of the bioprosthetic heart valves fabricated from glutaraldehyde pretreated porcine aortic valves or bovine pericardium. In this paper, we compared the calcification on various types of bovine pericardiums pretreated with two hydrophilic epoxy compounds adding GA post-treatment (EP 1 and EP 2), glutaraldehyde (GA)- and nontreated pericardium (Fresh), respectively, by in vitro and in vivo tests. Significant decrease of calcification was found by pretreatment with both epoxy compounds rather than with glutaraldehyde: 0.250 +/- 0.001 (Fresh), 0.276 +/- 0.058 (EP 1), 0.302 +/- 0.071 (EP 2), and 0.478 +/- 0.172 (GA) micrograms (Ca)/mg (dried tissue), respectively, after 20 days dipping in a simulating serum solution in vitro; 115.13 +/- 60.11 (Fresh), 129.84 +/- 51.08 (EP 1), 167.39 +/- 20.81 (EP 2), and 205.19 +/- 16.86 (GA) micrograms/mg, respectively, after 3 months subcutaneous implantation in rabbits. The in vitro method for evaluating calcification designed by us gave the similar order among four samples with that obtained by in vivo test. Because the bovine pericardium pretreated with the epoxy compounds adding GA post-treatment possesses the greater tenacity than that pretreated only with epoxy compounds or GA, meanwhile the calcification is also significantly decreased with this pretreatment, it may be expected that the bovine pericardium with this pretreatment will have the greater anticalcification and durability in dynamic stress.

Effect of pretreatment with epoxy compounds on the mechanical properties of bovine pericardial bioprosthetic materials

Early failures of bovine pericardial heart valves are due to leaflet perforation, tearing and calcification. Since glutaraldehyde fixation has been shown to produce marked changes in leaflet mechanics and has been linked to development of calcification, bovine pericardium fixed with the four hydrophilic epoxy formulations and their mechanical properties are studied in this paper. We measured the thicknesses, shrinkage temperatures, stress relaxations and stress-strain curves of bovine pericardiums after different treatments with (1) non-treatment (fresh), (2) glutaraldehyde (GA), (3) epoxy compounds followed by the posttreatment with GA (EP 1#, EP 2#), and (4) epoxy compounds (EP 3# and EP 4#). Results of this study showed that the hydrophilic epoxy compounds are good crosslinking agents. There are no significant differences of shrinkage temperature and ultimate tensile stress among all tissue samples pretreated with GA, EP 1# and EP 2#. However, the stress relaxations of tissue-samples pretreated with epoxy compounds followed by the posttreatment with GA (EP 1# and EP 2#) are significantly slower than that pretreated with GA, and the strains at fracture of EP 1# and EP 2# are also significantly larger than that of GA or epoxy compounds. These facts show that the bovine pericardium pretreated with the epoxy compound followed by the posttreatment with GA (EP 1# and EP 2#) possesses greater tenacity and potential durability in dynamic stress.

Haemocompatibility of polymer having phospholipid polar groups evaluated by monoclonal antibody method

The haemocompatibility of a polymer having the phospholipid polar group, poly(2-methacryloyloxyethyl phosphorylcholine (MPC)-co-n-butyl methacrylate(BMA)), was evaluated by a monoclonal antibody SZ-21 (directing specifically against the membrane glycoprotein complex IIIa of human platelet) radioimmunoassay method. The study showed that poly(MPC-co-BMA) possessed better haemocompatibility than segmented polyurethane (SPEU). Radioactivity of platelets adhered (counts per min/cm) on a polyethylene (PE) tube coated with poly(MPC-co-BMA) was 19.51 +/- 5.58, with albumin; 20.05 +/- 7.29, with SPEU having sulphonated group; 76.10 +/- 18.9, with SPEU; 287.0 +/- 95.0, PE treated by plasma irradiation; 2091 +/- 261, and original PE was 1772 +/- 116. The results were further certified by scanning electron microscopic observations.