Comparing the Bone Healing After Cold Ablation Robot-Guided Er:YAG Laser Osteotomy and Piezoelectric Osteotomy-A Pilot Study in a Minipig Mandible.

BACKGROUND AND OBJECTIVE: To take major advantage of erbium-doped yttrium aluminium garnet (Er:YAG) lasers in osteotomy-like freedom of cutting geometries and high accuracy-the integration and miniaturization of the robot, laser, and navigation technology was tried and applied to minipigs. The investigators hypothesized laser osteotomy would render acceptable bone healing based on the intraoperative findings and postoperative cut surface analysis. STUDY DESIGN/MATERIALS AND METHODS: We designed and implemented a comparative bone-cutting surgery in the minipig mandible with a cold ablation robot-guided Er:YAG laser osteotome (CARLO) and a piezoelectric (PZE) osteotome. The sample was composed of different patterns of defects in the mandibles of six grown-up female Goettingen minipigs. The predictor variable was Er:YAG osteotomy and PZE osteotomy. The outcome variable was the cut surface characteristics and bone healing at 4 and 8 weeks postoperatively. Descriptive and qualitative comparison was executed. RESULTS: The sample was composed of four kinds of bone defects on both sides of the mandibles of six minipigs. We observed more bleeding during the operation, open-cut surfaces, and a faster healing pattern with the laser osteotomy. There was a possible association between the intraoperative findings, postoperative cut surface analysis, and the bone healing pattern. CONCLUSIONS: The results of this study suggest that characteristic open-cut surfaces could explain favorable bone healing after laser osteotomy. Future studies will focus on the quantification of the early healing characteristics after laser osteotomy, its diverse application, and the safety feature. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Quantitative Assessment of Point-of-Care 3D-Printed Patient-Specific Polyetheretherketone (PEEK) Cranial Implants.

Recent advancements in medical imaging, virtual surgical planning (VSP), and three-dimensional (3D) printing have potentially changed how today's craniomaxillofacial surgeons use patient information for customized treatments. Over the years, polyetheretherketone (PEEK) has emerged as the biomaterial of choice to reconstruct craniofacial defects. With advancements in additive manufacturing (AM) systems, prospects for the point-of-care (POC) 3D printing of PEEK patient-specific implants (PSIs) have emerged. Consequently, investigating the clinical reliability of POC-manufactured PEEK implants has become a necessary endeavor. Therefore, this paper aims to provide a quantitative assessment of POC-manufactured, 3D-printed PEEK PSIs for cranial reconstruction through characterization of the geometrical, morphological, and biomechanical aspects of the in-hospital 3D-printed PEEK cranial implants. The study results revealed that the printed customized cranial implants had high dimensional accuracy and repeatability, displaying clinically acceptable morphologic similarity concerning fit and contours continuity. From a biomechanical standpoint, it was noticed that the tested implants had variable peak load values with discrete fracture patterns and failed at a mean (SD) peak load of 798.38 ± 211.45 N. In conclusion, the results of this preclinical study are in line with cranial implant expectations; however, specific attributes have scope for further improvements.

A comparative investigation of bone surface after cutting with mechanical tools and Er:YAG laser.

BACKGROUND AND OBJECTIVES: Despite of the long history of medical application, laser ablation of bone tissue became successful only recently. Laser bone cutting is proven to have higher accuracy and to increase bone healing compared to conventional mechanical bone cutting. But the reason of subsequent better healing is not biologically explained yet. In this study we present our experience with an integrated miniaturized laser system mounted on a surgical lightweight robotic arm. STUDY DESIGN/MATERIALS AND METHODS: An Erbium-doped Yttrium Aluminium Garnet (Er:YAG) laser and a piezoelectric (PZE) osteotome were used for comparison. In six grown up female Göttingen minipigs, comparative surgical interventions were done on the edentulous mandibular ridge. Our laser system was used to create different shapes of bone defects on the left side of the mandible. On the contralateral side, similar bone defects were created by PZE osteotome. Small bone samples were harvested to compare the immediate post-operative cut surface. RESULTS: The analysis of the cut surface of the laser osteotomy and conventional mechanical osteotomy revealed an essential difference. The scanning electron microscopy (SEM) analysis showed biologically open cut surfaces from the laser osteotomy. The samples from PZE osteotomy showed a flattened tissue structure over the cut surface, resembling the "smear layer" from tooth preparation. CONCLUSIONS: We concluded that our new finding with the mechanical osteotomy suggests a biological explanation to the expected difference in subsequent bone healing. Our hypothesis is that the difference of surface characteristic yields to different bleeding pattern and subsequently results in different bone healing. The analyses of bone healing will support our hypothesis.

How much dentists are ethically concerned about overtreatment; a vignette-based survey in Switzerland.

BACKGROUND: Overtreatment (or unnecessary treatment) is when medical or dental services are provided with a higher volume or cost than is appropriate. This study aimed to investigate how a group of dentists in Switzerland, a wealthy country known to have high standards of healthcare including dentistry, evaluated the meaning of unnecessary treatments from an ethical perspective and, assessed the expected frequency of different possible behaviors among their peers. METHODS: A vignette describing a situation that is susceptible for overtreatment of a patient was presented to a group of dentists. The vignette was followed by five options. A questionnaire including the vignette was posted to 2482 dentists in the German-speaking areas of Switzerland. The respondents were asked to rate each option according to their estimation about its prevalence and their judgment about the degree to which the behavior is ethically sound. RESULTS: 732 completed questionnaires were returned. According to the responses, the most ethical and the most unethical options are considered to be the most and the least prevalent behaviors among dentists practicing in Switzerland, respectively. CONCLUSIONS: Suggesting unnecessary treatments to patients seems to be an ethically unacceptable conduct in the eyes of a sample of dentists in Switzerland. Although the respondents believed their colleagues were very likely to behave in an ethical way in response to a situation that is susceptible to overtreatment, they still seemed to be concerned about the prevalence of unethical behaviors in this regard.

"Anatomical simulation" of the biomechanical behavior of the human mandible.

INTRODUCTION: The load-carrying behavior of the human mandible can be described using finite element simulation, enabling investigations about physiological and pathological skeletal adaption. "Anatomical simulation" implies a stepwise approximation towards the anatomical reality. METHOD: The project is structured in three steps. In Step 1, the preprocessing, the simulation model is provided. Step 2 is the numerical computation. Step 3 is dedicated to the interpretation of the results. The requirements of the preprocessing are: a) realization of the organ's individual anatomy, namely its outer shape; b) the tissue's elastic properties, thus its inner consistency; and c) the organ's mechanical loads. For physiological mandibular loading, these are due to muscles, temporomandibular joints, and tooth forces. Meanwhile, the reconstruction of the macroscopic anatomy from computed tomography data is standard. The periodontal ligament is inserted ex post using an approach developed by the authors. The bone is modeled anisotropically and inhomogeneously. By the visualization of the individual fiber course, the muscular force vectors are realized. The mandibular condyle is freely mobile in a kind of simplified joint capsule. For the realization of bite forces, several approaches are available. RESULTS: An extendible software tool is provided, enabling the user - by variable input of muscle and bite forces - to examine the individual patient's biomechanics, eg, the influence of the periodontal ligament, the condition of the temporomandibular joints, atrophic processes, or the biomechanical situation of dental implants. DISCUSSION: By stepwise approximation towards the anatomical reality, the mandibular simulation will be advanced to a valuable tool for diagnosis and prognosis.

A simple, effective, universal, and reusable osteotomy tool for jaw reconstructions with microvascular fibula transplants.

BACKGROUND: Precise, expensive individual saw guides are used with increasing frequency for the reconstruction of mandibular defects with fibular grafts. In this report, an alternative is presented - the Multiuse Cutting Jig (MUC-Jig, proprietary development). It is reusable, suitable for all patients, requires simple planning based on conventional CT imaging, and is more economical. METHODS: To investigate its precision, we conducted a nonblinded experimental study, with ten participating craniomaxillofacial surgeons. Osteotomies of four different fibula segments were carried out at the same angulation, with groups defined according to the proximal and distal fixed angulation: 45°, 30°, 15°, or 0°. The sagittal cut was performed proximally, with the coronal cut performed distally. The resulting 40 segments (n = 40) were analyzed with their Tx length (primary endpoint) and osteotomy angles, and compared to the original planning. RESULTS: The mean (SD) relative deviation of all grafts from the original planning was -0.08 mm (1.12) in length and -0.71° (3.15) for the angle. Only 45° (-2.04 ±â€¯3.71°) and 30° (-1.07 ±â€¯2.52°) cuts differed significantly (p < 0.05) from smaller angle grafts. The mean (SD) absolute deviation was 0.81 mm (0.27) in length and 2.13° (0.93) in graft angles. For individual transplants, 45° cuts (1.28 ±â€¯1.03 mm) differed significantly (p < 0.005) from others. We observed no differences in relative length or absolute angle deviation. CONCLUSIONS: The MUC-Jig is precise and cost-effective for osteotomies with medium angles and smooth reconstructions of template-guided procedures.

Comparison of the Visibility of Fetal Tooth Buds on 1.5 and 3 Tesla MRI.

Dental anomalies coincide with genetic disorders, and prenatal identification may contribute to a more accurate diagnosis. The aim of this study was to assess whether fetal Magnet Resonance Imaging (MRI) is suitable to visualize and investigate intrauterine dental development in the upper jaw, and to compare the quality of visibility of tooth buds between 1.5 Tesla (T) and 3T images. MR images of fetuses Gestational Week (GW) 26.71 ± 4.97 from 286 pregnant women with diagnoses unrelated to dental anomalies were assessed by three raters. We compared the visibility between groups and field strengths in five gestational age groups, using chi square and Fisher's exact tests. All ten primary tooth buds were identifiable in 5.4% at GW 18-21, in 75.5% at GW 26-29, and in 90.6% at GW 34+. Before GW 30, more tooth buds were identifiable on 3T images than on 1.5T images. Statistical significance was only reached for identification of incisors (p = 0.047). Therefore, 1.5T and 3T images are viable to visualize tooth buds, particularly after GW 25, and their analysis may serve as diagnostic criterion. MRI tooth bud data might have an impact on various fields of research, such as the maldevelopment of teeth and their causes. Analyzing tooth buds as an additional diagnostic criterion is not time consuming, and could lead to an improvement of syndrome diagnosis.

Evaluation of the Dimensional Accuracy of 3D-Printed Anatomical Mandibular Models Using FFF, SLA, SLS, MJ, and BJ Printing Technology.

With the rapid progression of additive manufacturing and the emergence of new 3D printing technologies, accuracy assessment is mostly being performed on isosymmetric test bodies. However, the accuracy of anatomic models can vary. The dimensional accuracy of root mean square values in terms of trueness and precision of 50 mandible replicas, printed with five common printing technologies, were evaluated. The highest trueness was found for the selective laser sintering printer (0.11 ± 0.016 mm), followed by a binder jetting printer (0.14 ± 0.02 mm), and a fused filament fabrication printer (0.16 ± 0.009 mm). However, highest precision was identified for the fused filament fabrication printer (0.05 ± 0.005 mm) whereas other printers had marginally lower values. Despite the statistically significance (p < 0.001), these differences can be considered clinically insignificant. These findings demonstrate that all 3D printing technologies create models with satisfactory dimensional accuracy for surgical use. Since satisfactory results in terms of accuracy can be reached with most technologies, the choice should be more strongly based on the printing materials, the intended use, and the overall budget. The simplest printing technology (fused filament fabrication) always scored high and thus is a reliable choice for most purposes.

Bruxism, myoarthropathy and psychosomatics / Bruxismus, Myoarthropathie und Psychosomatik

Bruxism and myoarthrophathy lead to a complex set of burdens that can involve both medical and psychological aspects. Muscular tension due to stress affects these burdens and leads to chronic pain. Using a stress model, it was explained how the individual processing of stress leads to varying negative effects on oral health and jaw function. Through a short survey, it is possible for the dentist to assess the extent of the chronic pain and the associated psychosocial burdens, and, when necessary, encourage the patient to undertake psychological guidance. By learning relaxation techniques and pain coping mechanisms, the pain can be reduced. In order to achieve a long lasting successful treatment, one must consider both medical and psychosomatic aspects.

Performing partial mandibular resection, fibula free flap reconstruction and midfacial osteotomies with a cold ablation and robot-guided Er:YAG laser osteotome (CARLO®) - A study on applicability and effectiveness in human cadavers.

OBJECTIVE: Aim of the study was to prove the safety, accuracy characteristics of contact-free laser osteotomy executed with the cold ablation and robot-guided Er:YAG laser osteotome in a human cadaver test. MATERIAL AND METHODS: On six human cadavers mandible resections with a swallowtail like pattern were performed with the laser system on each side. The defects were reconstructed with a fibula graft of identical design and enlarged by 0.2 units. Mandibles and fibulas width as well surgery times were recorded. Additionally a Le Fort I and median mandible split were done. Macroscopically, the bone margins were examined for necrosis. RESULTS: Laser osteotomies of the mandible up to a depth of 23 mm were possible without any thermal damage. Repeatability and precision of the system could be easily assessed. With the navigation system precise control of localization was achievable. Mean surgery time for the mandible resection was 13.32 min and for the fibula osteotomy 12.38 min. CONCLUSION: The simply transmission of a cold ablation and robot-guided laser osteotome in an operation room identical environment for surgical interventions could be demonstrated. Precise osteotomy patterns with freedom in the design and carbonisation-free cut surfaces have been shown.

Accuracy of soft tissue prediction in surgery-first treatment concept in orthognathic surgery: A prospective study.

PURPOSE: The purpose of this study was to provide a quantitative accuracy assessment of soft tissue predictions generated by a computer-aided maxillofacial planning system in patients undergoing orthognathic surgery following the "surgery-first" treatment. MATERIALS AND METHODS: For this study, we looked at 16 patients with open bite dentofacial-dysmorphosis who underwent orthognathic surgery. Surgeries were planned using conventional sketches and the newly developed computer-assisted SOTIRIOS planning software (developed by the authors). Validation procedures were performed in the following steps: (1) Standardized registration of the pre- and postoperative CT volumes; (2) Automated adjustment of the bone-related preoperative planning to the actual postoperative bony displacement; (3) Simulation of soft tissue changes according to the definitive bony movements; and (4) Calculation of soft tissue differences between the predicted and the actual 6-month postoperative results by distance mapping. RESULTS: The program produced a clinically satisfactory 3D soft tissue prediction, with a mean error of 1.46 mm ± 1.53 mm. The program was suitable for use in virtual surgical planning without technical assistance. CONCLUSION: This study shows that the program is quite accurate, enabling the surgeon to predict the outcome of the soft tissue. This has the potential to promote the routine application of the surgery-first approach in patients suffering from open bite.

A worldwide comparison of the management of surgical treatment of advanced oral cancer.

INTRODUCTION: Microvascular surgery following tumor resection has become an important field of oral and maxillofacial surgery (OMFS). Following the results from management of T1/T2 floor-of-mouth and tongue squamous cell carcinoma (SCC) in German-speaking countries, Europe, and worldwide, this paper presents specific concepts for the management of resection and reconstruction of T3/T4 SCC of the maxillary and mandibular alveolar process and tongue. METHODS: The DÖSAK questionnaire was distributed in three different phases to a growing number of maxillofacial units worldwide. Within this survey, clinical patient settings were presented to participants and center-specific treatment strategies were evaluated. RESULTS: A total of 188 OMFS units from 36 different countries documented their treatment strategies for T3/T4 maxillary and mandibular alveolar process and tongue SCC. The extent of surgical resections and subsequent reconstructions is more consistent than with T1/T2 tumors, although the controversy surrounding continuity resections and mandible-sparing procedures remains. For continuity resection of the mandible the fibula free flap is the most frequently used bone replacement, whereas maxilla reconstruction concepts are less consistent, ranging from locoregional coverage concepts and different microvascular reconstruction options to treatment via obturator prosthesis. CONCLUSION: Results from treatment strategies for T3/T4 tumors underline the limited evidence for the appropriate amount of resection and subsequent reconstruction process, especially in cases involving the mandible. Prospective randomized trials will be necessary in the long term to establish valid treatment guidelines.

Er:YAG laser osteotomy based on refined computer-assisted presurgical planning: first clinical experience in oral surgery.

OBJECTIVE: This case report was aimed at primary clinical experience concerning surgical extraction of a displaced tooth with the help of the Er:YAG laser based on refined computer-assisted presurgical planning. METHODS: The case refers to the extraction of a displaced maxillary canine in a female patient. For the osteotomy, a pulsed Er:YAG laser was applied with pulse energy of 500 mJ, pulse duration of 250 microsec and pulse frequency of 12 Hz. The fiber tip (1000 microm) was kept with a 1-2 mm distance to the bone surface. Refined presurgical computer-assisted planning was performed with regard to minimization of bone loss, especially for the sake of preservation of the alveolar ridge. Based on a detailed three-dimensional (3D) reconstruction of the patient's anatomy, dynamical simulations of a buccal and a palatinal variant of access osteotomy were provided. Additionally, a volumetric profile of bone tissue quality based on Hounsfield values was generated. RESULTS: By means of the 3D reconstruction and the tissue quality profile, both bone thickness and quality was evaluated as superior in the palatinal rather than in the vestibular part. Therefore, a classical buccal access window was chosen. The laser osteotomy allowed an exact cut geometry without any thermal damage and merely minimal bone loss. CONCLUSION: The enhanced possibilities by laser osteotomy allowed for full exploitation of presurgical planning. As regards the actual case, computer-assisted planning was of benefit for an appropriate choice of access osteotomy by enabling evaluation of the consistency of the bony structures.

[Early detection and prevention of oral precancer. An enquiry among dentists in Switzerland]. / Früherkennung und Prävention von Präkanzerosen der Mundhöhle. Eine Umfrage unter Zahnärzten in der Schweiz.

Squamous cell carcinoma ranks eighth among the most common tumors worldwide. In many cases, these tumors develop from a preliminary phase (precancerosis). For different reasons, these preinitial carcinomas are recognised too late or not at all. The aim of this study was to find out about the dentists' state of knowledge, their management of these tumors and their readiness for a prevention campaign among Swiss dentists. 800 questionnaires were mailed or handed out to dentists nationwide. 22% of the questionnaires were returned. 64% of the dentists stated to be highly motivated for further education and 81% were willing to participate in a prevention campaign. 94% of the dentists examine the oral mucosa inclusive the (palatine) tonsil bed at least once a year, but only 15% of the participating dentists discuss the risk factors like alcohol or tobacco consumption with their patients. The most common factors which inhibit prevention in daily routine are the patients' refusal, a lack of education in that field, absence of information flyers and lack of time. A primary and secondary prevention program would be preferable to achieve a decrease in the incidence rate of squamous cell carcinoma.

[The Er:YAG laser in dentoalveolar surgery]. / Der Er:YAG-Laser in der dentoalveolären Knochenchirurgie.

In contrast to many currently employed osteotomy techniques like saws or drills the use of short-pulsed laser light offers the possibility of non-contact and vibration-free bone cutting. With a wavelength of 2.94 microm the Er:YAG laser displays a consummate absorption in water and thus is particularly suitable for bone ablation. To examine the benefits of laser osteotomy in oral surgery a short-pulsed Er:YAG laser was used for different surgical procedures in 30 patients. Preliminary clinical findings revealed satisfactory cut efficiency and no carbonisation. No serious complications were encountered in the postoperative wound healing process. However, the surgical procedures were time-consuming.

A worldwide comparison of the management of T1 and T2 anterior floor of the mouth and tongue squamous cell carcinoma - Extent of surgical resection and reconstructive measures.

INTRODUCTION: Microvascular surgery following tumor resection has become an important field of oral maxillofacial surgery (OMFS). Following the results on general aspects of current reconstructive practice in German-speaking countries, Europe and worldwide, this paper presents specific concepts for the management of resection and reconstruction of T1/T2 squamous cell carcinoma (SCC) of the anterior floor of the mouth and tongue. METHODS: The DOESAK questionnaire was distributed in three different phases to a growing number of maxillofacial units worldwide. Within this survey, clinical patient settings were presented to participants and center-specific treatment strategies were evaluated. RESULTS: A total of 188 OMFS units from 36 different countries documented their treatment strategies for T1/T2 anterior floor of the mouth squamous cell carcinoma and tongue carcinoma. For floor of mouth carcinoma close to the mandible, a wide variety of concepts are presented: subperiosteal removal of the tumor versus continuity resection of the mandible and reconstruction ranging from locoregional closure to microvascular bony reconstruction. For T2 tongue carcinoma, concepts are more uniform. CONCLUSION: These results demonstrate the lack of evidence and the controversy of different guidelines for the extent of safety margins and underline the crucial need of global prospective randomized trials on this topic to finally obtain evidence for a common guideline based on a strong community of OMFS units.

[Soft tissue surgery with the diode laser--theoretical and clinical aspects]. / Weichteilchirurgie mit dem Diodenlaser--theoretische und klinische Aspekte.

Currently laser light of different wavelengths is used for all kinds of surgical procedures in oral and maxillofacial surgery. In this regard especially the diode laser is mainly used, because of its excellent effects on oral soft tissues. On the basis of various oral soft tissue lesions in 40 patients the benefits of the diode laser in daily practice are demonstrated. Intraoperative and postoperative clinical findings were excellent due to the sufficient cutting abilities, the good coagulation effect and the extremely small zone of thermal necrosis to surrounding tissues. By this the diode laser has proven as an alternative solution to conventional electrosurgery and scalpel. The precise treatment in the contact application mode, which allowed an easier and more controlled guidance of the laser beam, was another advantage of the fiber-assisted laser system. In conclusion the results show that the diode laser is a useful instrument in oral soft tissue surgery.

Three-dimensional fetal cephalometry: an evaluation of the reliability of cephalometric measurements based on three-dimensional CT reconstructions and on dry skulls of sheep fetuses.

AIM: To develop a 3D CT cephalometric analysis for maxillary growth evaluation of sheep fetuses operated in utero, and to evaluate the reliability of this analysis by comparing it with a direct cephalometric analysis on dry skulls. MATERIAL AND METHODS: Five skulls of operated sheep fetuses were used, which after preparation were CT scanned and a 3D reconstruction was performed. A cephalometric analysis was performed directly on the dry skulls as well as on the reconstructed 3D CT images. In total, 56 linear distances were measured. In order to access the error of the method, the procedure was repeated after a 2 week interval. RESULTS: The comparison between the direct cephalometric and the 3D CT analysis revealed that only 5 variables were significantly different. The evaluation of the error of method revealed that 7 variables of the direct cephalometric analysis and none of the 3D CT analysis differed significantly. CONCLUSIONS: According to the results of this study, it can be concluded that a cephalometric analysis on 3D CT reconstructed images of the skulls includes fewer identification errors and seems to be an accurate and reliable method that could be regarded at least as equivalent to conventional cephalometry.

Compared to controls, patients with ruptured aneurysm and surgical intervention show increase in symptoms of depression and lower cognitive performance, but their objective sleep is not affected.

OBJECTIVES: Patients with aneurysmal subarachnoid haemorrhage (aSAH) have impaired sleep and cognitive performance together with more difficulties in social and everyday life. Hypocortisolism has also been reported. However, a study assessing all dimensions between aSAH severity, objective and subjective sleep, cortisol secretion, cognitive performance and social and everyday life has not so far been performed. The aim of the present study was therefore two-fold: (1) to assess, in a sample of patients with aSAH, objective and subjective sleep, cognitive functioning, social skills and cortisol secretion concurrently, and (2) to compare patients on these variables with a control group. METHODS: Twenty-one patients (17 females; mean age: 58.80 years) with ruptured aneurysm and surgical intervention and 21 (14 females; mean age: 58.90 years) age- and gender-matched controls took part in the study. Assessments covered objective sleep-EGG recordings, subjective sleep, salivary cortisol analysis, and psychological functioning including memory performance, mood, and emotion recognition. RESULTS: Compared to healthy controls, patients had lower scores for verbal memory performance and emotion recognition; they also reported more marked depressive symptoms and complained of poor sleep. However, no differences were found for objective sleep or cortisol secretion. Subjective and objective sleep, cortisol secretion and psychological functioning were unrelated. CONCLUSIONS: Findings indicate that patients with aSAH face psychological rather than physiological issues.