The Perception of Depth and Form in Fine Arts, Video Games and Medicine.

Medical imaging technology has greatly improved over the last 40 years. A good example of this is the improved 3D reconstruction capabilities of CTs, which enable photorealistic reconstructions. This technological advancement has also taken place in the computer industry, and the development of modern graphics cards has fueled progress in video games. In art, many of the techniques used to improve three-dimensionality have been known for centuries. At first sight, these fields seem unrelated, but there is actually considerable confluence. This paper focuses on three areas: fine arts, video games and radiology. The art section illustrates different drawing techniques used to create three-dimensionality. The section on video games shows the development of video games from the 1980s to the present day. Finally, the medical imaging section focuses on the first 3D radiography reconstructions in the 1980s and the improvements to the present day. Contemporary video games and 3D reconstructions of CTs enable photorealistic impressions of 3D anatomical structures. An important factor is shadow casting and light, which has been known in fine arts for centuries. The effect on the observer of photorealistic 3D reconstructions in video games and in medical imaging can be largely explained by the knowledge of 3D techniques in drawings and paintings.

Antibiotic prophylaxis before dental procedures to prevent infective endocarditis: a systematic review.

PURPOSE: Infective endocarditis (IE) is a severe bacterial infection. As a measure of prevention, the administration of antibiotic prophylaxis (AP) prior to dental procedures was recommended in the past. However, between 2007 and 2009, guidelines for IE prophylaxis changed all around the word, limiting or supporting the complete cessation of AP. It remains unclear whether AP is effective or not against IE. METHODS: We conducted a systematic review whether the administration of AP in adults before any dental procedure, compared to the non-administration of such drugs, has an effect on the risk of developing IE. We searched for studies in the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE via OVID, and EMBASE. Two different authors filtered articles independently and data extraction was performed based on a pre-defined protocol. RESULTS: The only cohort study meeting our criteria included patients at high-risk of IE. Analysis of the extracted data showed a non-significant decrease in the risk of IE when high-risk patients take AP prior to invasive dental procedures (RR 0.39, p-value 0.11). We did not find other studies including patients at low or moderate risk of IE. Qualitative evaluation of the excluded articles reveals diversity of results and suggests that most of the state-of-the-art articles are underpowered. CONCLUSIONS: Evidence to support or discourage the use of AP prior to dental procedures as a prevention for IE is very low. New high-quality studies are needed, even though such studies would require big settings and might not be immediately feasible.

Accuracy of augmented reality-assisted vs template-guided apicoectomy - an ex vivo comparative study.

AIM: The aim of the present ex vivo study was to examine the accuracy of augmented reality-assisted apicoectomies (AR-A) versus template-guided apicoectomies (TG-A). MATERIALS AND METHODS: In total, 40 apicoectomies were performed in 10 cadaver pig mandibles. Every pig mandible underwent two AR-A and two TG-A in molar and premolar teeth. A crossed experimental design was applied. AR-A was performed using Microsoft HoloLens 2, and TG-A using SMOP software. Postoperative CBCT scans were superimposed with the presurgical planning data. The deviation between the virtually planned apicoectomy and the surgically performed apicoectomy was measured. The primary (angular deviation [degrees]) and secondary (depth deviation [mm]) outcome parameters were measured. RESULTS: Overall, 36 out of 40 apicoectomies could be included in the study. Regarding the primary outcome parameter (angular deviation), there was no significant difference between AR-A and TG-A. The mean values were 5.33 degrees (± 2.96 degrees) in the AR-A group, and 5.23 degrees (± 2.48 degrees) in the TG-A group. The secondary outcome parameter (depth deviation) showed no significant difference between the AR-A group of 0.27 mm (± 2.32 mm) and the TG-A group of 0.90 mm (± 1.84 mm). In this crossed experimental design, both techniques overshot the target depth in posterior sites, as opposed to not reaching the target depth in anterior sites (P < 0.001). CONCLUSION: Augmented reality (AR) technology has the potential to be introduced into apicoectomy surgery in case further development is implemented.

Preoperative visualization of the lingual nerve by 3D double-echo steady-state MRI in surgical third molar extraction treatment.

OBJECTIVES: To assess the lingual nerve (LN) visualization using a 3D double-echo steady-state MRI sequence (3D-DESS). MATERIALS AND METHODS: Three readers prospectively evaluated the LN for its continuous visibility in 3D-DESS MRI in 19 patients with an indication for removal of mandibular impacted third molars, using a 5-point scale (4 = excellent to 0 = none). Six LN anatomical intermediate points (IP) were selected and checked for their detectability by a 4-point scale (4 = yes to1 = no). Inter- and intra-rater agreement was evaluated using intraclass correlation coefficient and percentage of agreement. RESULTS: The average nerve continuity score was 3.3 ± 0.46. In 35% of the cases, the entire course was continuously visible. In 10%, the proximal and 60%, the distal part of the nerve was not continuously visible. Inter- and intra-reader agreement was good (ICC = 0.76, ICC = 0.75). The average detectability score of all IP was 3.7 ± 0.41. From IP1 to IP5, the detectability was excellent; meanwhile, IP6 had lower visibility. The inter- and intra-reader percentage of agreement was 77% and 87%. CONCLUSIONS: The 3D-DESS sequence allowed accurate and continuous visualization of the LN with high reproducibility in more than one-third of the patients. This could improve the preoperative clarification of the LN position and thereby reduce complications during dentoalveolar surgical interventions. CLINICAL RELEVANCE: 3D-DESS MRI might be beneficial in clinical scenarios where the second molar is elongated or presents a difficult rotational position while simultaneously having a close positional relationship to the third molar. Thereby, osteotomy performed more lingually, indicating extended lingual flap detachment may increase the risk of LN damage.

FDG-PET/CT for oral focus assessment in head and neck cancer patients.

OBJECTIVES: To compare oral and maxillo-mandibular inflammatory foci on standard oral radiographs (OPT, periapical radiograph) with available fluorine-18-labelled fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography (FDG-PET/CT) data and to discuss whether additional metabolic information derived from FDG-PET/CT can support oral care specialists when performing oral focus examinations. MATERIALS AND METHODS: Data from 23 patients with head and neck cancer who underwent FDG-PET/CT and panoramic and periapical radiography in close succession before first-line radiotherapy and/or chemotherapy were included in this exploratory retrospective study. Periapical lesions and marginal periodontal inflammation on FDG-PET/CT scans and standard oral radiographs were analysed and compared with regard to metabolic activity on FDG-PET/CT in comparison to recorded clinical symptoms and radiological scores. Additionally, inflammatory maxillo-mandibular pathologies were analysed using FDG-PET/CT. RESULTS: The maximum standardised uptake value (SUVmax) in FDG-avid marginal periodontal sites could not be conclusively associated with the radiologically recorded severity of marginal bone loss, but a potential positive correlation was identified. No association was found either between the metabolic activity of periapical lesions and their extent, as recorded on standard oral radiographs, or regarding clinical symptoms (percussion test). Most maxillo-mandibular pathologies did not show increased FDG uptake. CONCLUSIONS: FDG-PET/CT provided additional metabolic information that can help clinicians identify lesions with increased inflammatory activity. The incorporation of available oral FDG-PET/CT findings into the primary oral focus assessment may allow for more accurate oral focus treatment. CLINICAL RELEVANCE: FDG-PET/CT provides valuable metabolic information for oral care specialists. The detection of inflammatory oral processes using FDG-PET/CT facilitates treatment.

Diagnostic Accuracy of Cystic Lesions Using a Pre-Programmed Low-Dose and Standard-Dose Dental Cone-Beam Computed Tomography Protocol: An Ex Vivo Comparison Study.

BACKGROUND: This study aimed to analyze the diagnostic reliability of radiographic assessment of cystic lesions using a pre-set, manufacturer-specific, low-dose mode compared to a standard-dose dental cone-beam computed tomography (CBCT) imaging protocol. METHODS: Forty pig mandible models were prepared with cystic lesions and underwent both CBCT protocols on an Orthophos SL Unit (Dentsply-Sirona, Bensheim, Germany). Qualitative and quantitative analysis of CBCT data was performed by twelve investigators independently in SIDEXIS 4 (Dentsply-Sirona) using a trial-specific digital examination software tool. Thereby, the effect of the two dose types on overall detectability rate, the visibility on a scale of 1 (very low) to 10 (very high) and the difference between measured radiographic and actual lesion size was assessed. RESULTS: Low-dose CBCT imaging showed no significant differences considering detectability (78.8% vs. 81.6%) and visibility (9.16 vs. 9.19) of cystic lesions compared to the standard protocol. Both imaging protocols performed very similarly in lesion size assessment, with an apparent underestimation of the actual size. CONCLUSION: Low-dose protocols providing confidential diagnostic evaluation with an improved benefit-risk ratio according to the ALADA principle could become a promising alternative as a primary diagnostic tool as well as for radiological follow-up in the treatment of cystic lesions.

Toward Biofabrication of Resorbable Implants Consisting of a Calcium Phosphate Cement and Fibrin-A Characterization In Vitro and In Vivo.

Cleft alveolar bone defects can be treated potentially with tissue engineered bone grafts. Herein, we developed novel biphasic bone constructs consisting of two clinically certified materials, a calcium phosphate cement (CPC) and a fibrin gel that were biofabricated using 3D plotting. The fibrin gel was loaded with mesenchymal stromal cells (MSC) derived from bone marrow. Firstly, the degradation of fibrin as well as the behavior of cells in the biphasic system were evaluated in vitro. Fibrin degraded quickly in presence of MSC. Our results showed that the plotted CPC structure acted slightly stabilizing for the fibrin gel. However, with passing time and fibrin degradation, MSC migrated to the CPC surface. Thus, the fibrin gel could be identified as cell delivery system. A pilot study in vivo was conducted in artificial craniofacial defects in Lewis rats. Ongoing bone formation could be evidenced over 12 weeks but the biphasic constructs were not completely osseous integrated. Nevertheless, our results show that the combination of 3D plotted CPC constructs and fibrin as suitable cell delivery system enables the fabrication of novel regenerative implants for the treatment of alveolar bone defects.

A volumetric assessment and follow-up of a granuloma gravidarum in the anterior maxilla.

AIM: Granuloma gravidarum (GG) is a benign lesion of the soft tissue. The aim of this technical note is the volumetric assessment and follow-up 3D measurement of a GG in the anterior maxilla. MATERIALS AND METHODS: A 35-year-old female patient who was 7 months pregnant was referred due to a soft tissue tumor in the papilla of tooth 21. A biopsy verified a pyogenic granuloma gravidarum. Initial and consecutive volumeatric measurements were made with an intraoral scanner during the patient's pregnancy and until 16 months postpartum. RESULTS: The volumetric assessment showed a continuous growth of the tumor and a consecutive volume reduction 16 months postpartum. In comparison with the level of the papilla of the contralateral incisor, there was an almost complete remission at the last follow-up. CONCLUSION: Intraoral scans can serve for the volumetric assessment of soft tissue tumors of the alveolar crest. Image superimposition enables the quantification of changes in morphology. This supports clinical follow-ups and enables the quantification of clinical observations.

Peri-implantitis and its prevention.

This perspective article on peri-implantitis and its prevention was produced as a supplement to a 3-D, computer-animated film aiming at presenting key characteristics of peri-implant health, the build-up of a biofilm and the ensuing host-response resulting in peri-implant mucositis and, subsequently, peri-implantitis. Treatment concepts for peri-implantitis were briefly reviewed, and prevention of the condition was brought to attention as a priority in implant dentistry. The overview also highlighted the 2017 World Workshop on Classification of Periodontal and Peri-implant diseases and Conditions, in which new disease definitions and case definitions were presented for peri-implant health, peri-implant mucositis, and peri-implantitis.

Guided apicoectomy using a CAD/CAM drilling template.

AIM: Modern microsurgical techniques have increased the success rate of apicoectomy relative to that of traditional approaches. This case report introduces a novel workaround for guided apicoectomy using a patient-specific computer-aided design/computer-aided manufacturing (CAD/CAM) three-dimensional (3D)-printed template. MATERIALS AND METHODS: Apicoectomy was performed on the mesial root of tooth 36 using template-guided trephine drilling, followed by retrograde filling with mineral trioxide aggregate (MTA). Initially, a cone beam computed tomography (CBCT) scan and an intraoral surface scan were imported into the planning software. After superimposition, virtual planning was performed to determine the exact localization for root resection. Subsequently, a tooth-supported drilling template was designed and 3D printed. Endodontic microsurgical approaches, including root-end cavity preparation and root-end filling, completed the surgical treatment. RESULT: The apical resection was easily feasible. There were no postoperative complications. Radiological assessment after a 6-month period showed signs of reossification. CONCLUSION: Guided apicoectomy allowed precise root resection, suggesting that this technique may be advantageous in complex anatomical situations.

Cone Beam Computed Tomography Evaluation of the Artery in the Lateral Wall of the Maxillary Sinus: Retrospective Analysis of 602 Sinuses.

PURPOSE: This retrospective study evaluates the location of the arteries in the maxillary sinus, particularly in the middle portion, using cone beam computed tomography (CBCT) scans that can detect the lateral arteries with high reliability. METHODS: In this retrospective study, 2 experienced independent examiners evaluated 602 sinuses on CBCT scans. DISCUSSION: No significant correlation was found between the location of arteries and the patient's age, sex, or dentition. In 92.0% (P ≤ 0.001) of the sinuses, at least 1 arterial branch was detectable. CONCLUSION: Based on the CBCT scans, we found that a very high proportion of patients have the maxillary artery in their lateral sinus wall, which is important information for sinus augmentation or sinus surgery.

Oral manifestation of Langerhans cell histiocytosis: a case report.

BACKGROUND: Bone necrosis of the jaw is a serious condition with a broad differential diagnosis of pathologies such as cutaneous histiocytosis, bone metastases or malignant tumours. In addition to the most common cause, medication related osteonecrosis of the jaw (MRONJ), one must consider a number of other causes, such as histiocytosis. Langerhans cell histiocytosis (LCH) is a histiocytic disorder with a large spectrum of clinical manifestations and with possible involvement of a variety of organs. This case shows the importance of an early detection of this rare disease in order to prevent further spreading. Even if an initial diagnosis in the oral cavity is rare, dentists should be aware of this disease. CASE PRESENTATION: The presented case describes a patient who was referred for evaluation and treatment due to exposed bone and extensive osteolysis in the region of the upper and lower jaw. After biopsy and diagnosis of LCH, the patient was treated with systemic therapy, achieved remission and is disease free after a 2 year of follow up. CONCLUSIONS: This case report illustrates that when dealing with unclear osteolytic changes of the jawbone, Langerhans cell histiocytosis must be taken into consideration in the differential diagnosis and biopsy must be performed in case of suspicion.

Cell-to-cell communication in guided bone regeneration: molecular and cellular mechanisms.

This overview provides insights into the molecular and cellular mechanisms involved in guided bone regeneration, in particular focusing on aspects presented in the 3D movie, Cell-To-Cell Communication in Guided Bone Regeneration. The information presented here is based almost exclusively on genetic mouse models in which single genes can be deleted or overexpressed, even in a specific cell type. This information needs to be extrapolated to humans and related to aspects relevant to graft consolidation under the clinical parameters of guided bone regeneration. The overview follows the ground tenor of the Cell-To-Cell Communication series and focuses on aspects of cell-to-cell communication in bone regeneration and guided bone regeneration. Here, we discuss (1) the role of inflammation during bone regeneration, including (2) the importance of the fibrin matrix, and (3) the pleiotropic functions of macrophages. We highlight (4) the origin of bone-forming osteoblasts and bone-resorbing osteoclasts as well as (5) what causes a progenitor cell to mature into an effector cell. (6) We touch on the complex bone adaptation and maintenance after graft consolidation and (7) how osteocytes control this process. Finally, we speculate on (8) how barrier membranes and the augmentation material can modulate graft consolidation.

Cell-to-cell communication--periodontal regeneration.

BACKGROUND: Although regenerative treatment options are available, periodontal regeneration is still regarded as insufficient and unpredictable. AIM: This review article provides scientific background information on the animated 3D film Cell-to-Cell Communication - Periodontal Regeneration. RESULTS: Periodontal regeneration is understood as a recapitulation of embryonic mechanisms. Therefore, a thorough understanding of cellular and molecular mechanisms regulating normal tooth root development is imperative to improve existing and develop new periodontal regenerative therapies. However, compared to tooth crown and earlier stages of tooth development, much less is known about the development of the tooth root. The formation of root cementum is considered the critical element in periodontal regeneration. Therefore, much research in recent years has focused on the origin and differentiation of cementoblasts. Evidence is accumulating that the Hertwig's epithelial root sheath (HERS) has a pivotal role in root formation and cementogenesis. Traditionally, ectomesenchymal cells in the dental follicle were thought to differentiate into cementoblasts. According to an alternative theory, however, cementoblasts originate from the HERS. What happens when the periodontal attachment system is traumatically compromised? Minor mechanical insults to the periodontium may spontaneously heal, and the tissues can structurally and functionally be restored. But what happens to the periodontium in case of periodontitis, an infectious disease, after periodontal treatment? A non-regenerative treatment of periodontitis normally results in periodontal repair (i.e., the formation of a long junctional epithelium) rather than regeneration. Thus, a regenerative treatment is indicated to restore the original architecture and function of the periodontium. Guided tissue regeneration or enamel matrix proteins are such regenerative therapies, but further improvement is required. As remnants of HERS persist as epithelial cell rests of Malassez in the periodontal ligament, these epithelial cells are regarded as a stem cell niche that can give rise to new cementoblasts. Enamel matrix proteins and members of the transforming growth factor beta (TGF-ß) superfamily have been implicated in cementoblast differentiation. CONCLUSION: A better knowledge of cell-to-cell communication leading to cementoblast differentiation may be used to develop improved regenerative therapies to reconstitute periodontal tissues that were lost due to periodontitis.

Peri-implant infections of oral biofilm etiology.

Biofilms are complex microbial communities that grow on various surfaces in nature. The oral micobiota tend to form polymicrobial biofilms, particularly on the hard mineralized surfaces of teeth, which may impact on oral health and disease. They can cause inflammation of the adjacent tooth-supporting (periodontal) tissues, leading to destructive periodontal disease and tooth loss. The emergence of osseointegrated dental implants as a restorative treatment option for replacing missing teeth has also brought along new artificial surfaces within the oral cavity, on which oral bacteria can form biofilms. As in the case of natural teeth, biofilms on implant surfaces may also trigger infection and cause inflammatory destruction of the peri-implant tissue (i.e. peri-implantitis). While there are strong similarities in the composition of the mixed microbial flora between periodontal and peri-implant infections, there are also a few distinctive differences. The immunological events underlying the pathogenesis of peri-implant infections are qualitatively similar, yet more extensive, compared to periodontal infections, resulting in a faster progression of tissue destruction. This chapter summarizes the current knowledge on the microbiology and immunology of peri-implant infections, including findings from the peri-implant crevicular fluid, the inflammatory exudate of the peri-implant tissue. Moreover, it discusses the diagnosis and current approaches for the treatment of oral infections.

Inflammatory reaction - communication of cells.

This article presents scientific background information on the animated 3D film "Inflammatory Reactions - Communication of Cells" (Quintessence Publications, ISBN 978-1-85097-231-0). Gingivitis and periodontitis are understood as the result of a coordinated action of a few clearly identified cellular players who communicate with each other via cytokines. For didactic reasons, the course of a periodontal infection is described here in four phases: (1) bacterial biofilm formation and development of a host response in the marginal periodontium, (2) innate immune response leading to gingivitis, (3) role of the adaptive immune system in attachment loss and pocket formation, and (4) down-regulation of inflammation and periodontal regeneration and repair following biofilm removal. The control of the cells is discussed as a cytokine network, which can be modulated in pro- or anti-inflammatory direction depending on the control of the bacterial infection. Degradation of soft tissue structural proteins like collagen and proteoglycans by matrix metalloproteinases and degradation of hard tissue matrix by osteoclasts are explained as an interference of the immune system with the natural equilibrium of tissue remodeling. Five mechanisms of promotion of bone loss through the influence of the immune system are described. One example is bone resorption as a consequence of the shift of the RANKL/osteoprotegerin balance by soluble RANKL synthesized by CD4(+) Th 1 cells as well as the interference with the coupling of osteoclasts and osteoblasts through dedifferentiation of osteoblasts by TNFα. Finally, the signaling required for down-regulation of inflammatory reactions and the reasons for the incomplete regeneration after periodontal bone loss are discussed.

Coating with artificial matrices from collagen and sulfated hyaluronan influences the osseointegration of dental implants.

Dental implants are an established therapy for oral rehabilitation. High success rates are achieved in healthy bone, however, these rates decrease in compromised host bone. Coating of dental implants with components of the extracellular matrix is a promising approach to enhance osseointegration in compromised peri-implant bone. Dental titanium implants were coated with an artificial extracellular matrix (aECM) consisting of collagen type I and either one of two regioselectively low sulfated hyaluronan (sHA) derivatives (coll/sHA1Δ6s and coll/sHA1) and compared to commercial pure titanium implants (control). After extraction of the premolar teeth, 36 implants were inserted into the maxilla of 6 miniature pigs (6 implants per maxilla). The healing periods were 4 and 8 weeks, respectively. After animal sacrifice, the samples were evaluated histomorphologically and histomorphometrically. All surface states led to a sufficient implant osseointegration after 4 and 8 weeks. Inflammatory or foreign body reactions could not be observed. After 4 weeks of healing, implants coated with coll/sHA1Δ6s showed the highest bone implant contact (BIC; coll/sHA1Δ6s: 45.4%; coll/sHA1: 42.2%; control: 42.3%). After 8 weeks, a decrease of BIC could be observed for coll/sHA1Δ6s and controls (coll/sHA1Δ6s: 37.3%; control: 31.7 %). For implants coated with coll/sHA1, the bone implant contact increased (coll/sHA1: 50.8%). Statistically significant differences could not be observed. Within the limits of the current study, aECM coatings containing low sHA increase peri-implant bone formation around dental implants in maxillary bone compared to controls in the early healing period.