Can computer-guided surgery help orthodontics in miniscrew insertion and corticotomies? A narrative review.

Orthodontics has considerably increased the use of technology combined with surgery as a tool to improve dental movements in terms of predictability, acceleration of movement, and fewer side effects. To achieve these goals miniscrews and corticotomy were introduced. The digital workflow permits an increase in the accuracy of surgical and orthodontic setups. The tool that transfers the information is the CAD/CAM (Computer-Aided Design/ Computer-Aided Manufacturing) template. The aim of this review is to illustrate the use of computer-guided surgery in orthodontics regarding miniscrews and piezocision. The search strategy was a combination of Medical Subject Headings (Mesh) and free text words for PubMed. A total of 27 articles were included in this review: 16 concerned miniscrews and 11 concerned corticotomy. The current need for faster treatments, the improved systems of anchorage, and the evolution of imaging technologies require operators to be knowledgeable of the digital workflow. CAD/CAM templates allow greater precision and predictability of miniscrew insertion even if in the hands of less experienced clinicians and permit a better orientation and depth of the cortical incision. In conclusion, digital planning makes surgery faster and easier and allows for the identification and correction of any potential problem before the procedure.

Accuracy Of Imaging Software for 3d Rendering of Tooth Structures, Usable in Clinical Settings.

AIM: The aim of this study was to evaluate the segmentation accuracy of dentition testing four free-source semi-automatic software. MATERIALS AND METHODS: A total of 20 cone-beam computed tomography (CBCT) were selected to perform semi-automatic segmentation of maxillary and mandibular dentition. The software tested were Invesalius, ITK-Snap, 3D Slicer and Seg3D. Each tooth model was also manually segmented (Mimics software) and set as the gold standard (GS) reference of the investigation. A specific 3D imaging technology was used to perform the superimposition between the teeth models obtained with semi-automatic software and the GS model, and to perform the surface-to-surface matching analysis. The accuracy of semi-automatic segmentation was evaluated calculating the volumetric mean differences (mean bias and limits of agreement) and the percentage of matching of the tooth models compared to the manual segmentation (GS). Qualitative assessments were performed using color-coded maps. All data were statistically analysed to perform software comparisons. RESULT: Statistically significant differences were found in the volumetric and matching percentage data (p < 0,05). Invesalius was the most accurate software for 3D rendering of the dentition with a volumetric bias (Mimics) ranging from 4,59 mm3 to 85,79 mm3; instead, ITK-SNAP showed the higher volumetric bias, ranging from 30,22 mm3 to 319,83 mm3. The dis-matched area was mainly located at the radicular region of the teeth. Volumetric data showed excellent inter-software reliability with coefficient values ranging from 0,951 to 0,997. CONCLUSIO: Different semi-automatic software algorithms could generate different patterns of inaccuracy error in the segmentation of teeth.

Factors affecting duration of post-surgical orthodontics in the Surgery First/Early Approach: A retrospective study.

BACKGROUND: Surgery First Approach (SFA) and Surgery Early (SE) are considered promising alternatives, compared to the conventional three-stages orthodontic-surgical approach, for treatment of dento-maxillofacial deformities. However, many features need further study, like the role of the orthodontist. Aim of the study was to analyse the clinical characteristics of patients who underwent SFA and SE, and if differences in duration of orthodontics could be influenced by clinical features. METHODS: A retrospective research was performed on patients who met the inclusion criteria for SFA (31) and SE (12), of the total of patients affected by dento-facial deformities in our Unit (191) in the period 2012-2017. After collection of clinical data, duration of orthodontics, age, pre-treatment PAR Index, ANB angle, amount of the curve of Spee were compared. A regression analysis evaluated if these clinical parameters, together with type of bracket and type of intervention, could influence the duration of post-surgical orthodontics. RESULTS: All patients who performed the SFA/SE were affected by class III, II and active Unilateral Condylar Hyperplasia (22% of total population). Pre-treatment mean differences of age (p = 0.0518), PAR Index (p = 0.0916), curve of Spee (p = 0.1006) between groups were not statistically significant. A statically significant difference was found for the overall duration of therapy, for the significant shorter duration of pre-surgical orthodontics, while the difference of post-surgical orthodontics duration was not significant (p = 0.4753). Type of bracket (rho=-0.19039, p = 0.266) and intervention performed (rho=-0.11522, p = 0.5034) were not correlated with duration of post-surgical orthodontics, as well as pre-treatment PAR Index, ANB angle and depth of the curve of Spee. CONCLUSIONS: Surgery First/Early Approach is a therapeutic choice that could be performed only in patients affected by specific malocclusions and who exactly meet indications. Protocol and post-surgical occlusal stability are factors that should influence the duration of therapy more than clinical characteristics.

Smile esthetic: comparison of perception amongst orthodontists, dental students, orthodontic patients and surgical orthodontic patients

Most patients require orthodontic treatment to improve the esthetics of their smile. Orthodontists must consider how some parameters of mini-esthetics can influence the patient's esthetic perception. Methods: A photograph of the smile of a young female was taken and some modifications were made to the buccal corridor, gingival exposure, smile arc and midline position to assess the influence of these variables on smile attractiveness. Two hundred examiners were selected from four groups: orthodontists (O), dental students (DS), orthodontic patients (OP) and surgical-orthodontic patients (SOP). Each examiner was asked to complete the questionnaire with an approval rating from 1 to 10. Significant level was set at P ≤ 0.05. Results: Only orthodontists considered buccal corridors of 4mm and midline deviation of 1mm as non-esthetic; all other examiners considered gingival exposures ≥3 mm and midline angulation as non-esthetic. All examiners assigned higher satisfaction values to the photo with the concordant smile arc and defined as non-esthetic the covered smile and the reverse smile arc. Patients perceived as non-esthetic only midline deviations of 4mm. The surgical orthodontic patients assigned lower values to the photos and showed greater attention to evaluating the esthetics of the smile than the orthodontic patients. Conclusion: Smile arc, gingival exposure and midline angulation influence smile esthetics; the role of buccal corridors and midline deviation is dependent on the type of examiner

Assessment of maxillary canting on cone beam computed tomography and digital models: A retrospective study and proposal of a method.

OBJECTIVES: The mounting of the plaster casts on articulator procedure is routinely performed in orthognathic surgery to assess canting of the maxillary occlusal plane, but the currently used protocols and reference plane could be source of errors which affect reliability. Nowadays the assessment of canting of the maxillary occlusal plane could be also performed with an entirely digital protocol. Aim of the study was to propose a method to evaluate canting in patients affected by Unilateral Condylar Hyperplasia, comparing the measurements performed on digital models matched on CBCT with those made on traditional articulator. MATERIALS AND METHODS: A retrospective cross-sectional study was designed on 20 patients affected by vertical Unilateral Condylar Hyperplasia treated in the Units of Orthodontics and Maxillo-Facial Surgery. The canting of the maxillary occlusal plane was measured on plaster casts mounted on the conventional articulator and the measures were compared with those made on digital models matched on CBCT, according the protocol developed in our Unit. Molar, canine and basal difference were measured. To compare the two protocols and to test the agreement, we performed descriptive statistics, comparison between means and Bland Altman analysis. P value was set at 0.05. RESULTS: Statistic comparison demonstrated agreement between measurements performed with the digital protocol and conventional physical method. CONCLUSION: Measurements of canting with digital protocol are comparable to the physical standard method. A total digital protocol allows faster availability and storage of patient's data and better communication between orthodontist and maxillo-facial surgeon, especially in patients affected by three-dimensional malocclusions.

Periodontal evaluation of palatally impacted maxillary canines treated by closed approach with ultrasonic surgery and orthodontic treatment: a retrospective pilot study.

Aim of this study is the evaluation of the periodontal status of impacted canines treated by closed approach with ultrasonic surgery and orthodontic treatment compared with contralateral spontaneously erupted teeth. The periodontal conditions of the teeth adjacent to the canines (lateral incisors and first premolar) were also considered. 17 patients (9 females and 8 males; mean age: 15.2 years) with unilateral palatal impaction of maxillary canine were selected. All patients were treated by closed-flap surgery with ultrasonic instruments. Periodontal status was evaluated by assessing probing depth (PD), gingival recession and width of keratinized tissue (KT) 4.6 months after the end of the orthodontic treatment, on average. Test group was composed by impacted elements and adjacent teeth and control group by contralateral spontaneously erupted canines and adjacent teeth. Student's t-test was used to compare test and control group values of PD and width of KT. Significance threshold for Student's t-test was set at p < 0.05. The average probing depth values show no significant clinical differences between the test and control groups. Probing depths recorded at the mesiovestibular and distopalatal sides of the impacted canine were statistically significant compared to the control elements (p < 0.05). No gingival recession was detected on the treated canines. The measurement of KT did not differ significantly between the test and the control groups. In conclusion, the ultrasonic surgery for disinclusion associated with a closed approach and orthodontic traction allows the alignment of an impacted palatal canine without damaging the periodontium.

Thermographic Control of Pediatric Dental Patients During the SARS-CoV-2 Pandemics Using Smartphones

Abstract Objective: To evaluate the reliability of infrared (IR) thermal camera connected to smartphones, already used in medicine for diagnostic purposes, as an easy tool for access screening to pediatric dentistry services. Material and Methods: After the preventive telephone triage, thirty orthodontic patients (7-13 years) underwent temperature measurement in the office with two no-contact IR devices: forehead digital thermometer and thermal-camera connected to a smartphone (reference areas: forehead, inner canthi, ears). Measurements were compared and differences were statistically investigated with T student's test (p<0.01). Results: Forehead digital thermometer temperatures were superimposable to those recorded in ear areas and inner canthi with the thermal camera connected to a smartphone. Differences were not statistically significant even in comparison between the sexes. Forehead temperature values detected with a thermal camera are lower than those detected with a digital forehead thermometer. Conclusion: Thermal camera on a smartphone could be reliable in measuring body temperature. Mobile thermographic values of ears and inner canthi areas can be used as an alternative to forehead digital thermometer measurements. Further applications in pediatric dentistry of thermography on smartphones should be examined.

Management of Medication-Related Osteonecrosis of the Jaw (MRONJ) Using Leukocyte- and Platelet-Rich Fibrin (L-PRF) and Photobiomodulation: A Retrospective Study.

BACKGROUND: The aim of this study was to compare retrospectively the effect of three different treatment protocols on the healing outcome in patients with established medication-related osteonecrosis of the jaw (MRONJ). METHODS: A total of 34 MRONJ patients were recruited from the Department database and were divided according to the treatment protocols in a study group (G1) and two control groups (G2 and G3). G1 was treated with antibiotic therapy, surgery, leukocyte- and platelet-rich fibrin (L-PRF), and photobiomodulation; G2 was treated with antibiotic therapy and surgery; G3 was treated with antibiotic therapy and photobiomodulation. Various clinical variables and treatment protocols were analyzed to determine their correlation with the healing outcome at three and six months of follow-up. RESULTS: There was a significant association between the different treatment protocols and the outcomes at both three and six months follow-up (p = 0.001 and p = 0.002, respectively). No significant association was observed between the outcomes and MRONJ localization, MRONJ stage, duration of drug treatment, gender, diabetes, corticosteroid therapy, smoking habits, underlying disease, and history of chemotherapy at both three and six months follow-up. CONCLUSIONS: Our results show that the combination of antibiotic therapy, surgery, L-PRF, and photobiomodulation may effectively contribute to MRONJ management.

Computer-guided palatal canine disimpaction: a technical note.

AIM: To present a minimally invasive approach to solve the impaction of palatal canines using computer-guided orthodontic miniscrews. MATERIALS AND METHODS: Miniscrew-supported appliances for palatal canine disimpaction are performed with CAD/CAM technology. With adequate software, it is possible to match the STL files of the dental arch with the DICOM images of the maxilla, previously transformed into STL files. The ideal points for miniscrew insertion can be identified on the STL 3D model file on the basis of the width and thickness of the palatal vault. A software application allows for the design of the surgical guide, which is printed using a 3D printer. The virtual position of the planned miniscrews is transferred onto a printed dental cast on which the orthodontic device is realized. On the day of surgery, both the surgical guide and the orthodontic appliance are ready for use. RESULTS: Miniscrew insertion and palatal canine disimpaction can be achieved in one surgical procedure. CONCLUSION: The use of computer-guided skeletal anchorage allows for both the reduction of the biomechanical side effects typical of conventional treatment and the risk of damaging adjacent anatomical structures, increasing the effectiveness of treatment. Controlled clinical trials are necessary to evaluate more fully any advantages of this minimally invasive technique.

Impact of the SARS-Cov2 Pandemic on Orthodontic Therapies: An Italian Experience of Teleorthodontics

Abstract Objective: To assess the possibility of controlling patients at a distance according to principles of teleorthodontics to understand its possible usefulness in the future routine activity and the impact pandemic may have had on different types of orthodontic treatments. Material and Methods: One hundred orthodontic patients (57 F, 43 M, age 7-46) during quarantine were checked through videocalls and photos sent by patients following proper instructions. Three groups have been distinguished based on the type of therapy: A-fixed appliances; B-removable appliances; C-clear aligners. Relevant events about dental and gingival health, integrity of appliances, orthodontic therapies related symptoms and overall progress of treatments were recorded. Results: A and B groups reported higher percentages of gingival inflammation (27 and 22%), dental plaque (16 and 13%), deciduous tooth loss (8 and 16%). Bracket and attachment detachment were the most frequent events in A and C groups (22 and 23%). Pain and discomfort were reported in A and B groups (35 and 32%). Therapies continued to progress better in C (51% improved dental alignment) and B (31% improved malocclusions) groups. Conclusion: Orthodontics is safe and allows during emergencies to postpone checks. Everyday mobile-technology is useful in managing orthodontic patients unable to carry out in-person control. When their effectiveness equals other systems, treatments with clear aligners without attachments should be preferred in patients unavailable for regular checks.

Use of an anatomical mid-sagittal plane for 3-dimensional cephalometry: A preliminary study.

PURPOSE: Cone-beam computed tomography (CBCT) is widely used for 3-dimensional assessments of cranio-maxillofacial relationships, especially in patients undergoing orthognathic surgery. We have introduced, for reference in CBCT cephalometry, an anatomical mid-sagittal plane (MSP) identified by the nasion, the midpoint between the posterior clinoid processes of the sella turcica, and the basion. The MSP is an updated version of the median plane previously used at our institution for 2D posterior-anterior cephalometry. This study was conducted to test the accuracy of the CBCT measures compared to those obtained using standard posterior-anterior cephalometry. MATERIALS AND METHODS: Two operators measured the inter-zygomatic distance on 15 CBCT scans using the MSP as a reference plane, and the CBCT measurements were compared with measurements made on patients' posterior-anterior cephalograms. The statistical analysis evaluated the absolute and percentage differences between the 3D and 2D measurements. RESULTS: As demonstrated by the absolute mean difference (roughly 1 mm) and the percentage difference (less than 3%), the MSP showed good accuracy on CBCT compared to the 2D plane, especially for measurements of the left side. However, the CBCT measurements showed a high standard deviation, indicating major variability and low precision. CONCLUSION: The anatomical MSP can be used as a reliable reference plane for transverse measurements in 3D cephalometry in cases of symmetrical or asymmetrical malocclusion. In patients who suffer from distortions of the skull base, the identification of landmarks might be difficult and the MSP could be unreliable. Becoming familiar with the relevant software could reduce errors and improve reliability.

Orthodontic-Orthopedic-Surgical Treatment of Syndromic Third Class: Proposal of a New Craniofacial Cephalometric Method.

The management of patients suffering from class III due to syndromic craniosynostosis requires a multidisciplinary team to prevent and correct the complex clinical features related to the syndrome. Among the main clinical features, the midface hypoplasia requires surgical advancement with a rigid external distraction device. The comparison of pre- and postdistraction lateral cephalometries is often difficult in these patients, because the craniofacial advancement mobilizes the landmarks routinely used in cephalometry. Aim of this study is to evaluate occlusal, maxillary, and facial changes obtained after the midface osteodistraction using as reference the PM plane, that does not undergo postsurgical spatial modifications.The before and after surgery lateral X-rays of 12 patients were compared to test the cephalometric protocol: 10 angles and 11 linear distances were evaluated.The cephalometric comparison before and after osteodistractions of syndromic class III, using as reference the Enlow's PM plane, has confirmed the data present in current literature, consisting in forward and downward movements of facial middle 3rd, with clockwise rotation of the splanchnocranium and increase of the facial heights. The use of the PM plane as reference could be the solution to problems that have been an obstacle for the study of occlusal and facial changes in patients affected by craniofacial dysostosis.

Unilateral hemimandibular hyperactivity: Clinical features of a population of 128 patients.

PURPOSE: Facial asymmetries due to unilateral condylar hyperactivity are often a challenge both for maxillo-facial surgeons and for orthodontists; the current literature shows different opinions about aetiology, classification, treatment approach and timing. We made a retrospective study on patients suffering from unilateral condylar hyperactivity between 1997 and 2015 in our Department; clinical features and treatment options were grouped and compared with literature. METHODS: The descriptive analysis investigated variables like sex, age, side and direction of the asymmetry, condylar activity and type of intervention. RESULTS: The population was composed of 128 patients. The hemimandibular hyperactivity occurs equally in both sexes around the second decade, although the range of the first consultation goes from 7 to 49 y.o. The vertical hyperdevelopment group is almost equal to the horizontal. All the patients with horizontal hyperactivity showed negative scintigraphy and were treated with pre-surgical orthodontics and orthognathic surgery; patients with vertical hyperactivity and positive scintigraphy were treated with condylectomy and post-surgical orthodontics. CONCLUSION: In our group of patients, direction of the hyperactivity and results of the scintigraphy lead to treatment choice and timing. Further studies are necessary to explain why, in our group, all the patients with horizontal involvement are negative to scintigraphy.

The combined use of corticotomy and clear aligners: A case report.

OBJECTIVE: To describe an orthodontic treatment that combines an esthetic approach (clear aligners) with surgery (alveolar corticotomy). MATERIALS AND METHODS: A patient with moderate dental crowding and Class I skeletal and molar relationships was selected. Orthodontic records of the patient were taken. Periodontal indexes, oral health-related quality of life (OHRQoL), and treatment time were evaluated. After we reflected a full-thickness flap beyond the teeth apices, the cortical bone was exposed on the buccal aspect and a modified corticotomy procedure was performed. Interproximal corticotomy cuts were extended through the entire thickness of the cortical layer, just barely penetrating into medullary bone. Orthodontic force was applied on the teeth immediately after surgery. RESULTS: Total treatment time was 2 months. Periodontal indexes were improved after correction of crowding. A deterioration of OHRQoL was limited to 3 days following surgery. CONCLUSION: This case report may encourage the use, limited to selected cases, of corticotomy associated with clear aligners to treat moderate crowding.

The Influence of the Tolerance between Mechanical Components on the Accuracy of Implants Inserted with a Stereolithographic Surgical Guide: A Retrospective Clinical Study.

BACKGROUND: The stereolithographic-guided surgery system involves a sequence of diagnostic and therapeutic events, and errors can arise at different stages. In these systems, one of the potentially clinically relevant errors may be the mechanical errors caused by the bur-guide gap due to the presence of a rotational allowance of the drills in the tubes. PURPOSE: The purpose of this retrospective clinical study is to determine if it is possible to reduce the total error by limiting the tolerance among the mechanical components and to evaluate its clinical incidence. MATERIALS AND METHODS: Sixty-six implants were inserted using the External Hex Safe® (Materialise Dental, Leuven, Belgium) system (Group A), and 71 implants were inserted using the same system with mechanical components modified to minimize the tolerance (Group B). Regarding only the angular deviation values, the t-test was used to determine the influence of reduced tolerance among the mechanical components on the accuracy values. RESULTS: t-Test showed that there is a statistically significant better accuracy with the modified system (Group B). CONCLUSIONS: Limiting the error that originates from mechanical components, total error could be statistically significantly reduced. Mechanical error is one of the most important source of error using External Hex Safe stereolithographic surgical guide.

Dental anomalies and clinical features in patients with maxillary canine impaction.

OBJECTIVE: To analyze the prevalence, distribution, clinical features, and relationship with dental anomalies of maxillary canine impaction. MATERIALS AND METHODS: The complete pretreatment records of 1674 orthodontic patients were examined. Subjects with maxillary impacted canines were divided into two study groups: a palatally displaced canine (PDC) group (114 patients) and a buccally displaced canine (BDC) group (37 patients). These were compared to a control group of 151 patients who were randomly selected from the initial sample without maxillary canine impaction. The significance of associations between canine impaction and dental and clinical features and anomalies was examined with the chi-square test. RESULTS: PDC patients presented with normal overjet and facial profile and a lower degree of dental arch crowding in comparison to the control patients. PDC patients showed a higher prevalence of impaction of other teeth, dental aplasia, transposition, and peg-shaped maxillary lateral incisors (odds ratios 3.3, 2.6, 8.3, and 5.8, respectively). CONCLUSION: PDC was frequently the only orthodontic problem of patients. BDC group patients did not present with notable differences in clinical and dental features or dental anomalies compared to control subjects.

Accuracy of two stereolithographic surgical templates: a retrospective study.

BACKGROUND: The use of computer software and stereolithography for dental implant therapy has significantly increased during the last few years. The aim of this study was to evaluate and compare the mean accuracy and maximum deviations values of dental implant placement using two stereolithographic (SLA) guide systems. MATERIALS AND METHODS: Twenty patients were selected and 227 implants were inserted using bone-, tooth- and mucosa-supported SLA surgical guides. Thirty-one guides, both single- and multiple-type, were used. Some of the single-type surgical guides were fixed with osteosynthesis screws. A postoperative computer tomography (CT) was performed and an iterative closest point algorithm was used to match the jaw of the CT preoperative with the jaw of the postoperative CT. Quantitative data of each group were described. The t-test was used to determine the influence of the utilization of the different types of SLA on accuracy values. RESULTS: t-Test demonstrated a better accuracy of the multiple-type guides in almost all deviation values when the mucosa-supported guides were considered. Regarding the bone-supported template, the single-type fixed group showed a better accuracy while the highest values of deviation were registered by the multiple-type guides. The single-type group showed a better accuracy when the tooth support was considered. CONCLUSIONS: The results of the present study indicated best accuracy of the single-type guide using a bone or tooth support. The multiple-type guide recorded the best accuracy data when the mucosa support was considered comparing either a fixed and a not-fixed single-type guide.

Evaluation of alveolar cortical bone thickness and density for orthodontic mini-implant placement.

OBJECTIVE: Mini-implant stability is primarily related to bone quality and quantity. This study evaluated alveolar cortical bone thickness and density differences between interradicular sites at different levels from the alveolar crest, and assessed the differences between adolescents (12-18 years of age) and adults (19-50 years of age), males and females, upper and lower arch, anterior and posterior region of jaws and buccal and oral side. STUDY DESIGN: In this retrospective study, 48 Computed Tomography scans, performed for oral surgery purposes were selected from dental records of 3,223 Caucasian orthodontic patients. The SimPlant software (Materialise, Leuven, Belgium) was used to measure cortical bone thickness and density at 13 interradicular sites and four bone levels ( 2,4,6 and 8 mm ). For the statistical analysis descriptive statistics, Student's t-test and Pearson correlation coefficient were used. RESULTS: Statistically significant differences in alveolar cortical bone thickness and density between age, gender, sites and sides were found (P<0.05). The Pearson correlation coefficient demonstrated a significant linear increasing of thickness and density from crest to base of alveolar crest (P≤0.05). Conclusion. Adults show a thicker alveolar cortical bone than adolescents. Alveolar cortical bone thickness and density were greater in males than in females, in mandible than in maxilla, in the posterior region than the anterior, in oral than buccal side. There is an increase of thickness and density from crest to base of alveolar crest. Key words:Orthodontics, cortical bone thickness, cortical bone density, mini-implant, computed tomography, temporary anchorage devices.

Cognitive experience of oral cancer among young people of "Sapienza" University of Rome.

AIMS: the aim of this study was to analyse the awareness of oral cancer among young adults in the city of Rome. MATERIALS AND METHODS: during the orientation period for new graduates students, or "Porte aperte", organised by the Sapienza University of Rome in July 2009 and 2010, a survey among young people regarding their knowledge on the risk factors, the importance of early diagnosis, and the methods for primary and secondary prevention of oral cancer was conducted. A total of 1125 questionnaires were administered to subjects who agreed to respond to assess the level of knowledge of the disease. RESULTS: only 45.3% of the sample population was aware of the existence of oral cancer; among these individuals, 36.9% did not perceive seriousness of the malignancy. High school students who attended a scientific high school knew the risk factors better than the students who attended classical and technical high school. CONCLUSIONS: rigorous educational programs along with diagnostic strategies promise to reduce the burden of oral cancer. The data obtained from this study highlight the need to increase health education, especially among young people in humanistic or technical high schools and universities (Classical High School, Technical Institutes, Faculty of Letters, Faculty of Law) where there is a lack of knowledge concerning oral cancer prevention.