Effects of Thermoforming on the Mechanical, Optical, Chemical, and Morphological Properties of PET-G: In Vitro Study.

The effectiveness of clear aligners in correcting malocclusions is closely linked to the properties of the materials used to make them. The polymers used in the manufacture of clear aligners have well-established properties. However, the process of manufacturing clear aligners, known as thermoforming, involves thermal and mechanical shocks that may alter these properties. The objective of this study was to evaluate the effects of thermoforming on the mechanical, optical, chemical, and morphological properties of sixty PET-G specimens. The study compared the thickness, weight, absorbance, chemical structure, surface roughness, elastic modulus, yield strength, and breaking load of thirty thermoformed specimens with thirty non-thermoformed specimens. The study introduces a new approach by using standardized samples to analyze both chemical and physical properties. The results showed statistically significant differences in thickness (-15%), weight (-11%), and surface roughness (+1233% in roughness average; +1129% in RMS roughness) of the material. Additionally, a correlation was found between reduction in thickness and increase in opalescence. There was no significant change in the functionality of the aligners after thermoforming, as no significant mechanical changes were found. However, the increase in surface roughness may lead to plaque and fluid accumulation and worsen the fit of the aligners.

Short-term effect of orthodontic clear aligners on muscular activity and occlusal contacts: A cohort study.

INTRODUCTION: The simultaneous presence of maxillary and mandibular clear aligners alters the vertical dimension and the quantity and quality of occlusal contacts. Few data in the literature explain how this occurs and the effects on neuromuscular coordination. This study aimed to evaluate occlusal contacts and muscular balance during treatment with clear aligners over a short follow-up time. METHODS: Twenty-six female adult patients were enrolled in this study. The center of occlusal force (COF) was evaluated using a T-Scan II device, whereas muscular symmetry and balance were determined through surface electromyography using a standardized protocol that reduces anthropometric and electrode variations. Both evaluations were performed in centric occlusion and with aligners worn before treatment, after 3 months, and after 6 months. RESULTS: A statistically significant variation in COF position was reported in the sagittal plane but not in the transverse plane. The shift in the COF position was followed by a change in muscular balance evaluated through surface electromyography. CONCLUSIONS: Treatment with clear aligners resulted in an anterior shift of the COF when biting in centric occlusion and a posterior shift when the aligners were worn in healthy female patients after 6 months of observation. This change in occlusal contact was followed by an improvement in muscular function symmetry in the short term when aligners were worn, compared with the centric occlusion during treatment.

New Conservative Approach for the Management of Recurrent Sublingual Ranula-A Case Report.

Ranula is a rare and benign extravasation mucocele that is clinically characterized by asymptomatic sublingual or submandibular masses. Surgical excision is considered the most effective treatment approach, but it has been associated with high invasiveness and several complications (hemorrhage, damage to Wharton's duct, and lingual nerve injury). Over the past decade, more conservative therapies have been rapidly disseminated into clinical practice to seek a more effective and less traumatic approach for young patients. In this report, an 8-year-old female with an asymptomatic, recurrent sublingual ranula was treated using a conservative approach with marsupialization and an intracystic injection of a plaque remover (Hybenx® gel). After incision of the cystic dome, Hybenx® gel was applied into the cystic lumen for 20 seconds and then aspirated; next, the area was rinsed thoroughly with sterile saline solution before suturing. Ultrasound re-evaluation at 10 months and intraoral clinical examination at 24 months confirmed the absence of relapse. Our results support the hypothesis that marsupialization combined with intracystic injection of Hybenx® gel could be an encouraging conservative treatment alternative for recurrent sublingual ranula in children. Further randomized controlled trials are needed to test this hypothesis.

Analysis of the Changes in Occlusal Plane Inclination in a Class II Deep Bite "Teen" Patient Treated with Clear Aligners: A Case Report.

Background: Optimal management of hypodivergent growing patients demands a strict control of vertical dimension and to exploit the growth potential. If a deep bite malocclusion causes a traumatic contact between the upper and lower incisors and affects the facial appearance, an early interceptive treatment is recommended. The aim of this case report is to outline the clinical management of the occlusal plane of a growing Class II division 1 deep bite patient treated with aligners and Class II elastics. Methods: The treatment lasted 11 months and was divided into two phases. Treatment goals included improvement of the soft tissue profile and basal bone relationships through an increase in the mandibular third of the face and a sagittal advancement of the mandible. The correction of the curve of Spee involved intrusion of the mandibular incisors and extrusion of the mandibular premolars. Results: The cephalometric analysis at the end of the treatment displayed significant differences in the skeletal and occlusal pattern along with aesthetic improvements. Conclusion: The final cephalogram showed a consistency between the planned tooth movement and the clinical results. Although definitive recommendations must be withheld until longer follow-up is available, the patient presented here shows that the treatment protocol yielded positive mandibular growth.

Orthodontic Extrusion vs. Surgical Extrusion to Rehabilitate Severely Damaged Teeth: A Literature Review.

The need to rehabilitate severely compromised teeth is frequent in daily clinical practice. Tooth extraction and replacement with dental implant represents a common treatment choice. However, the survival rate for implants is inferior to teeth, even if severely damaged but properly treated. In order to reestablish a physiological supracrestal tissue attachment of damaged teeth and to arrange an efficient ferrule effect, three options can be considered: crown lengthening, orthodontic extrusion and surgical extrusion. Crown lengthening is considered an invasive technique that causes the removal of part of the bony support, while both orthodontic and surgical extrusion can avoid this inconvenience and can be used successfully in the treatment of severely damaged teeth. The aim of the present narrative review is to compare advantages, disadvantages, time of therapy required, contraindications and complications of both techniques.

Amelogenin-Derived Peptides in Bone Regeneration: A Systematic Review.

Amelogenins are enamel matrix proteins currently used to treat bone defects in periodontal surgery. Recent studies have highlighted the relevance of amelogenin-derived peptides, named LRAP, TRAP, SP, and C11, in bone tissue engineering. Interestingly, these peptides seem to maintain or even improve the biological activity of the full-length protein, which has received attention in the field of bone regeneration. In this article, the authors combined a systematic and a narrative review. The former is focused on the existing scientific evidence on LRAP, TRAP, SP, and C11's ability to induce the production of mineralized extracellular matrix, while the latter is concentrated on the structure and function of amelogenin and amelogenin-derived peptides. Overall, the collected data suggest that LRAP and SP are able to induce stromal stem cell differentiation towards osteoblastic phenotypes; specifically, SP seems to be more reliable in bone regenerative approaches due to its osteoinduction and the absence of immunogenicity. However, even if some evidence is convincing, the limited number of studies and the scarcity of in vivo studies force us to wait for further investigations before drawing a solid final statement on the real potential of amelogenin-derived peptides in bone tissue engineering.

Effect of Class II functional treatment on facial attractiveness, as perceived by professionals and laypeople.

The literature offers different perspectives for and against two-phase treatment of skeletal Class II malocclusion. Facial attractiveness is an important aspect to take into account, given that children with skeletal Class II are often bullied by their peers and have low self-esteem and a lower social perception. The aim of the present study was to evaluate the aesthetic perception of facial profiles by a large number of observers, before and after treatment with a functional appliance, compared to untreated controls. The pre- and post-treatment cephalograms of 20 Class II subjects treated with Sander's bite-jumping appliance and 20 untreated historical controls were collected and transformed into black and white silhouettes depicting only the lower third of the face. An online questionnaire comprising the silhouettes of the two groups, three "calibration" profiles and an "ideal" profile was submitted to dentists, orthodontists, undergraduates and laypeople, asking them to rate the profile's attractiveness using a Visual Analogue Scale (VAS). The effect of treatment, and observers' age, expertise and gender were analysed. The calibration images and the ideal profiles were used to evaluate the coherence of each observer's judgement. The protocol was approved by the local Ethics Committee. Nine-hundred and ten questionnaires were collected. Treated subjects showed a larger improvement of facial attractiveness compared to controls. A significant effect of gender on the observer's ratings was observed. Some observers showed incoherent judgement, which had a significant effect on the regression model. In conclusion, early treatment with functional appliances seems to improve patients' facial aesthetics. This improvement is perceived equally by dental professionals and laypeople.

Radiographic Assessment of Pediatric Condylar Fractures after Conservative Treatment with Functional Appliances-A Systematic Review.

BACKGROUND: To evaluate the effectiveness of conservative treatment with functional appliances for condylar fractures in pediatric age. METHODS: Four electronic databases (PubMed, EBSCO, Scopus, and Web of Science) were consulted with no restriction of publication status or year, up to 31 August 2020. SELECTION CRITERIA: based on the PICOS criteria, the selection criteria were set for observational human studies, with at least 10 patients and six months of follow-up. The study population included pediatric patients (aged 5-16 years), with unilateral or bilateral condylar fracture, treated with functional appliances. Condylar remodeling and mandibular growth were analyzed through sequential radiographic examinations. DATA COLLECTION AND ANALYSIS: Two independent reviewers carried out title-abstract screening, and a senior investigator was involved to solve any disagreement. The quality of the evidence was assessed through the Canada Institute of Health Economics (IHE) quality appraisal checklist, and the National Institutes of Health (NIH) quality assessment tool. RESULTS: A total of 971 articles were retrieved from the electronic search; among them, three studies met the eligibility criteria. A moderate risk of bias was detected in all the studies, due to common limitations (absence of multicenter studies, prospective design, blindness of the investigators, patients' drop-out). At follow-up examinations (between 6 months and 4.9 years), the difference of condylar neck length between the "injured" and "healthy" side was approximately 2 mm, while the anteroposterior condylar width discrepancy was recorded up to 1 mm. CONCLUSIONS: Short- and long-term data revealed that conservative treatment with functional appliances led to partial or full radiological recovery of the joint morphology, along with good to excellent functional results. Patients' age has a crucial role on the treatment choice, and the type of fracture (presence of condylar displacement, or dislocation) is also a major prognostic indicator of the radiologic outcome. LIMITATION: To confirm the effectiveness of functional appliances, more prospective clinical long-term follow-up studies with homogeneous samples of condylar fractures are deemed necessary. Registration: The study protocol was registered on PROSPERO (CRD42020205650).

Indication of clear aligners in the early treatment of anterior crossbite: a case series.

INTRODUCTION: Anterior crossbite (AC) is defined as a reverse sagittal relationship between maxillary and mandibular incisors. According to an evidence-based orthodontic triage, the treatment need of AC is indicated if any occlusal interference is forcing the mandible towards a Class III growth pattern. Removable and fixed appliances have been suggested to correct AC. OBJECTIVE: The present report aims at presenting the benefits of an alternative therapy for the early treatment of anterior crossbite using clear aligners. METHODS: Two cases of anterior crossbite corrected using clear aligners in 8-years-old children are presented. RESULTS: In both cases, AC was successfully corrected within 5 months. At the end of the treatment, overjet and overbite were corrected. No major discomfort or speech impairment was noticed by the parents. CONCLUSIONS: Due to the perceived shortcomings of alternative approaches, the use of clear aligners for correcting AC in mixed dentition should be considered as a comfortable and well tolerated appliance for young patients.

Clinical Effects of Mercury in Conservative Dentistry: A Systematic Review, Meta-Analysis, and Trial Sequential Analysis of Randomized Controlled Trials.

METHODS: A systematic literature search was conducted in four electronic databases (Ovid via PubMed, Web of Science, Scopus, and CENTRAL) including all available randomised controlled trials published in the last 15 years comparing the use of dental amalgam with composite resins in humans with a follow-up period of at least one year. The primary outcome was the Hg concentration in biological fluids (urine, hair, blood, and saliva) with the aim of assessing their reliability as biomarkers of Hg exposure. The risk of bias was assessed through the Cochrane Collaboration tool and the overall quality of evidence through the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system. The results of the meta-analysis were expressed using a random-effects model, and their power was assessed through the trial sequential analysis (TSA). RESULTS: From the initial 2555 results, only 6 publications were included in the review: five were considered as having high risk of bias, whereas one as having moderate risk. Only two articles were eligible for quantitative analysis. The meta-analysis gathered data from 859 patients but was nevertheless not significant (p = 0.12). The TSA confirmed this evidence revealing that it was due to a lack of statistical power since the required information size (RIS) threshold is not reached. CONCLUSIONS: The existing evidence revealed that there are not enough data to support the hypothesis that restorations with dental amalgam can cause nephrotoxicity when compared with composite resins restorations.

Indication of clear aligners in the early treatment of anterior crossbite: a case series

ABSTRACT Introduction: Anterior crossbite (AC) is defined as a reverse sagittal relationship between maxillary and mandibular incisors. According to an evidence-based orthodontic triage, the treatment need of AC is indicated if any occlusal interference is forcing the mandible towards a Class III growth pattern. Removable and fixed appliances have been suggested to correct AC. Objective: The present report aims at presenting the benefits of an alternative therapy for the early treatment of anterior crossbite using clear aligners. Methods: Two cases of anterior crossbite corrected using clear aligners in 8-years-old children are presented. Results: In both cases, AC was successfully corrected within 5 months. At the end of the treatment, overjet and overbite were corrected. No major discomfort or speech impairment was noticed by the parents. Conclusions: Due to the perceived shortcomings of alternative approaches, the use of clear aligners for correcting AC in mixed dentition should be considered as a comfortable and well tolerated appliance for young patients.

RESUMO Introdução: A mordida cruzada anterior (MCA) é definida como uma relação sagital reversa entre os incisivos superiores e inferiores. De acordo com a evidência científica, o tratamento da MCA é indicado em casos em que a interferência oclusal favorece o crescimento mandibular em direção a um padrão de Classe III. A literatura descreve diversos aparelhos removíveis e fixos para a correção dessa má oclusão. Objetivo: A presente série de casos tem como objetivo apresentar os benefícios de uma terapia alternativa para o tratamento precoce da MCA por meio do uso de alinhadores transparentes. Métodos: Apresentação de dois casos de MCA tratados com alinhadores transparentes em crianças de 8 anos de idade. Resultados: Em ambos os casos, a MCA foi corrigida com sucesso em um período de 5 meses. Ao fim do tratamento, obteve-se sobressaliência e sobremordida ideais. Segundo o relato dos pais, nenhum grande desconforto ou comprometimento na fala foi observado. Conclusões: Tendo em vista os problemas associados a algumas abordagens alternativas, o uso de alinhadores transparentes para correção da MCA durante a dentição mista pode ser considerado confortável e bem tolerado por pacientes jovens.

Custom made onlay implants in peek in maxillofacial surgery: a volumetric study.

PURPOSE: Facially malformed patients often present a variable degree of facial imbalance even after basal bone correction, and resolution of the residual hard- and soft-tissue deficiencies and asymmetries of the face are of great importance for achieving a satisfactory post-implant procedure result. The use of polyether ether ketone (PEEK) implants for maxillofacial reconstruction has been documented in the literature, but the number of patients who have received them is limited. The aim of this study was to evaluate the overall volumetric results in patients with facial imbalance after onlay custom implant positioning for mandible and fronto-orbital reconstructions. Analysis was performed by confronting volumes with the use of three-dimensional (3D) photogrammetry. METHODS: Fifteen patients were eligible for PEEK implant placements, eight for mandibular angle reconstruction, and seven for fronto-orbital reconstruction. Pre- and post-surgical 3D images of each patient's face were acquired. Facial asymmetry was analyzed by comparing each face with its mirrored copy. RESULTS: Three-dimensional analyses have shown that some degree of volume imbalance was still present in the patients with only 1.32 ± 1.02 mm residual discrepancy after treatment. CONCLUSION: Results of the study were found to fall within clinically acceptable limits since an asymmetry rate of < 3 mm is considered to fall into the norm.

Orthodontic treatment of class three malocclusion using clear aligners: A case report.

Class III malocclusion is a growth-related challenging condition for orthodontists. We present a case of a 11-year-old girl with a skeletal class III malocclusion with bilateral cross bite, and a functional shift of the lower dental midline. A multiphase clear aligners' treatment was scheduled with the aim of removing all dental interferences which involved an anterior displacement of the mandible. At one-year follow-up, clear aligners' therapy resulted in skeletal and dental improvements. Clear aligners therapy represents a valid alternative to fixed appliance therapy in the early interception of class III malocclusion. The present manuscript was prepared following the CARE guidelines.

Volumetric analysis of cleft lip deformity using 3D stereophotogrammetry.

PURPOSE: To quantify and compare pre-operative and post-operative volumetric adjustments of the upper lip tissues in patients with cleft lip. METHODS: The authors performed an anthropometric study and a quantitative analysis of the differences based on three-dimensional morphology of the nasolabial area. Twenty facial images using the three-dimensional stereophotogrammetry were taken from ten selected subjects on two separate occasions, sitting in natural head position. Facial landmarks were marked and measurements recorded, in order to calculate the volumetric adjustments in the soft tissues of the upper lip, comparing the preoperative and postoperative results. Student test and p-Value were performed for statistical analysis. RESULTS: The analysis of the 3D images showed variability with the pre- and postoperative volumes of the nasolabial area with: an increase of upper lip volume all patients; a complete view of the severity in the preoperative; and an improvement of the appearance in the postoperative. The amount of increase of the upper lip volume was established about 29,7%. For all measurements, the variability between pre- and post-operative was significant (p < 0.01). CONCLUSION: The 3D stereophotogrammetry technique allows a detailed preoperative evaluation and an accurate assessment of the surgical outcomes. The study provides a value of volumetric variation of the upper lip in individuals with cleft lip. KEY WORDS: Cleft lip, Nasolabial area, 3D Morphological Analysis, 3D Stereophotogrammetry, Upper lip volume.

Case Reports in Pediatric Dentistry Journals: A Systematic Review about Their Effect on Impact Factor and Future Investigations.

Background: The effects of publishing case reports on journal impact factor and their impact on future research in pediatric dentistry has not been clearly evaluated yet. Aim. To assess the relevance and role of case reports in pediatric dentistry. Methods: A systematic review (PROSPERO registration number: CRD42018108621) of all case reports published between 2011 and 2012 in the three major pediatric dentistry journals was performed manually. Data regarding citations of each report were acquired from the Institute for Scientific Information database available online. The authors analyzed information regarding citations (number, percentage, and mean) received by each case report and considered their relation with the 2013 journal impact factor. Results: Case reports accounted for almost sixteen per cent of all articles published between 2011 and 2012. The citation rate of case reports was generally low and the highest mean citation was 0.5. This review revealed that 6 (9.52%) case reports had at least 5 citations and that the majority of the citing articles were also case reports (27.78%) or narrative reviews (25%). Conclusions: The publication of case reports affected the journal impact factor in a negative way, this influence is closely related to the percentage of the published case reports. Case reports about innovative topics, describing rare diseases, syndromes, and pathologies were more frequently cited.

Lay People Esthetic Evaluation of Primary Surgical Repair on Three-Dimensional Images of Cleft Lip and Palate Patients.

Background and Objectives: Previous literature has disclosed that facial attractiveness affects the esthetic evaluation of nose and lip deformity on frontal and lateral photographs. However, it has never been debated if the removal of the external facial features on three-dimensional (3D) models ("cropped assessment bias") could provide a considerable usefulness in the interpretation and comparison of the results. Additionally, it has been assumed on two-dimensional (2D) studies that esthetic assessment biases with respect to observer gender, and it is not acknowledged if and to the extent that "gender assessment bias" may be influenced by a three-dimensional layout. The aim of this study is to investigate if facial traits and observers' gender may affect the esthetic ratings of unilateral cleft lip and palate (UCLP) patients after soft tissue reconstruction. Materials and Methods: Three-dimensional images of ten UCLP patients' images were acquired before the intervention (T0), one-month (T1) and six-months (T2) postoperative. Geomagic® software (version 2014; 3D Systems, Rock Hill, SC, USA) was used to remove the external facial features of 3D surface models. Five-point scale developed by Asher-McDade et al. was used to rate both nasolabial attractiveness and impairment for full-face (FF) and cropped-face (CF) 3D images. Forty-three judges (21 males, 22 females) were enrolled for the esthetic evaluation. Intraclass correlation coefficient (ICC) was used to test intra- and inter-examiner reliability; a value of 0.7 was set as the minimum acceptable level of reliability. Results: When comparing the 2 sets of observations (FF and CF), the ICC ranged from 0.654 to 0.823. Concerning gender assessment bias, the ICC ranged from 0.438 to 0.686 and from 0.722 to 0.788 for males and females, respectively. Concerning inter-examiner reliability, ICC for questions 2-7 ranged from 0.448 to 0.644 and from 0.659 to 0.817 at T0 and T2, respectively. Conclusions: The removal of external facial features provides subtle differences on the esthetic assessment of UCLP patients. Moreover, based on our data, examiners' gender differences may affect esthetic assessment of UCLP patients. Despite the subjectivity of esthetic judgments, a reliable, validated and reproducible scoring protocol should consider the influence of gender differences on 3D esthetic assessment of UCLP patients.

Zimmermann-Laband-1 Syndrome: Clinical, Histological, and Proteomic Findings of a 3-Year-Old Patient with Hereditary Gingival Fibromatosis.

BACKGROUND: Zimmermann-Laband-1 syndrome (ZLS-1; OMIM# 135500) is a rare genetic disorder whose oral pathognomonic sign is the development of progressive, diffuse, and severe gingival hypertrophy. Most children with abnormally gingival hyperplasia may also present multiple unerupted teeth and skeletal deformities of maxillary arches (i.e., skeletal anterior open bite). Despite phenotypic variability of the clinical spectrum, gingival fibromatosis is the hallmark of ZLS-1. METHOD: In this study, we report a 3-year-old male patient with a ZLS-1-related gingival overgrowth and failure of eruption of the deciduous teeth in the molar area. Surgical excision was performed under general anesthesia. RESULTS: At three weeks follow-up, esthetics was significantly improved in terms of gingival appearance, and teeth eruption allowed an adequate masticatory function. CONCLUSION: In severe cases, surgical removal of the hyperplasic fibrous tissue may be required to expose unerupted teeth and establish a proper gingival contour. Surgical excision under general anesthesia is an elective procedure for patients with special needs, mental disability, as well as young and adult patients with dental anxiety type II and IV associated with poor oral health.

Three-Dimensional Assessment of Morphological Changes Following Nasoalveolar Molding Therapy in Cleft Lip and Palate Patients: A Case Report.

The applications of computer-guided technologies for three-dimensional image analysis provide a unique opportunity to quantify the morphological dimensional changes of the face in a practical and convenient way. Symmetry of the nasolabial area is one of the main factors of facial attractiveness as well as being the main objective of the treatment of cleft lip and palate (CLP). Technological advances in computer-guided visualization modes and their applications to three-dimensional stereophotogrammetry provide more practical opportunities and alternatives for facial analysis. Each study, however, uses different protocols for the acquisition and analysis of three-dimensional images. In addition, each study identifies different anthropometric points and calculates linear and angular measurements with overlapping protocols. Therefore, it is appropriate to define a standardization of the three-dimensional analysis of CLP patients to compare the studies of different research centers. The aim of this report is to propose a protocol to standardize the acquisition and analysis of three-dimensional images to evaluate the three-dimensional changes in the nasolabial area in cleft lip and palate patients undergoing pre-surgical nasoalveolar molding (PNAM).

How to Manage Impacted Third Molars: Germectomy or Delayed Removal? A Systematic Literature Review.

OBJECTIVES: The aim of this systematic review is to evaluate and compare the risks and benefits of germectomy and delayed removal of third molars and develop a patient management algorithm for second molar eruption in syndrome/incompliant patients. MATERIALS AND METHODS: A literature search was performed in the following databases; the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, Scopus, and Web of Science. Last search was done on July 2nd, 2018 including articles published from the last 18 years. The search aimed to identify all relevant studies written in English language. Gray literature was excluded. Risk of bias was evaluated with specific predetermined criteria. This systematic literature review was reported according to the PRISMA-P statement and was registered in the PROSPERO database with the following protocol ID: 104261. RESULTS: Literature search war performed on July 2018 and updated on February 2019. A total of 1610 articles were screened. After abstract screening and discarding duplicates, 86 full-text articles were obtained and subjected to additional evaluation. Four articles were included in the review. Three studies were considered as having a medium risk of bias and one was assessed as at high risk. Due to the heterogeneity of presenting results and a very low number of included studies a quantitative analysis was not possible. Only qualitative analysis was made. Considering the limited number of studies included and the level of risk of bias there is no sufficient evidence to state the benefits of preventive removal of impacted third molars, especially in patients with poor oral hygiene due to intellectual disability. Early germectomy represents an elective approach of pathologic alteration of tooth germ; orthodontic issues meet appropriate indication for a delayed removal. CONCLUSIONS: Given the best evidence-based information regarding patients' medical condition, we highlight the need to provide an ethical-based comprehensive approach in the diagnostic workflow and the assessment of treatment outcome.

Three-dimensional prediction of roots position through cone-beam computed tomography scans-digital model superimposition: A novel method.

OBJECTIVES: To introduce a new, fast, reliable, and free from software-related bias method to predict three-dimensionally the root position and angulation during and after orthodontic treatment. The final goal is to keep to a minimum the use of ionizing radiation by eliminating the necessity of multiple radiation exposure for checking root alignment. SETTING AND SAMPLE POPULATION: Pre- and post-treatment digital models and cone-beam computed tomographic (CBCT) scans from a patient were retrieved. MATERIAL AND METHODS: The post-treatment digital model (post-model) was set as the reference; pre- and post-treatment CBCT scans were pre-aligned to the post-model with a point set registration; iterative closest point algorithm was then employed for final adjustments. The accuracy of the proposed method was assessed by comparing the average distance between the expected root position setup with the true position of the roots, as from the post-treatment CBCT. RESULTS: After crown superimposition, 3D colour maps showed that the accuracy of the root prediction was below 0.1 mm. CONCLUSION: The proposed digital workflow allows to predict in an accurate and truly three-dimensional way the final position of roots, when an initial CBCT is available, without the need of an extra X-ray examination for the patient at the end of treatment. The limitation of the exposure to mid- and post-treatment X-rays is in accordance with the ALARA (As Low As Reasonably Achievable) principle and it is even more relevant in growing patients.