College of Dentistry Thesis and Dissertations

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In Vitro and In Vivo Assessment of Amelogenin Peptides Compared to Emdogain
(2021-04-26) Worsham, Theresa Adria; Luan, Xianghong; Diekwisch, Thomas; Kramer, Phillip
Objectives: To identify a cost-effective and well-defined alternative to currently available enamel matrix derivatives for periodontal regeneration. Methods and Materials: For in vitro studies, human periodontal ligament cells (PDLCs) were treated with Emdogain (EMD), recombinant human AMEL isoforms rh174, rh163 and rh146 or synthetic amelogenin peptides sh147-163 and sh164-174 at a concentration of 10 g/ml for 3, 7, 14 and 21 days on human periodontal ligament cells (PDLCs). Enamel protein function was assayed using wound healing and differentiation assays. For in vivo studies, collagen sponges (COL) were coated with human AMELs and EMD and implanted into C57 mouse skin subcutis or alveolar bone defects for 8 weeks, dissected and processed. Results: Enamel protein derivative effects on PDLC differentiation fold-changes varied from 1.94(rh174), 1.4(rh163), 1.76(rh146)(amelogenin isoforms), 2.64(sh147-163) and 4.47(sh164-174)(amelogenin peptides), to 1.18(EMD). The two synthetic peptides shAMEL164-174 (10-fold versus EMD) and shAMEL147-163 (4-fold versus EMD) also proved more effective in terms of wound healing capacity. Subcutaneous collagen implants treated with sh164-174/Col, sh146-163/Col, EMD/Col and BSA/Col demonstrated migrated MSCs surrounded by new extracellular matrix in the sh164-174/Col and EMD/Col scaffolds while there were only individual cells in the sh146-163/Col and the BSA/Col scaffolds. MicroCT analysis revealed high bone volume to tissue volume ratios in the sh146-163 (0.42) and sh164-174 (0.44) groups versus 0.34 (periodontitis group), and 0.32 (EMD group), respectively. Histological assessment indicated that only sh164-174 treatment promoted mature bone formation and periodontal ligament reattachment to the tooth root, while the PDL remained delaminated in the EMD, sh146-163 and control groups. Conclusion: When applied to periodontal defects in periodontitis animal models, shAMEL164-174 recruited mesenchymal stem cells, promoted periodontal ligament re-attachment and enhanced alveolar bone regeneration with superior effects on periodontal soft tissue wound healing and alveolar bone regeneration and without the effects of porcine EMD non-defined components.
Erythropoietin – a Potent Factor for Alveolar Ridge Augmentation after First Molar Extraction
(2020-04-03) Saxon, Matthew Keith; Diekwisch, Thomas G.H.; Luan, Xianghong; Gonzalez, Marianela
Purpose of the Research: Loss of teeth is commonly associated with a loss of the alveolar bone surrounding the functional tooth, resulting in an undesirably narrow bone ridge for subsequent implant placement. In our quest for alternatives to freeze-dried bovine bone, allografts, alloplasts, or RhBMP-2 we identified the kidney derived growth factor erythropoietin (EPO) as a candidate molecule for alveolar ridge augmentation in combination with suitable scaffolds. Currently, EPO overall safety in patients is established by current approval for Erythropoietin and biosimilars by the US Food and Drug Administration for the treatment of anemia caused by chronic kidney disease, chemotherapy, or use of zidovudine in patients with HIV infection. The aim of the present study is to evaluate the efficacy of erythropoietin’s angiogenic and osteogenic potential compared to two popular ridge preservation techniques; anorganic bovine bone mineral (Bio-Oss®) with non-cross-linked collagen membrane (Bio-Gide®), and collagen membrane alone. Methods and Materials: Rats underwent bilateral maxillary first molar extraction, and uniform extraction defects were made. Rats were randomly assigned to groups that were to receive an erythropoietin-soaked collagen pellet (Test Group), an anorganic bovine bone group (Bio-Oss® Geistlich Biomaterials) treatment group or no material (Control). Defects were then covered with Bio-Gide collagen membrane and secured with purified cyanoacrylate (Periacryl, Salvin®). The rats were then randomly assigned for sacrifice via CO2 overdose after four or eight weeks. The following analyses were performed; reverse transcriptase polymerase chain reaction (RT-PCR), radiographs, paraffin sections with Masson’s trichrome staining. Ground sections were subjected to Von Kossa staining. Results: X-ray, and Von-Kossa stain comparison demonstrated comparable bone fill and radiopacity in the extraction sockets of EPO and of anorganic bovine bone treated rats. The extracellular matrix of erythropoietin treated groups appeared to show an organized, sheath-like matrix compared to the control and anorganic bovine bone groups. RT-PCR data showed statistically significant increases in crucial genes for osteoblast regulation, and new blood vessel formation. Discussion: Our data indicate that EPO acts as a potent factor in combination with a collagen sponge, promoting both new bone and angiogenesis. Conclusions: Our study suggests that EPO or biosimilars might serve as an alternative to established procedures for alveolar ridge augmentation.
Effect of the Leaded Glasses as an Exomass Object on CBCT Images
(2023-07-24) Shahmirzadi, Solaleh; Liang, Hui; Nair, Madhu K; Tahmasbi Arashlow, Mehrnaz; Jalali, Poorya
Objectives: To investigate the effect of artifacts in cone-beam computed tomography (CBCT) arising from leaded-glasses located in the exomass on detection of root fracture (RF) and MB2 canal, and to test different image-acquisition parameters to reduce them. Methods: CBCT scans of a human cadaver head were acquired with the 3D-Accuitomo 170 utilizing FOV of 100 × 50 mm, which placed the leaded-glasses outside the field of view (FOV). Scanning parameters considered three conditions of standard/high resolution, full/partial rotations, with/without leaded-glasses. Six evaluators assessed the images for the presence of RF and MB2 and the quality of the images. For artifact measurement at different distances from the exomass, the standard deviation (SD) of grey values in three specified axial slices at different levels was obtained. The effects of the parameters and their interactions were evaluated by Analysis of Variance (α = 5%). Results: Fixed effects, estimated for various resolutions, rotation 360°/180°, and the presence or absence of the exomass, were not statistically significant on detection of RF (i.e. these factors had no impact on the detection of RF). Exomass had a significant negative effect on identifying MB2 (i.e. the readers were less able to detect the MB2 where exomass were present). The fixed effects of the rotation 360°/180° and resolutions were not statistically significant. The effect of exomass on image quality was significantly negative, while the effects of wider arc and higher resolution was significantly positive. The closest slices to the exomass produced the highest standard deviation (SD) values (more heterogeneous gray values, corresponding to greater artifact expression), followed by middle, and farther slices. These findings demonstrated that the artifact intensity was negatively influenced by the presence of the exomass and by the image slice's distance to the exomass (p < 0.05). Conclusions: Metallic exomass creates artifacts, which lower the image quality. The detection of RF is unaffected by exomass artifacts. Therefore, leaded-glasses may be worn by patients with suspected RF during CBCT scans to reduce the dose to the lens of the eye and lower the chance of developing cataract.
Wnt Lrp4 Knockout Mice Show Supernumerary Teeth and Fused Molars
(2023-06-19) Khan, Iqra Asad; Ruest, Louis B.; Wang, Qian; Jing, Yan
Several signaling mechanisms, notably the Wnt/β-catenin signaling system and its modulators, control tooth development. Lrp4 is recognized as one of these modulators that inhibits the pathway. In the absence of Lrp4, the Wnt/β-catenin signaling pathway is hyperactive, and in Lrp4-deficient mice, this leads to dental abnormalities like supernumerary teeth and fused molars. In this study, we use Wnt Lrp4flox/flox knockout mice to show these effects. The knockout mice were examined for supernumerary teeth, fused molars and alterations in tooth size. This demonstrates the consequences of Lrp4 deficiency on mouse tooth formation.
Precision Periodontics at Texas A&M University
(2023-04-28) Bowers, Stephanie Catherine; Parra Carrasquer, Carlos; Burch, Dan; Ouyang, Hongjiao
The treatment of chronic diseases, like periodontal disease, is sophisticated and sometimes costly to both patients and clinicians. As a result, an emerging trend is to provide precise and customized treatment to each patient to optimize the treatment outcomes. Current clinical periodontal decision making seeks to address a variety of disease criteria such as clinical presentation, diagnosis, radiographic appearance, clinician preference, and patient-related factors with individual patient treatment approaches, including non-surgical scaling and root planning, guided tissue regeneration, biological regenerative strategies, extracting diseased teeth, and more. Unfortunately, at present, there is a lack of literature defining biomarkers predicting clinical periodontal treatment outcomes. Gingival tissue was collected from patients with moderate or severe periodontal disease during one of three procedures: (i) scaling and root planing, (ii) open flap debridement with or without osseous recontouring, or (iii) guided tissue regeneration. GCF was collected at baseline (prior to procedure) and at approximately 1 month and 9 months. Gingival index and Plaque index were recorded at 9 months. Treatment outcome was recorded at 9 months as response (probing depths < 5 mm) vs. no response (any probing depths > 5 mm). On a single cell level, extracellular matrix pathways were substantially downregulated in both epithelial and stromal cell populations, and the level of downregulation was proportionate to the severity of the disease. Gene ontology (GO) enrichment comparisons demonstrated an increase in B-cell and T-cell activity with increased periodontal disease severity and elevated levels of complement activation and inflammatory response GOs in B-cells and T-cells. Desmoplakin and junction plakoglobin were downregulated in responders versus non-responders. Together, these data present the first comprehensive analysis of gene expression ontology-level changes in response to periodontal disease states and treatment and presents the identification of possible biomarkers for predicting periodontal treatment outcomes.
Effect of Print Orientation, Storage Conditions, and Time on the Intaglio Surface Accuracy of Additively Manufactured Implant Surgical Guides
(2023-05-11) Salazar Rios, Alma Liliana; Kontogiorgos, Dimitrios I; Kesterke, Matthew J; Revilla-Leon, Marta
Statement of problem. The accuracy of additively manufactured (AM) implant surgical guides can be affected by several factors that negatively impact the pre-planned implant position. How the print orientation and storage time and conditions influence manufacturing accuracy remains uncertain. Purpose. The purpose of the present in vitro study was to evaluate the influence of the print orientation, storage time, and storage conditions on the accuracy of AM surgical guide manufactured by using a stereolithography (SLA) 3D printer. Material and methods. A power analysis was performed in order to determine the adequate sample size. A tooth-supported maxillary implant surgical guide design was used to fabricate forty specimens (n=10). Four groups were created based on the print orientation used: 0 (Group 0), 45 (Group 45), 70 (Group 70), and 90 (Group 90). The specimens were fabricated using a desktop SLA 3D printer (Form 3B+) and biocompatible dental resin (Surgical Guide Resin V1) following the manufacturer’s recommended protocol. Each group was further divided into 2 subgroups based on the storage conditions: light (L subgroup) and dark (D subgroup) settings. Each group of specimens were digitized using a desktop scanner (Medit T710) at days 0, 1, 7, and 14 and stored at 20 degrees Celsius. The STL files of the scanned surgical templates were superimposed using the master design file using the best-fit alignment in a surface matching software program (Control X). The dimensional differences between the specimens STL files and the master STL file at the intaglio surface of the specimens was computed and analyzed. A single individual performed the data collection. For statistical tests, non-parametric tests for all samples were used Wilcoxon signed rank tests for angulation and storing time within groups, and Mann-Whitney U test for the storing conditions between groups. Results. Root mean square error (RMSE) values demonstrated that the 0-degree group had the highest accuracy. Statistically significant differences were observed between the 0-degree and 45-degree groups (p<0.001), the 0-degree and 90-degree groups (p<0.001), the 45-degree and70-degree groups (p<0.001), and the 70-degree and 90-degree groups (p<0.001). The comparison between light versus dark storage condition was not statistically significant (p-value=0.161). The difference between the specimens over time (day 0, 3, 7, and 14) were analyzed and did not reveal any statistical significance. Conclusion. The accuracy of surgical guides on the intaglio surface is affected in a statistically significant manner by the print orientation but not by the storage conditions over time. The present study suggests the zero-degree print orientation produces the most accurate surgical guides and the 45-degree print angulation the least accurate. Also, the assessed storage conditions (dark vs light) over the evaluated 14-day time period do not affect accuracy in a statistically relevant manner.
Evaluation of Accuracy and Dimensional Stability Over Time of 3D Printed Custom Trays, Using Two Different Types of Printing Resins
(2023-05-10) Koukousaki, Ioanna; Kesterke, Matthew; Kontogiorgos, Dimitrios; Chen, Jenn-Hwan
Statement of problem: Taking an accurate edentulous impression is the first step in complete denture restoration and is key to ensuring that the complete dentures will have good support, retention, and stabilization functions. To ensure intra-oral stability the retention of the denture, the custom tray should be closely adapted to the intraoral tissues and should be dimensionally stable from printing time to impression appointment. In the clinical setting, the accuracy of custom trays manufactured by traditional methods may be related to the experience of the operators, the change of uneven wax thickness, and the deformation of custom trays in the whole process. 3D printed custom tray workflows have been introduced and are continuing to emerge in modern dentistry. Purpose: The aim of this study is to investigate the intaglio surface trueness and dimensional stability of the digitally designed and 3D printed custom trays using two different types of printing resins over a 21-day period. Materials & Methods: Two maxillary and mandibular arches were scanned in a laboratory scanner to create a master file. Maxillary and mandibular custom trays were digitally designed, and 40 trays were printed in an LCD 3D printer. Four separate groups (n = 10) were fabricated using two different types of resin. Specimens were scanned at five-time intervals time “0” (t0), on the 3rd day (t1), on the 7th (t2), on the 14th (t3) and on the 28th (t4). Scans were measured for deviations from the reference trays. Statistical analysis was performed using Kruskal-Wallis with Bonferroni corrections (α= 0.05).
The Effect of Different Screw Angulations on the Fracture Resistance of Implant Zirconia Single Crowns Made on Two Different Implant Platforms
(2023-05-11) Siriwittayacharoen, Chitipat; Chen, Jenn Hwan; Kesterke, Matthew J.; Lin, Ju Ying
Purpose: The aim of this study was to investigate the effect of different implant screw channel angulation and implant platform on the fracture resistance of zirconia abutments without artificial aging. Materials and Methods: ten implant replicas were mounted in printed resin block at 30 degrees angulation to vertical axis for each group. Sixty samples of NobelBiocare® conical connection implant restorations were divided into two implant platforms (regular and narrow platform), then each platform consisted of three different angulation of screw access channels (0-degree, 15-degree, and 25-degree). #8 implant single restoration was designed with Exocad and used this design as a template to fabricate every restoration for each sample to make sure that every restoration has the same dimension. The STL files for each group (N0, N15, N25, R0, R15, R25) were sent to the milling center to fabricate screw-retained monolithic 3Y-TZP single crown restorations. After that, the restorations were bonded to Dynamic TIBASE® abutment and torqued to 25Ncm on implant replicas that were mounted on resin blocks. The universal testing machine was used to test the fracture strength of each sample with 5mm/min crosshead speed. Fracture strengths were recorded in Newtons (N). The peak force measured prior to screw loosening or permanent deformation at the connection of the implant abutment was recorded for each specimen. All statistics and analyses were computed using SPSS software (SPSS Statistics version 28.0, IBM). Due to non-normal distributions, non-parametric Kruskal Wallis test for multiple tests were performed between and within groups comparisons with an α = .05 for all tests. Results: The median compressive force values for all the specimens were 691.679N with an interquartile range of 150.9713N. The statistical analysis revealed no significant difference between and within each group (p > .05). Conclusion: Neither angulation of the screw access channel nor the size of the connection platform of Nobel conical implant affect the fracture strength of the monolithic 3Y-TZP zirconia restoration on Dynamic TIBASE® angulated screw channel abutment.
Flipped Classrom vs. Conventional Classroom: Prospective Randomized Controlled Trial of First-Year Dental Students
(2023-05-10) Sohraby, Ali; Buschang, Peter; Taylor, Reginald; Tadlock, Larry; Ruest, Bruno
Background: The implementation of the flipped classroom model in dental education offers prospective improvements for student education. Purpose: To increase understanding of differences in performance for dental students using the flipped classroom model, and examine their perceptions of the technique. Research Design: A flipped classroom approach with crossover design was implemented, splitting students into two groups. Each group used the traditional classroom approach for two lectures, and online learning modules with a flipped classroom session for the other two lectures. Performances on a quiz administered to both groups and on the final exam in the course were analyzed. Results: In the short-term (quiz evaluation) and long-term (final evaluation), no significant difference was found between flipped and traditional groups. Students reported an overall preference for the flipped classroom model. Conclusions: Student performance with the flipped classroom model was as good as traditional lecture performance, but students report more effective use of their time and better learning opportunities. The flipped classroom time itself could be further improved to increase interactivity and improve learning outcomes.
Investigating the Role of Antioxidant Gel (AO) on Wound Healing: An In Vivo Study
(2023-05-10) Ukaegbu, Kelechi Elizabeth; Regan, Deborah; Plemons, Jacqueline; Luan, Xianghong; Schneiderman, Emet; Svoboda, Kathy
Prolonged inflammation and oxidative stress are deleterious to periodontal healing. Anti-inflammatory and antioxidant agents have increasingly been researched and used to promote efficient healing. This in vivo study compared the effects of Periosciences antioxidant gel (AO) on wound healing following gingival augmentation with acellular dermal matrix (Alloderm™) to the gold standard, Chlorhexidine mouth rinse (CHX) and untreated control. Methods and materials One investigator subjected Sixty Sprague Dawley rats to the same IACUC-approved surgical procedure. Envelope flaps were created in the lower incisor region, and AllodermTM was inserted. Sutures were used to close the surgical site. Rats were randomly assigned to receive the application of AO or 0.12% CHX to the surgical site twice daily. The control group had no agent applied. Animals were assessed twenty-four and seventy-two hours following surgery, and weights were recorded pre and post-surgery for all animals. Surgery site tissues for histological analysis and real-time polymerase chain reaction (RT-PCR) were obtained to quantify the gene expression of interleukin 1 (ILl ), tumor necrosis factor-alpha (TNFa), myeloperoxidase (MPO) and superoxide dismutase (SOD). A double-blind analysis of soft tissue healing based on randomized clinical photos was completed. Normally distributed data was analyzed by ANOVA followed by Bonferroni posthoc testing. For non-normally distributed data, Kruskal Wallis and Mann Whitney tests were used. Results Based on a double-blind clinical assessment, rats in the AO group scored significantly better than those in the CHX and control groups when comparing gingival color, granulation tissue, swelling and graft exposure (p<0.05). However, the degree of epithelization was inconclusive. All rats lost weight in the first twenty-four hours following surgery. Rats treated with AO and CHX regained significantly more weight at seventy-two hours than control rats (p= 0.04 and 0.009, respectively). TNFa expression was significantly higher in the AO group compared to CHX (p=0.027) and controls (p=0.018) at twenty-four hours. The AO group also had significantly higher levels of antioxidant enzyme (SOD) expression in the first twenty-four hours compared to CHX (p= 0.021). Discussion This randomized-control in vivo study demonstrated that applying topical agent AO or CHX led to less post-operative pain in rodents, based on their weight recovery at seventy-two hours. Image analysis indicated that animals treated with AO had less swelling and healed faster than CHX and control treated animals. Despite significantly increasing pro-inflammatory marker TNFa, the antioxidant enzyme SOD was expressed to counteract oxidative stress and reduce inflammation in the AO-treated rats. An increase in SOD was not apparent in the CHX group; it is known that this agent inhibits fibroblasts, a source of SOD. Therefore, the rats in the CHX group had overt inflammation and reduced antioxidant defense. Conclusions Topical agents appear to be beneficial to soft tissue healing and post-operative comfort. Rats treated with AO show earlier signs of recovery and less inflammation than those treated with CHX and control. We postulate that AO promoted an earlier inflammatory process while counteracting oxidative stress with increasing antioxidant mechanisms such as enzyme SOD.
Expansion in Adults: A Novel Protocol
(2023-05-02) Yeh, Debbie Tyan; Buschang, Peter H; Tadlock, Larry; Taylor, Reginald; Opperman, Lynne
Purpose To evaluate and compare the skeletal and dentoalveolar effects produced by two maxillary expansion protocols in skeletally mature, non-growing adults. Materials and Methods The study sample included 40 (15 female, 25 male) treated subjects with an average age of 32.4 ± 12.2 years at initial records (T0). All subjects were treated by two practitioners in a private practice setting. Upon recruitment, subjects were placed into three different surgical expansion groups, initially based on sex and age. Preoperative CBCT scans acquired at the initial appointment were utilized to further classify treatment groups based on radiographic modifiers. The two protocols, Type II and Type III, used the same micro-implant skeletal expander type-2 design (MSE-2, Great Lakes Orthodontics). Type II protocol consisted of an expander with four bi-cortical micro-implant screws, midline corticopunctures approximately 2 mm apart, and a vertical midline osteotomy. Type III protocol consisted of Type II protocol in adjunct with horizontal anterior maxillary osteotomies. Following adequate expansion and prior to appliance removal, post-expansion CBCT scans were acquired for T1 records. The average time difference between pre- and post-expansion scans was 0.6 ± 0.5 years. The scans were evaluated to determine the skeletal and dentoalveolar changes. Results Type II and Type III protocols showed significant increase from pre- to post-expansion for all variables except IOW. Anteriorly, AABW, AABWI, and AAPW showed significantly greater changes in Type III compared to Type II. Posteriorly, there were no significant differences between the changes. Dentally, ICW showed significantly more changes in Type III than Type II; however, the difference in changes at IMW was not significant. Conclusions Type II and Type III protocols are equally effective and successful at achieving expansion in the posterior region. Type III protocol can produce more significant expansion in the anterior region than Type II protocol; however, significant anterior changes, especially at ICW, are not usually desired for orthodontic purposes. This suggests that the less invasive Type II protocol is sufficient in producing significant changes in the region of interest for maxillary deficient skeletally mature, non-growing individuals.
Treatment of Carious White Spot Lesions with MI Paste Plus, with or without One-Time Microabrasion: A Split-Mouth, Randomized Clinical Trial
(2023-04-27) Lammert, Kayla Michelle; Jing, Yan; Buschang, Peter; Glenn, Gayle; Noureldin, Amal
The purpose of this study was to determine whether the use of microabrasion with MI Paste Plus™ (GC America) provided a significant benefit in reducing carious White Spot Lesion (WSL) surface area compared to using MI Paste Plus alone. This prospective, randomized, split-mouth clinical trial involved 13 patients recruited from Texas A&M School of Dentistry, Department of Orthodontics. Patients completed fixed orthodontic treatment at least six months prior to the study and had at least one carious white spot lesion on both the right and left maxillary anterior dentition. Teeth were randomized into a treatment group (n=27) and a control group (n=28). The treatment group, isolated from the control group via rubber dam, underwent one session of microabrasion using Opalustre™ (Ultradent Products, Inc., South Jordan, Utah) applied for 60 seconds, rinsed, and repeated for a maximum of eight minutes. Both groups used MI Paste Plus applied twice daily for five minutes for six weeks. Surface areas of the WSLs were quantified using standardized photography and software analysis. WSL size as a percentage of labial tooth surface area decreased significantly for both the treatment and control groups, decreasing by 1.79% in the control group and 9.77% in the treatment group. WSL size decreased significantly compared to initial lesion size for both treatment and control groups. Compared to initial lesion size, WSLs in the control group decreased by 10.85%, and lesions in the treatment group decreased by 80.31%. Lesions treated with microabrasion and MI Paste Plus decreased significantly more compared to labial tooth surface and initial lesion size than lesions treated with MI Paste Plus alone. Microabrasion treated in one session and in conjunction with MI Paste Plus is a more effective option in the treatment of carious white spot lesions in post-orthodontic patients.
How Parents Choose an Orthodontist: A New Emphasis on Age-Old Factors
(2023-05-01) Bortnem, Eric Ardeen; Kesterke, Matthew; Buschang, Peter; Jing, Yan; Ruest, L. Bruno
The present study aims to 1) validate a survey, and 2) use the survey to evaluate the relative and absolute importance of various factors that influence parents’ decision to patronize a particular orthodontist, including an emphasis on practitioner sex and adolescent autonomy. The study sample included 86 (20 M, 66 F) adults 41.7 ± 8.0 years of age. Each respondent was a family member of a patient currently undergoing orthodontic treatment at the practice from which the responses were obtained. The study design was cross-sectional. A survey was created using Qualtrics software and distributed via QR code at 7 private orthodontic offices throughout Texas. Questions took the form of either multiple choice or rating based on the Visual Analog Scale (VAS) from 0-100 with “Not at all important” and “Extremely important” as anchors. Some questions were based on those asked in previously validated surveys from the orthodontic literature, while others were novel to the present study. Over half (55.2%) of respondents were referred to an orthodontist by their dentist, and only 30.4% of those who were referred were referred to more than one orthodontist. Multiple consults were sought by 30.5% of respondents, with the primary reasons being to find the best fit (54.8%) and comparing cost (35.5%). In total, 20.2% of parents had a preference regarding the sex of their child’s orthodontist, the majority (70.6%) of which were mothers with a preference for their daughters. The most important factors when choosing an orthodontist were Comfort (91.6), Caring Attitude (91.6), and Communication (91.6). The least important factors were Sex (22.3), Dentist Referral (62.2), and Office Location (64.1). Messages of quality, compassion, and empowerment appealed most to parents when choosing an orthodontist. Nearly a third (32.9%) indicated that their child’s opinion did (or would) heavily influence the selection of an orthodontist. Over 40% of parents would pursue a different treatment plan if their child was opposed to one presented by the orthodontist. Many parents seek consults with multiple orthodontists to find the best fit and affordability. Comfort, Caring Attitude, and Communication were the most important factors for parents when choosing an orthodontist for their child. Orthodontist sex was the least important factor and most parents do not have a preference regarding it. However, when parents do have a preference, it’s typically the mother preferring a female orthodontist for her daughter. Nearly all children have some influence in who their orthodontist will be, and many have a heavy influence in orthodontic treatment decisions, though relatively few actually express an opinion.
The Effect of Using Worn Osseodensification Drills on Bone An Ex-Vivo Study
(2023-05-10) Afouxenidis, Panagiotis; Parra, Carlos; Umorin, Mikhail; Patel, Paras
Introduction: The use of osseodensification drills to increase implant stability, and expand edentulous ridges is now considered mainstream. These drills are used in reverse to compact, and displace, instead of removing the bone. It is suggested to limit their use to 20 osteotomies, however, as the mode of function does not include cutting, the importance of maintaining drill sharpness is questionable. Materials and Methods: Bovine tibial plateau and ribs were used in this study. New, and worn drills were used to perform osteotomies and place implants. Wear protocol consisted of 15 cycles of sterilization, and 100 osteotomies half clockwise, and half counterclockwise. The primary outcome in this study was temperature increase, and secondary outcomes included the time to complete each osteotomy, bone expansion coronally, and apically, and primary implant stability measured with resonance frequency analysis. A non-inferiority study design was utilized, with preset clinically acceptable margins. (2.0°C, 4.0s, 0.2mm, 5 ISQ). The t-test was conducted for the outcome of temperature, and time-to-complete, whereas the non-parametric Wilcoxon Mann-Whitney test was used for the other outcomes. Results: Mean temperature increases were 10.81 (±2.09) for the new, and 10.96 (±2.61) for the worn drills. Mean time-to-complete was 14.44 (±5.43) and 14.33 (±5.12) for new and worn drills. Mean primary stability was 83.17 (±3.31) and 82.04 (±1.81) for the new and worn drills. For the outcome of expansion, mean expansion at the coronal portion was 0.47(±2.80) for the new drills, and 0.51 (±2.80) for the worn drills, whereas, for the apical portion was 0.43 (±0.33) and 0.30 (±0.16) for the new and worn drills respectively. Non-inferiority was established for temperatures increases (1.75, 95%CI: 0.013 – inf, p=0.049), for time-to-complete (1.91, 95%CI: 0.414 to inf, p=0.035), for primary stability (p<0.001), and for coronal expansion (p=0.034). The null hypothesis that there was no difference between groups was not rejected for the outcome of apical expansion (p=0.36) Discussion: Within the limitations of this study, the use of osseodensification drills in reverse may still be safe, and effective after repeated usage, in terms of expected temperature increases, time efficiency, primary stability achieved, and bone expansion.
The Effects of Early Biobloc Treatment on Hyperdivergent Children
(2023-05-01) Harvey, Benjamin Joseph; Buschang, Peter; Tadlock, Larry; Schneiderman, Emet; Jing, Yan
To evaluate the skeletal and dental changes produced when treating hyperdivergent children in the mixed dentition with BioBloc appliances. The study sample included 46 (16 M, 30 F) consecutively treated hyperdivergent subjects 8.2 ± 1.1 years of age at initial records. Each subject was treated with Biobloc therapy alone, which consisted of 3 phases and used 4 appliances to expand the maxillary and mandibular arches and retrain the oral posture. The expansion phase, orthopedic phase, and the 1-year retention phase lasted 4.3 ± 1.7 years. A matched, untreated control group was used to evaluate treatment effects. Lateral cephalograms were taken at the start of treatment and at the end of the retention phase to determine dental and skeletal changes. The treated group showed significant (p<.05) AP maxillomandibular corrections compared to untreated controls, resulting in a 7x greater (1.9°) reduction of the ANB angle. Pogonion and menton advanced 2.3x (3.3 mm) and 1.9x (2.6 mm) more in the treated than control group, respectively, and SNB increased 4x (1.3°) more than the controls. Treatment produced a greater 4.2 mm class II molar correction, largely due to mandibular advancement. Overjet reductions of 1.5 mm were observed in the treated group, compared to 0.6 mm increases in the controls. The gonial angle decreased significantly less (1.5°) in the treated than the control group. The Y-axis showed that mandibular growth of the treated group changed toward a more horizontal direction. Vertically, treatment produced no statistically significant skeletal or dental between-group differences. No significant changes were observed in hyoid position or hyoid angle. This preliminary study showed that Biobloc therapy produces significant improvements of AP maxillomandibular skeletal and dental relationships through anterior mandibular displacement, and changes toward a more horizontal direction of mandibular growth.
Contemporary Preferences in Lip Position of Internet Users
(2023-03-07) Togrye, Cameron Thomas; Buschang, Peter H; Kesterke, Matthew J; Tadlock, Larry P.
The primary aim of this study was to assess the preferences of Caucasian, adult internet users regarding lip protrusion and to assess if there were generational differences in those preferences. The secondary aim of this study was to gauge the relative influence various mass media had on facial esthetic preferences as well as the overall importance of facial esthetics for the different generations and to present a novel new method for presenting facial renditions in orthodontic research. A sample of 650 adult internet users who identified as “Caucasian / Middle Eastern” were asked to rank the relative attractiveness of a series of modified 3-D facial depictions. This sample had equal ratios of female: male and equal samplings from four generational groups (Gen Z, Millennials, Gen X and Baby Boomers). One male and one female Caucasian individual were used as models, and the faces were adjusted to untreated norms as a baseline. The models’ lips were then altered to be more retrusive or protrusive in 1 mm increments thereby creating 7 versions of each face ranging from -7 mm to -1 mm lower lip to E-line (LLEL) for the male subject and -5 mm to +1 mm lower lip to E-line for the female subject. Those surveyed were asked to rank the seven male and female iterations. Respondents were also asked to indicate the level influence of social media, television and print media had on their facial esthetic preferences as well as the level of importance they placed on facial esthetics in general; this was done via a Visual Analog Scale (VAS) which ranged from 0-100 with not important to very important as ends of the spectrum. Respondents as a whole ranked the more protrusive profiles more favorably than the retrusive profile; these results were significant (p<0.05) and true for both female and male facial scans. There were no significant differences between generational group rankings except for the most retrusive female face (LLEL: -5 mm) where Gen Z viewed the profile as more favorable than Gen X or Baby Boomers, and Millennials viewed the profile as more favorable than Gen X. Social media had a statistically significant higher influence on facial esthetics for the younger generations; the level of influence decreased as the generation got older. The younger generations valued facial esthetics overall more than the older groups. Protrusive lips were more favored by all respondents, regardless of age group. For both the male and female model, the most favored lip positions by those surveyed were more protrusive than untreated Caucasian norms. Age did not appear to play a significant role in judgements on the attractiveness of varying degrees of lip protrusion. Social media plays a larger role in shaping the facial preferences of younger generations and these younger groups also appear to value facial esthetics more than older ones.
The Role of Din in Murine Bone and Tooth Development
(2022-12-13) Lamichhane, Bikash; Wang, Xiaofang; Svoboda, Kathy K.; Ruest, L. Bruno; Wang, Fengming
Bone- and tooth-related disorders are a major health burden in modern society. Identifying the cellular and molecular mechanisms of such disorders hold great potential in the development of novel therapeutic strategies. Recent genetic studies in mice have associated a peculiar tooth phenotype, “dense incisors (Din)” featuring overgrowth of dentin and arrested growth of incisors, with a predicted gene 4930453N24Rik (human ortholog C3orf38): Din. The spontaneous Din mutant mice showed smaller bodies and crania suggesting Din is a novel gene that has pivotal roles in bone and tooth development. LacZ-Knockin Din knockout (KO) allele and Din-flox mouse models were generated to study the cellular and molecular mechanisms associated with Din. The Din-KO mice completely recapitulated the phenotypes of spontaneous Din mutant mice. These phenotypes strongly suggested that Din may have critical roles in the homeostasis of osteogenic and odontogenic stem cells. Gene expression patterns, reverse genetics, bioinformatics analyses of in-house and open-access single RNA sequencing (scRNAseq) data, and double RNAScope colocalization experiments collectively revealed that Din functions in the skeletal and dental MSCs. Din was extensively expressed by multiple MSC subsets but only a portion of cells in each subset expressed Din. Din expression was indispensable for the homeostasis of MSCs. Thus, Din deficiency led to defective homeostasis of bone, suture, and tooth MSCs during postnatal growth and injury repair. Bioinformatic, transcriptomic, proteomic, and G-LISA assays were performed which revealed that Din plays a key role in governing the homeostasis of MSCs by interacting with small GTPases. Din was an immediate input regulator of small GTPases: RhoA and Rac1. Moreover, Din-KO mice had severely impaired osteogenesis and increased adipogenesis both in vivo and in vitro which highly suggested dysregulated Wnt signaling. The Wnt signaling changes were tested in Din-KO tissues through immunohistochemistry of Wnt signaling mediators: β-catenin, Lef1, Tcf1, and Cyclin D1. Also, a classical lithium chloride (LiCl) stimulation assay was performed on Din-KO BMSCs (in vitro) compared with their WT counterparts. Both analyses confirmed dysregulated Wnt signaling in Din-KO mice. Thus, we concluded that Din-GTPase interactions regulate Wnt signaling in the homeostasis of bone, suture, and tooth MSCs.
Roles of Inositol-Requiring Enzyme 1 Alpha (IRE1α) in Odontogenesis
(2022-07-26) Xu, Qian; Lu, Yongbo; Qin, Chunlin; Ruest, L. Bruno; Kramer, Phillip; Luan, Xianghong
Dentin sialophosphoprotein (DSPP) is highly expressed in odontoblasts that form dentin, and mutations in the DSPP gene are associated with dentinogenesis imperfecta (DGI)/dentin dysplasia (DD), which are the most common inherited dentin disorders. However, the molecular pathogenesis of mutant DSPP in DGI is largely unknown. As the most conserved endoplasmic reticulum (ER) stress sensor, the inositol-requiring enzyme 1α (IRE1α) pathway plays important roles in the pathophysiological processes and has profound effects on disease progression and prognosis. IRE1α deals with ER stress by unconventional splicing of x-box binding protein 1 (XBP1) mRNA, or regulated IRE1-dependent decay (RIDD). Previously, we established a DSPP-KI (knock-in) mouse model with the P19L mutation in its DSPP gene, which resembled the features of human DGI patients. We found out that the IRE1α pathway was highly activated in the dental pulp cells of the Dspp-P19L mutant mice. The goal of this study was to determine the pathophysiological roles of IRE1α in dentin formation. We generated and characterized the transgenic mice with Ire1α specifically deleted in the odontoblasts in the wild-type and Dspp-P19L mutant mice. Compared to wild-type control, the odontoblast-specific Ire1α conditional knock-out (cKO) mice (2.3 Col1-Cre;Ire1fl/fl) exhibited enlarged dental pulp chamber and thinner pulp chamber roof dentin. After Ire1α deletion in the odontoblasts of Dspp-P19L mutant control, the compound mutant mice (2.3 Col1-Cre;Ire1fl/fl;DsppP19L/+) displayed much larger dental pulp chamber and thinner roof dentin. A reduction in DSPP mRNA level and an increased intracellular retention of DSPP protein in the odontoblasts were also observed in 2.3 Col1-Cre;Ire1fl/fl;DsppP19L/+ mice. Odontoblast-specific inactivation of Ire1α did not rescue the reduced DSPP mRNA level in the odontoblasts of Dspp-P19L mutant mice, excluding the roles of RIDD in degrading DSPP mRNA in Dspp-P19L mutant mice. Then we generated and characterized the transgenic mice that constitutively expressed spliced XBP1 (XBP1S) in the odontoblasts. The Twist2-Cre;Xbp1CS/+ mice displayed significantly reduced dentin formation and exhibited remarkably increased XBP1S protein expression in the dental pulps. In summary, our results showed that: 1) IRE1α was required for normal dentin formation; 2) the IRE1α-XBP1 pathway, but not RIDD, was involved in DGI associated with mutant DSPP-P19L protein.
Analysis and Quantification of Orbital Fractures: An Artificial Intelligence-Based Approach
(2022-07-29) Bhattacharjee, Ritesh; Kesterke, Matthew J; Sankaranarayanan, Ganesh; Reddy, Likith V; Read-Fuller, Andrew; Nair, Madhu K
Trauma to the orbital region accounts approximately for 3% of all craniofacial injuries, with a mean hospitalization cost of US$ 35,500 per case. Management of orbital fractures is challenging as a substantial amount of individual judgment is required to determine the need for surgery. The definitive indications for surgery include muscle entrapment, visible enophthalmos (sunken eye), diplopia (double vision) or hypo-globus (vertical asymmetry of the globes). Otherwise, the need for surgery is based on subjective factors such as the relative size of the fracture, which is used as a proxy for the risk of developing enophthalmos once healing has progressed. Other factors considered include calculating the change in orbital volume, presence, and extent of tissue herniation, etc. However, these methodologies lack robust sample sizes or controls for population-based variation. In addition, sophisticated systems to standardize orbital fracture surgical intervention are impractical for real-time clinical application and have low reproducibility and not adequately validated against clinical outcomes. In essence, complications arising from untreated orbital fractures pose a unique predictive analytics problem, and the need for an effective and informed risk assessment tool to help determine the need for surgical intervention is highly desired. Analytics utilizing Artificial Intelligence (AI) provides a unique opportunity to address this issue. An innovative AI-based system was be developed to and classify orbital fractures at risk of future complications without surgery. Ultimately the analytical tools developed through this project will be used to develop predictive tools to link fracture characteristics with the likelihood of developing poor clinical outcomes like enophthalmos, hypoglobus and late-stage diplopia. This novel AI approach seeks to resemble the decision-making process of a cranio-maxillofacial surgeon by automatically classifying demographic, clinical, radiographic and morphological data from patients and their injury characteristics. This study will provide a proof-of-concept framework in AI-based computational modeling for assessment of outcomes for craniofacial trauma.
Tendon Cells Root into Rather Than Attach to the Humerus Bone Head via Enthesis Fibrocartilage.
(2022-07-11) Wang, Zheng; Jing, Yan; Svoboda, Kathy; Benson, Douglas; Wang, Xiaofang; Ruest, Louisbruno
Large joints are composed of two closely linked cartilages: articular cartilage (AC) and enthesis fibrocartilage (EF). For many years, both cartilages were thought formed by chondrocytes, whereas tendon, which attaches to the humerus head, is largely considered as a completely different connective tissue. In this study, we raised an unconventional hypothesis: tendon cells directly form EF via cell transdifferentiation. To test this hypothesis, we first qualitatively and quantitatively demonstrated distinctions between AC and EF using comprehensive approaches. Next, we traced the fate of tendon cells using ScxLin (a tendon specific Cre ScleraxisCreERT2; R26R-tdTomato line) with one-time tamoxifen induction at early (P3) or young adult (P28) stages and harvested mice at different development ages, respectively. Our early tracing data revealed different growth events in tendon and EF: an initial increase but gradual decrease in the ScxLin tendon cells and a continuous expansion in the ScxLin EF cells. The young adult tracing data demonstrated continuous recruitment of ScxLin cells into EF expansion during P28 and P56. A separate tracing line, 3.2 Col1Lin (a so-called "bone-specific" line), further confirmed the direct contribution of tendon cells for EF cell formation, which occurred in days but EF ECM maturation (including high levels of SOST, a potent Wnt signaling inhibitor) took weeks. Finally, loss of function data using diphtheria toxin fragment A (DTA) in ScxLin cells demonstrated a significant reduction of ScxLin cells in both tendons and EF cells, whereas the gain of function study (by stabilizing β-catenin in ScxLin tendon cells via one-time injection of tamoxifen at P3 and harvesting at P60) displayed great expansion of both ScxLin tendon and EF mass. Together, the studies demonstrated that fibrocartilage is an invaded enthesis likely originating from tendon via a quick cell transdifferentiation mechanism with a lengthy ECM maturation process. The postnatally formed fibrocartilage roots into existing cartilage and firmly connects tendon and bone instead of acting as a simple attachment site as widely believed. We anticipate this study to stimulate more intense exploring in this understudied area, especially for patients with enthesopathy and sporting injuries.

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