Deletion of the Transcription Factor PGC-1α in Mice Negatively Regulates Bone Mass.

Peroxisome proliferator-activated receptor-gamma coactivator (PGC1α) is a transcription coactivator that interacts with a broad range of transcription factors involved in several biological responses. Here, we show that PGC1α plays a role in skeletal homeostasis since aged PGC1α-deficient mice (PGC1α-/-) display impaired bone structure. Micro-CT of the tibial mid-shaft showed a marked decrease of cortical thickness in PGC1α-/- (- 11.9%, p < 0.05) mice compared to wild-type littermate. Trabecular bone was also impaired in knock out mice which displayed lower trabecular thickness (Tb.Th) (- 5.9% vs PGC1α+/+, p < 0.05), whereas trabecular number (Tb.N) was higher than wild-type mice (+ 72% vs PGC1α+/+, p < 0.05), thus resulting in increased (+ 31.7% vs PGC1α+/+, p < 0.05) degree of anisotropy (DA), despite unchanged bone volume fraction (BV/TV). Notably, these impairments of cortical and trabecular bone led to a dramatic ~ 48.4% decrease in bending strength (p < 0.01). These changes in PGC1α-/- mice were paralleled by a significant increase in osteoclast number at the cortical bone surface and in serum level of the bone resorption marker, namely, C-terminal cross-linked telopeptides of type I collagen (CTX-I). We also found that in cortical bone, there was lower expression of mRNA codifying for the key bone-building protein Osteocalcin (Ocn). Interestingly, Collagen I mRNA expression was reduced in mesenchymal stem cells from bone marrow of PGC1α-/-, thus indicating that differentiation of osteoblast lineage is downregulated. Overall, results presented herein suggest that PGC1α may play a key role in bone metabolism.

Comprehensive clinical and histological evaluation of bovine hydroxyapatite bone graft with polypropylene membrane versus leukocyte- and platelet-rich fibrin for alveolar preservation after tooth extraction.

BACKGROUND: Osseointegrated implant placement in the ideal prosthetic position necessitates a sufficient residual alveolar ridge. Tooth extraction and the subsequent healing process often lead to bony deformities, characterized by a reduction in alveolar ridge height and width, resulting in unfavorable ridge architecture for dental implant placement. Several materials, including allografts, alloplastics, xenografts, and autogenous bone, are commonly used to address these concerns. In this context, leucocyte- and platelet-rich fibrin (L-PRF) emerges as a promising solution. METHODS: This case report aims to compare the clinical and histological efficacy of bovine hydroxyapatite bone graft covered with polypropylene membrane (BHAG-PM) and leucocyte- and platelet-rich fibrin (L-PRF) in preserving dental alveoli following tooth extraction. Extraction, graft placement in the alveoli, and the anterior border between extracted elements were performed for both treatment groups. RESULTS: Up to 24 months of follow-up revealed satisfactory and comparable clinical and histological outcomes. These results suggest that both BHAG-PM and L-PRF effectively promote alveolar preservation, paving the way for ideal implant placement. CONCLUSIONS: In general, bone-substitute materials are effective in reducing alveolar changes after tooth extraction. Xenograft materials should be considered as among the best of the available grafting materials for alveolar preservation after tooth extraction. Both techniques effectively preserve the alveolar bone and facilitate the placement of osseointegrated implants in ideal positions, paving the way for successful oral rehabilitation.

Effect of Different Surface Treatments on the Shear Bond Strength of Metal Orthodontic Brackets Bonded to CAD/CAM Provisional Crowns.

BACKGROUND: The aim of this study was to find the best surface treatment for CAD/CAM provisional crowns allowing the optimal bond strength of metal brackets. METHODS: The sample consists of 30 lower bicuspids and 180 provisional crowns. The provisional crowns were randomly divided into six different groups. Orthophosphoric acid etching (37%) was applied to 30 lower bicuspids. The provisional crowns had undergone different surface treatments. Group 1: No treatment (Control Group). Group 2: Diamond bur. Group 3: Sandblasting. Group 4: Plastic Conditioner. Group 5: Diamond bur and Plastic Conditioner. Group 6: Sandblasting and Plastic Conditioner. The brackets in all groups were identically placed using Transbond XT® Primer and Transbond XT® Paste. Then, the entire sample underwent an artificial aging procedure, and a measurement of the bond strength was conducted. After debonding, the surface of the crowns was examined to determine the quantity of the adhesive remnant. RESULTS: Bonding to natural crowns recorded the highest average, followed by the averages of groups 5 and 6. However, group 1 recorded the lowest average. Groups 2 and 4 had very close averages, as well as groups 5 and 6. A statistically significant difference between the averages of all groups was recorded (p < 0.001) except for groups 2 and 4 (p = 0.965) on the one hand, and groups 5 and 6 (p = 0.941) on the other hand. DISCUSSION: The bonding of brackets on provisional crowns is considered a delicate clinical procedure. In fact, unlike natural crowns, the orthophosphoric acid usually used does not have any effect on the surface of provisional crowns. CONCLUSIONS: Using a diamond bur combined with the plastic conditioner and sandblasting combined with that same product resulted in a bond strength close to natural crown.

Innovative Application of Diathermy in Orthodontics: A Case Report.

INTRODUCTION: Several strategies have been proposed in the literature to accelerate tooth movement, many of which are invasive and have numerous side effects, such as surgical techniques (corticotomy and piezocision technique). This research investigates to what extent diathermy can accelerate the orthodontic alignment phase. MATERIALS AND METHODS: A patient with lower teeth crowding index of the same magnitude was selected. The orthodontic treatment with Nickel-Titanium (NiTi) thermal arc 0.015 in the lower arch was performed, associated with a weekly application of diathermy using the intraoral handpiece. The total duration of treatment was three weeks. During each session, an intraoral transducer was employed to stimulate the hard and soft tissues of the left dental hemiarch, which was also orthodontically aligned like the right one. RESULTS: Comparing the tooth movements of four elements of the two hemiarchies, it was found that, overall, the two teeth examined on the treated side underwent a more significant number of changes than on the untreated side, although not by a significant amount. CONCLUSIONS: The use of diathermy, according to the authors, is a non-invasive approach that may speed up the orthodontic alignment phase and reduce treatment duration, resulting in a lower risk of caries, gingival recessions, root resorptions, and patient compliance improvement, without side effects. Further studies and an adequate sample size will be needed to confirm the findings.

Education Technology in Orthodontics and Paediatric Dentistry during the COVID-19 Pandemic: A Systematic Review.

Over the last decade, medical education changed from traditional teaching methods to telematic and networking scholar and e-learning approach. The objective of the present systematic review was to evaluate the effectiveness and teachers/student's acceptability of e-learning applied to the field of orthodontics and paediatric dentistry. A database search of the literature was conducted on PubMed and Embase databases from January 2005 to May 2021. A total of 172 articles were identified by the electronic search, while a total of 32 papers were selected for qualitative analysis. Overall, 19 articles investigated the effectiveness of e-learning, and no difference of acceptability was reported between e-learning and traditional methods for a wide part of the articles selected. A total of 25 papers provided a satisfaction questionnaire for learners and all were positive in their attitude towards e-learning. The results showed that e-learning is an effective method of instruction, complementing the traditional teaching methods, and learners had a positive attitude and perception. The evidence of the present study reported a high level of acceptability and knowledge level of e-learning techniques, compared to frontal lecture methods, in the fields of orthodontics and paediatric dentistry.

Personalized orthodontic bracket height in relation to marginal ridges.

Correct bracket placement should level both the marginal ridges and the occlusional plane. The authors describe the laboratory and clinical procedures of placing brackets in relation to the marginal ridge. The ray set is a device that allows each tooth to be dealt with an individual unit, virtually isolating it from the rest of the arch and analyzing its position in a 3-dimensional control system that determines the first-, second-, and third-order values, which the clinician needs or which must be written into the slots. The ray set makes it possible to develop and simplify bracket placement methods without a preliminary set-up, while taking an accurate reading of the marginal ridge to establish the height of slots. This procedure can be used with all multibracket techniques (vestibular and lingual) aiming to properly level the occlusal plane, thereby ensuring the correct final occlusion.

Sclerostin stimulates angiogenesis in human endothelial cells.

Sclerostin, negative regulator of bone formation, has been originally known as an osteocyte product. Recently, it has been also detected in hypertrophic chondrocytes, distinctive cells of avascular cartilage which is invaded by capillaries and then replaced by vascularized bone. Thus, we hypothesized that sclerostin, in addition to its role already known, may exert an angiogenic activity. We first proved that sclerostin increased the proliferation of human umbilical vein endothelial cells (HUVECs), and next, by using the chicken chorioallantoic membrane (CAM) in vivo assay, we demonstrated that it exerts an angiogenic activity similar to that of vascular endothelial growth factor (VEGF). This last finding was reinforced by several in vitro approaches. Indeed, we showed that sclerostin induced the formation of a network of anastomosing tubules, a significant increase in the percentage of tubule number, total tubule length and number of junctions, as well as the ability of sclerostin-stimulated HUVECs to organize capillary-like structures and closed-meshes similar to VEGF. The angiogenic response elicited by the protein may be due to the binding to its receptor, LRP6, which is highly expressed at mRNA and protein levels by sclerostin treated HUVECs and through the production of two well-known pro-angiogenic cytokines, VEGF and placental growth factor (PlGF). Finally, we demonstrated that sclerostin was also responsible for the recruitment of osteoclasts and their circulating monocyte progenitors. Overall, these findings showed for the first time the new angiogenic in vitro role of sclerostin which could be also considered as a novel molecule in angiogenesis-osteogenesis coupling.

Intentional dental reimplantation: a case report.

It is well known dental reimplantation is indicated following traumatic avulsion by the preservation of cellular vitality in the periodontal ligament and under conditions of asepsis. The rate of endodontic success at five years reported in the literature ranges between 70% and 91%. However, intentional dental reimplantation is an effective strategy for the treatment of teeth that would be difficult, if not impossible, to treat using traditional root canal therapy. Different prognoses exist for intentional dental reimplantation and trauma-related reimplantation. This is due to such important variables such as the level of cellular vitality in the periodontal ligament; the degree of trauma to surrounding tissues, and the degree of asepsis when a tooth is removed. Surgical extraction is more favorable in this regard compared to a traumatic avulsion scenario. This paper presents a report of an intentional dental reimplantation of a maxillary right first molar.

Orthodontic surgery and professional liability: the homozygote twin case.

A professional liability lawsuit of an orthodontic case is presented through its medico-legal assessment. The patient underwent an orthodontic treatment combined with several maxillo-facial surgical interventions. Several temporomandibular joint complications followed, plus he was unhappy with aesthetic results and modifications to his facial features. He wanted to verify from a medico-legal point of view the treatment received as he believed something was not done lege artis. The result of the orthodontic assessment was that there were no indications for such surgical interventions, along with other professional negligence: no psychological support given and no indications as to the aesthetic results postsurgery. It was decided to carry out an orthodontic assessment also on his homozygote twin brother, who was discovered to have the same malocclusion. His medico-legal assessment did not substitute the evidence obtained from the deceased, but gave added weight to the final technical conclusion.