Facile Synthesis of Well‐Defined Telechelic Alkyne‐Terminated Polystyrene in Polar Media Using ATRP With Mixed Fe/Cu Transition Metal Catalyst

The synthesis of polystyrene (PS) by atom transfer radical polymerization using the Fe(0)/CuBr₂ catalytic system in dimethylformamide is reported. The effects of temperature, ligand, initiator structure, and monomer to solvent ratio on the polymerization kinetics are evaluated. PS with high molecular weight, low polydispersity, and telechelic structure are achieved and successfully used for further reinitiation or the copper(I)‐catalyzed Huisgen 1,3‐dipolar cycloaddition click reaction between alkyne‐ and azide‐terminated PS. For the first time, suitable styrene polymerization rates are achieved using this cost‐effective and environmentally attractive catalytic system. This method can be very useful in macromolecular engineering to afford PS‐based materials with well‐controlled structure.     

Clinical performance of short versus standard dental implants in vertically augmented bone: an overview of systematic reviews

Objective

To answer the question: What do we know so far about the clinical performance of short implants (≤ 7 mm) when compared to standard length implants in vertically augmented bone, as well as which is the overall confidence of the systematic reviews (SRs) about this topic?

Materials and methods

An overview of SRs was conducted. The searches were performed in six electronic databases and grey literature. SRs about short (≤ 7 mm) versus standard dental implants performance in vertically augmented bone were included. The assessed outcomes were marginal bone loss (MBL), implant survival (IS), prosthetic (PC) and biological complications (BC), costs, surgical time, and patient satisfaction. AMSTAR 2 was used to evaluate the overall confidence of included SRs.

Results

Thirteen SRs were included. Nine of twelve SRs reported a lower MBL for the short implant group. All the included SRs showed no difference in the IS between groups. A higher rate of BC was reported for standard-length implants in four out of five SRs. No differences regarding PC were reported in four of five SRs. Information related to patient preference, cost, and surgery time were underreported. The confidence evaluation of the SRs was stratified as low for five SRs and critically low for eight SRs.

Conclusions

In an overall low-to-very low confidence levels, short implants appear to perform better in the mid-term (up to 5 years) than standard dental implants associated with vertical bone augmentation regarding MBL and BC, but they have a similar performance regarding IS rates and PC. There is an imperative need to improve the methodological quality of SRs, and efforts should focus on conducting RCTs to broaden the knowledge on this topic.

Clinical relevance

Short implants could represent a viable, simpler, and less invasive treatment when available bone height is limited.

     

Detection of cytokeratins in ghost cells of calcifying cystic odontogenic tumor indicates an altered keratinization and hair follicle differentiation for their development

Calcifying cystic odontogenic tumors (CCOTs) are benign cystic lesions of odontogenic origin characterized by an ameloblastoma-like epithelium and the presence of a group of cells named ghost cells. The pattern of cytokeratin (Ck) expression on these lesions remains unclear and needs to be clarified. To this end, the expression of Ck6, Ck13, Ck14, Ck18, and Ck19 in the epithelium lining of 7 cases of CCOTs was evaluated by immunohistochemistry. For this, the epithelium lining was divided into 3 distinct regions: basal layer, suprabasal layer, and the compartment composed of ghost cells. In this study, 6 cases (85.7%) were classified as type 1 and 1 (14.3%) as type 4. All cases were negative for Ck13 and Ck18, despite the epithelial layer, as well as in the ghost cells. Ck6 was only positive in the ghost cells. Positivity for Ck14 and Ck19 was found in the basal and suprabasal layers, including the ghost cells. The results showing positivity for Ck14 and Ck19 in all of the analyzed cases reinforce CCOT as being of odontogenic origin, and the restricted expression of Ck6 in the ghost cells may be indicative that these cells suffer an altered differentiation into hair follicles in CCOTs.     

Exenatide and Sitagliptin Decrease Interleukin 1β, Matrix Metalloproteinase 9, and Nitric Oxide Synthase 2 Gene Expression But Does Not Reduce Alveolar Bone Loss in Rats With Periodontitis

Background: New drugs for the treatment of diabetes, glucagon‐like peptide‐1 (GLP‐1) receptor agonists and inhibitors of dipeptidyl peptidase‐4 (DPP‐4) have shown pleiotropic effects on bone metabolism and anti‐inflammatory properties. The aim of this study is to evaluate the effects of exenatide (GLP‐1 agonist) and sitagliptin (DPP‐4 inhibitor) during periodontitis induction by ligature insertion in rats. Methods: Forty rats were divided into four groups: 1) animals with induced periodontitis that received exenatide (EG); 2) animals with induced periodontitis that received sitagliptin (SG); 3) animals with induced periodontitis and without drug treatment (LG); and 4) animals without induced periodontitis and without drug treatment (controls). The drugs were administered for 28 days. On the day the animals were sacrificed, blood was collected for analysis of glucose and DPP‐4 levels. The gene expressions of prostaglandin‐endoperoxide synthase 2, tissue inhibitor of metalloproteinase 1, Dpp4, nitric oxide synthase 2 (Nos2), interleukin 1β (Il1b), and matrix metalloproteinase 9 (Mmp9) in the gingiva; support and alveolar bone loss; connective tissue attachment; and the quantity of gingival collagen were evaluated. Results: Exenatide and sitagliptin treatments have led to a lower percentage of weight gain but did not influence glycemia. Sitagliptin reduced the serum concentration of DPP‐4. Interestingly, although the gene expression profile has revealed a downregulation of Mmp9, Nos2, and Il1b in both EG and SG compared to LG, a significant protective effect was not observed on alveolar bone and collagen tissue in this model. Conclusion: Regardless of the reduction of the expression of Il1b, Nos2, and Mmp9, the drugs were not effective in the stabilization or reduction of alveolar bone loss and collagen degradation in rats.     

The Value of Indirect Teaching Strategies in Enhancing Student-Coaches’ Learning Engagement

This study aimed to examine the indirect teaching strategies adopted by a coach educator in terms of promoting student-coaches’ engagement in a positive and active learning environment. The participants were an expert coach educator and seven student-coaches from an academic coaching setting. A mix method approach was used to collect data. Whilst video-recording and participant observations were used to collect data from the lessons, focus groups were adopted to recall the perceptions of student-coaches. The results showed that indirect teaching strategies (i.e., asking questions, showing signs of autonomy by monitoring the pace at which they completed tasks and actively engaging in the search for solutions to tasks) implemented by the coach educator promoted a supportive and challenging learning environment which, in turn, encouraged student-coaches to be more actively involved in the lessons. Additionally, the affective aspects of the relationship established with student-coaches (tone of voice, gestures, facial expressions, eye contact, physical contact and humor) led them to feel confident in exposing their doubts and opinions, and in learning in a more autonomous manner. Moreover, the practical lessons proved to be crucial in helping student-coaches to reach broader and deeper forms of understanding by allowing the application of theory to coaching practice. In conclusion, this study reinforces the value of indirect teaching strategies to stimulate an active learning environment. It further highlights the value of practical learning environments to better prepare neophyte coaches for dealing with the complex and dynamic nature of their professional reality.

Key points

• Both instructional and affective teaching indirect strategies used by the coach educator promoted a positive and challenging learning environment to student-coaches.
• The directness profile used by this coach educator (questioning, giving autonomy for problem solving and responsibility to regulate the learning tasks development) promoted the awareness and the ability of student-coaches to explore alternative solutions and self-regulate their own learning.
• Using humor, touch, gestures and tone of voice, the coach educator showed great care for student-coaches, which impacted positively on their enthusiasm, confidence and desire to be actively engaged in their own learning.

Key words: Coaching, coach education, teaching approach, learning     

Primary headaches interfere with the efficacy of temporomandibular disorders management

OBJECTIVES:

This cross-sectional study aimed to evaluate the influence of Primary Headache (PH) on efficacy of a Temporomandibular Disorders (TMD) conservative therapy and its association with the presence of self-reported parafunctional habits.

SAMPLE AND METHODS:

Sample was composed of 400 medical records, divided into four groups: I) Muscular TMD (n=64); II) Muscular TMD+PH (n=48); III) Muscular TMD+Articular TMD (n=173); IV) Muscular TMD+Articular TMD+PH (n=115). All groups had undergone a TMD therapy for three months with a stabilization appliance and counseling for habits and behavioral changes, with no specific headache management. Current pain intensity and existence or not of self-reported bruxism were assessed. Repeated measures ANOVA and Chi-Square test followed by Odds were used for statistical analysis, with a significance level of 5%.

RESULTS:

results of this study showed that: (1) A conservative therapy with stabilization appliance and counseling for habits and behavioral changes was effective in the TMD pain relief; (2) Groups with an additional diagnosis of PH had worsened the pain improvement significantly; and (3) no association between the presence of self-reported bruxism and PH was found.

CONCLUSIONS:

this study could elucidate the important effect that headache may have on the TMD management.     

Metallothionein immunoexpression in non-syndromic and syndromic keratocystic odontogenic tumour

Background

To compare the metallothionein (MT) immunoexpression in non-syndromic and syndromic keratocystic odontogenic tumour (KOT), to correlate MT with cellular proliferation, and to evaluate the influence of inflammation in MT.

Material and Methods

Fourteen cases of KOT were submitted to immunohistochemistry for MT and Ki-67 analysis. The lesions were grouped according to their grade of inflammation, and statistical analysis was performed.

Results

MT was higher in non-syndromic KOT than in syndromic KOT (p<0.05). No statistical difference in Ki-67 could be identified; however, an inverse correlation was observed between MT and Ki-67 in both lesions. When analysing inflammation, non-syndromic KOT showed no differences in either MT or Ki-67.

Conclusions

The MT immunophenotype of syndromic KOT was different from non-syndromic KOT. MT might not be involved in the proliferation control of both KOT. MT and Ki-67 immunoexpressions proved to be unaffected by inflammation in non-syndromic KOT. Key words: Odontogenic tumours, basal cell nevus syndrome, metallothionein, Ki-67 Antigen, immunohistoche-mistry.