Treatment outcome with orthodontic aligners and fixed appliances: a systematic review with meta-analyses

Background: The use of orthodontic aligners to treat a variety of malocclusions has seen considerable increase in the last years, yet evidence about their efficacy and adverse effects relative to conventional fixed orthodontic appliances remains unclear. Objective: This systematic review assesses the efficacy of aligners and fixed appliances for comprehensive orthodontic treatment. Search methods: Eight databases were searched without limitations in April 2019. Selection criteria: Randomized or matched non-randomized studies. Data collection and analysis: Study selection, data extraction, and risk of bias assessment was done independently in triplicate. Random-effects meta-analyses of mean differences (MDs) or relative risks (RRs) with their 95% confidence intervals (CIs) were conducted, followed by sensitivity analyses, and the GRADE analysis of the evidence quality.Results: A total of 11 studies (4 randomized/7 non-randomized) were included comparing aligners with braces (887 patients; mean age 28.0 years; 33% male). Moderate quality evidence indicated that treatment with orthodontic aligners is associated with worse occlusal outcome with the American Board of Orthodontics Objective Grading System (3 studies; MD = 9.9; 95% CI = 3.6-16.2) and more patients with unacceptable results (3 studies; RR = 1.6; 95% CI = 1.2-2.0). No significant differences were seen for treatment duration. The main limitations of existing evidence pertained to risk of bias, inconsistency, and imprecision of included studies. Conclusions: Orthodontic treatment with aligners is associated with worse treatment outcome compared to fixed appliances in adult patients. Current evidence does not support the clinical use of aligners as a treatment modality that is equally effective to the gold standard of braces

Cardiovascular Disease and Chronic Endodontic Infection. Is There an Association? A Systematic Review and Meta-Analysis

The aim of the present study was to systematically assess existing evidence on the possible association between chronic endodontic infections and cardiovascular disease (CVD). An electronic database search was implemented until 2 October 2020. The main outcome was risk of CVD diagnosis. Risk of bias was assessed through the ROBINS-I tool, while random effects meta-analyses were conducted. The quality of the evidence was assessed with the Grading of Recommendations Assessment, Development, and Evaluation. Twenty-one studies were eligible for inclusion, while 10 were included in the quantitative synthesis. Risk for CVD diagnosis in patients with chronic endodontic infection was 1.38 times those without infection (RR = 1.38; 95% CIs: 1.06, 1.80; p = 0.008). Risk of bias ranged from moderate to serious, while the quality of the evidence was graded as very low. Indications for an identified association between chronic endodontic infection and CVDs do exist; however, they are not grounded on high-quality evidence at present. Further research for an establishment of an association based on temporal sequence of the two entities and on unbiased well-conducted cohort studies would be highly valued

Εffect of cleansers on the composition and mechanical properties of orthodontic aligners in vitro

BACKGROUND The aim of the study was to investigate the effect of three aligner cleaners on the composition and mechanical properties of two types of orthodontic aligners. MATERIALS AND METHODS The cleaners tested were two alkaline peroxide solutions (Retainer Brite-RB; Retainer Cleaner-RC) and one peroxide-free (Steraligner-ST) and the aligners Clear Aligner (C, polyester) and Invisalign (I, polyester-urethane). The aligners were immersed in the cleaner solutions as instructed every day (15 min for RB, RC; 5 min for ST) for a two-week period. The acidity of the solutions was tested with a pH meter. The changes in the chemical composition of the aligners were studied by attenuated total-reflection Fourier transform infrared spectrometry (ATR-FTIR), while Instrumented Indentation Testing (IIT) was used for assessment of changes in Martens Hardness (HM), modulus (E$_{IT}$), elastic index (n$_{IT}$) and relaxation (R$_{IT}$). RESULTS RB and RC were weakly acidic (pH = 6.3), whereas ST was mildly acidic (pH = 4.8). The ATR-FTIR analysis demonstrated evidence of acidic hydrolysis of C in ST and I in RB. The IIT-derived properties of I were not affected by the cleaners. However, for C a significant change was found in HM (all cleaners), n$_{IT}$ (all cleaners) and R$_{IT}$ (RB, ST). Although the chemical changes support a hydrolytic material deterioration, the results of mechanical properties may interfere with the material residual stresses during fabrication. CONCLUSIONS Caution should be exerted in the selection of aligner cleaners. The mild acidic cleanser was more aggressive to the polyester, whereas an alkaline peroxide to the polyester-urethane aligner

Cytotoxicity and estrogenicity of a novel 3-dimensional printed orthodontic aligner

INTRODUCTION Orthodontic aligners printed with in-office 3-dimensional (3D) procedures have been described, but no data on their biocompatibility exist. This study investigates the cytotoxicity and estrogenicity of a 3D-printed orthodontic aligner by assessing its biological and behavioral effects. METHODS Ten sets of 1 type of aligner were immersed in sterile deionized water for 14 days, and the cytotoxicity and estrogenicity of released factors were assessed via MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assays on human gingival fibroblasts and the estrogen-sensitive MCF-7 and the estrogen-insensitive MDA-MB-231 breast cancer cell lines. 17β-Estradiol and bisphenol-A were used as positive controls. The statistical analysis of data was performed with generalized linear models at a 0.05 level of significance. RESULTS No signs of cytotoxicity were seen for the aligner samples for concentrations (v/v) of 20% (P = 0.32), 10% (P = 0.79), or 5% (P = 0.76). The antioxidant activity expressed as the capacity to reduce intracellular levels of reactive oxygen species was not affected in the aligner samples (P = 0.08). No significant estrogenicity was induced by the aligner samples compared with eluents from the negative control for both MCF-7 (P = 0.65) and MDA-MB-231 (P = 0.78). As expected, 17β-Estradiol and bisphenol-A stimulated MCF-7 cell proliferation, whereas no effect was observed on MDA-MB-231 cells. CONCLUSIONS In conclusion, if any factors were released during the 14-day aging of 3D-printed aligners in water, these were not found to be cytotoxic for human gingival fibroblasts and did not affect their intracellular reactive oxygen species levels. Moreover, no estrogenic effects of these putative eluates were observed based on an E-screen assay

Εffect of cleansers on the composition and mechanical properties of orthodontic aligners in vitro

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Particulate Production and Composite Dust during Routine Dental Procedures. A Systematic Review with Meta-Analyses

Composite dust generation is most likely a continuous and daily procedure in dental practice settings. The aim of this systematic review was to identify, compile and evaluate existing evidence on interventions and composite material properties related to the production of aerosolized dust during routine dental procedures. Seven electronic databases were searched, with no limits, supplemented by a manual search, on 27 April 2020 for published and unpublished research. Eligibility criteria comprised of studies of any design, describing composite dust production related to the implementation of any procedure in dental practice. Study selection, data extraction and risk of bias (RoB) assessment was undertaken independently either in duplicate, or confirmed by a second reviewer. Random effects meta-analyses of standardized mean differences (SMD) with associated 95% confidence intervals (CIs) were employed where applicable. A total of 375 articles were initially identified, resulting in 13 articles being included in the qualitative synthesis, of which 5 contributed to meta-analyses overall. Risk of bias recordings ranged between low and high, pertaining to unclear/raising some concerns, in most cases. All types of composites, irrespective of the filler particles, released significant amounts of nano-sized particles after being ground, with potentially disruptive respiratory effects. Evidence supported increased % distribution of particles < 100 nm for nanocomposite Filtek Supreme XTE compared to both conventional hybrid Z100MP (SMD: 1.96, 95% CI: 0.85, 3.07; p-value; 0.001) and nano- hybrid Tetric EvoCeram (SMD: 1.62, 95% CI: 0.56, 2.68; p-value: 0.003). For cytotoxicity considerations of generated aerosolized particles, both nanocomposites Filtek Supreme XTE and nanohybrid GradiO revealed negative effects on bronchial epithelial cell viability, as represented by % formazan reduction at 330–400 μg/mL for 24 hours, with no recorded differences between them (SMD: 0.19; 95% CI: −0.17, 0.55; p-value: 0.30). Effective and more rigorous management of dental procedures potentially liable to the generation of considerable amounts of aerosolized composite dust should be prioritized in contemporary dental practice. In essence, protective measures for the clinician and the practices’ personnel should also be systematically promoted and additional interventions may be considered in view of the existing evidence

In vitro simulation and In vivo assessment of tooth wear: a meta-analysis of In vitro and clinical research

Tooth wear may be described as a side-effect of occlusal forces that may be further induced by the common use of contemporary prosthetic materials in practice. The purpose of this systematic review was to appraise existing evidence on enamel wear from both in vitro and clinical research and explore whether evidence from these study designs lies on the same direction. Five databases of published and unpublished research were searched without limitations in August 2019 and study selection criteria included in vitro and clinical research on enamel tooth wear. Study selection, data extraction, and risk of bias assessment were done independently and in duplicate. Random effects meta-analyses of standardized mean differences (SMDs) or weighted mean differences (WMDs) with 95% confidence intervals (CIs) were conducted while a Monte Carlo permutation test for meta-regression on the exploration of the effect of the study design on the reported outcomes was planned. A total of 27 studies (23 in vitro and 4 clinical) were eligible while 12 contributed to meta-analyses. Overall, some concerns were raised for the quality of the existing evidence and the potential for risk of bias. Enamel wear (mm) of antagonist teeth was more pronounced when opposed to conventional porcelain compared to machinable ceramics (SMD = 2.18; 95%CIs: 1.34, 3.02; p < 0.001). Polished zirconia resulted in decreased volumetric enamel wear (mm3) of opposing teeth compared to pure natural enamel (SMD = –1.06; 95%CIs: –1.73, –0.39; p = 0.002). Monolithic zirconia showed evidence of enhanced potential for antagonist wear (μm) compared to natural teeth (WMD = 107.38; 95%CIs: 30.46, 184.30; p = 0.01). Study design did not reveal an effect on the tooth wear outcome for the latter comparison when both clinical and in vitro studies were considered (three studies; Monte Carlo test, p = 0.66). In conclusion, there is an overriding need for additional evidence from clinical research to substantiate the findings from the already existing laboratory simulation studies

Early responses of human periodontal ligament fibroblasts to cyclic and static mechanical stretching

OBJECTIVE To compare the mechanotransduction caused by cyclic and static mechanical strains in human periodontal ligament fibroblasts (hPDLFs) cultured under identical conditions. MATERIALS AND METHODS hPDLFs, originating from the same donors, were exposed either to cyclic or to static tensile strain using specially designed devices and under identical culture conditions. Activation of all members of mitogen-activated protein kinases (MAPKs) was monitored by western immunoblot analysis. Expression levels of immediate/early genes c-fos and c-jun were assessed with quantitative real-time polymerase chain reaction. RESULTS Time course experiments revealed that both types of stresses activate the three members of MAPK, that is ERK, p38, and JNK, with cyclic stress exhibiting a slightly more extended activation. Further downstream, both stresses upregulate the immediate/early genes c-fos and c-jun, encoding components of the activator protein-1 (AP-1), a key transcription factor in osteoblastic differentiation; again cyclic strain provokes a more intense upregulation. Six hours after the application of both strains, MAPK activation and gene expression return to basal levels. Finally, cells exposed to cyclic stress for longer periods are distributed approximately perpendicular to the axis of the applied strain, whereas cells exposed to static loading remain in a random orientation in culture. CONCLUSION The findings of the present study indicate similar, although not identical, immediate/early responses of hPDLs to cyclic and static stretching, with cyclic strain provoking a more intense adaptive response of these cells to mechanical deformation

Particulate production and composite dust during routine dental procedures. A systematic review with meta-analyses

Composite dust generation is most likely a continuous and daily procedure in dental practice settings. The aim of this systematic review was to identify, compile and evaluate existing evidence on interventions and composite material properties related to the production of aerosolized dust during routine dental procedures. Seven electronic databases were searched, with no limits, supplemented by a manual search, on 27 April 2020 for published and unpublished research. Eligibility criteria comprised of studies of any design, describing composite dust production related to the implementation of any procedure in dental practice. Study selection, data extraction and risk of bias (RoB) assessment was undertaken independently either in duplicate, or confirmed by a second reviewer. Random effects meta-analyses of standardized mean differences (SMD) with associated 95% confidence intervals (CIs) were employed where applicable. A total of 375 articles were initially identified, resulting in 13 articles being included in the qualitative synthesis, of which 5 contributed to meta-analyses overall. Risk of bias recordings ranged between low and high, pertaining to unclear/raising some concerns, in most cases. All types of composites, irrespective of the filler particles, released significant amounts of nano-sized particles after being ground, with potentially disruptive respiratory effects. Evidence supported increased % distribution of particles < 100 nm for nanocomposite Filtek Supreme XTE compared to both conventional hybrid Z100MP (SMD: 1.96, 95% CI: 0.85, 3.07; p-value; 0.001) and nano- hybrid Tetric EvoCeram (SMD: 1.62, 95% CI: 0.56, 2.68; p-value: 0.003). For cytotoxicity considerations of generated aerosolized particles, both nanocomposites Filtek Supreme XTE and nanohybrid GradiO revealed negative effects on bronchial epithelial cell viability, as represented by % formazan reduction at 330-400 μg/ml for 24 hours, with no recorded differences between them (SMD: 0.19; 95% CI: -0.17, 0.55; p-value: 0.30). Effective and more rigorous management of dental procedures potentially liable to the generation of considerable amounts of aerosolized composite dust should be prioritized in contemporary dental practice. In essence, protective measures for the clinician and the practices' personnel should also be systematically promoted and additional interventions may be considered in view of the existing evidence

Υλικά και κλινικές απόψεις για την ορθοδοντική θεραπεία με διαφανείς νάρθηκες

The use of orthodontic aligners to treat a variety of malocclusions has considerably increased in the last years. Yet evidence on forces and moments generated across difference aligners types, their efficacy and adverse effects relative to conventional fixed orthodontic appliances, accuracy obtained on specific tooth movements, the effect of aligner cleaners on their composition and mechanical properties and changes in the morphology, roughness and composition of attachment surfaces in contact with the aligners remain unclear. Aim: The aim of the present thesis was to study: (i) the existing evidence on forces exerted by aligners, (ii) the efficacy of aligners compared to orthodontic treatment with fixed appliances, (iii) the accuracy of specific tooth movements, (iv) the effects of aligner cleaners and (v) the aligner/attachment surfaces during orthodontic treatment with aligners. Methods: Two systematic reviews with meta-analyses were conducted to address the issues regarding the existing evidence on forces and moments generated by aligner type appliances and aligner efficacy and adverse effects relative to conventional treatment with fixed appliances. Seven and eight databases were searched without limitations for each topic respectively. Risk of bias assessment was based on the Cochrane Risk of Bias tool in all cases. A total of 13 in-vitro studies deemed eligible for inclusion and 2 were included in the quantitative synthesis for the former subject, whereas 11 studies (4 randomized/7 non-randomized) and 3 meta-analyses were conducted for the latter subject. Accuracy obtained from aligner treatment on specific tooth movements was measured by superimposing the predicted and achieved models over the initial ones in 20 Class I adult patients on posterior teeth. Moreover, the impact of three aligner cleaners was tested employing two alkaline peroxide solutions (Retainer Brite - RB; Retainer Cleaner - RC) and one peroxide-free (Steraligner - ST) on two different aligner companies, Clear Aligner (polyester) and Invisalign(polyester-urethane) for a two-week period. The acidity, changes in the chemical composition and changes in Martens Hardness (HM), elastic modulus (EIT), elastic index (nIT) and relaxation (RIT) were studied. Finally, attachments bonded with 2 different light-cured composite resins (sculptable and flowable) to 20 zirconia CAD/CAM frames and corresponding aligners, were examined before and after aligner removal and reseating in water, under (i) a stereomicroscope to identify morphological alterations, (ii) an optical profiler to measure the 3D-roughness parameters and (iii) by attenuated total reflection FTIR spectroscopy (ATR-FTIR) to determine changes in the molecular composition and degree of C=C conversion. Results: When palatal tipping of the upper central incisor through PET-G aligners was considered, aligner thickness of 0.5, 0.625 or 0.75 mm was not associated with a significantly different moment to force (M/F) ratio. Aligner thickness does not appear to possess a significant role in forces and moments generated by clear aligners under specific settings, while the most commonly examined tooth movements are tipping and rotation. Moderate quality evidence indicated that treatment with orthodontic aligners is associated with worse occlusal outcome with the American Board of Orthodontics Objective Grading System and more patients with unacceptable results. No significant differences were seen for treatment duration. Horizontal movements of all incisors seemed to be accurate, with small (0.20-0.25 mm) or insignificant differences between predicted and achieved amounts. Vertical movements and particularly intrusions of maxillary central incisors were found to be less accurate, with a median difference of 1.5 mm (p<0.001). All achieved rotations were significantly smaller than those predicted, with the maxillary canines exhibiting the greatest difference of 3.05o (p<0.001). RB and RC aligner cleaners were weakly acidic (pH = 6.3), whereas ST was mildly acidic (pH = 4.8). The ATR-FTIR analysis demonstrated evidence of acidic hydrolysis of Clear Aligner in ST and Invisalign in RB. The IIT-derived properties of Invisalign were not affected by the cleaners. However, for Clear Aligner a significant change was found in HM (all cleaners), nIT (all cleaners) and RIT (RB, ST). Finally, characteristic abrasion-induced defects by removal and reseating of the aligners were detected without significant changes in the roughness parameters (control-tested), but with significant higher values in Sdr between materials within control or tested groups. The sculptable material appeared superior in terms of morphology and retention characteristics. Insignificant differences in the C=C conversion were found in the groups tested. However, in some specimens strong peaks or irreversibly absorbed water were detected indicating hydrolytic susceptibility of the superficial composite zone.Υπόβαθρο: Η χρήση ορθοδοντικών ναρθήκων στην ορθοδοντική θεραπεία έχει αυξηθεί σημαντικά τα τελευταία χρόνια. Ωστόσο, ενδείξεις σχετικά με τις δυνάμεις και τις ροπές που ασκούνται, την αποτελεσματικότητα και τις ανεπιθύμητες ενέργειες των διαφανών ναρθήκων σε σύγκριση με τους συμβατικούς ακίνητους ορθοδοντικούς μηχανισμούς, την ακρίβεια που επιτυγχάνεται σε συγκεκριμένες οδοντικές μετακινήσεις, την επίδραση των ειδικών καθαριστικών ναρθήκων στη σύνθεση και τις μηχανικές τους ιδιότητές τους, καθώς και τις αλλαγές στη μορφολογία, την τραχύτητα και τη σύνθεση των επιφανειών των attachments που έρχονται σε επαφή με τους νάρθηκες, παραμένουν ασαφείς. Σκοπός: Ο σκοπός της παρούσας διατριβής ήταν να μελετηθούν: (i) οι υπάρχουσες ενδείξεις για τις δυνάμεις που ασκούνται από τους ορθοδοντικούς νάρθηκες, (ii) η αποτελεσματικότητα των ναρθήκων σε σύγκριση με την ορθοδοντική θεραπεία με ακίνητους μηχανισμούς, (iii) η ακρίβεια συγκεκριμένων οδοντικών κινήσεων, (iv) οι επιδράσεις των ειδικών καθαριστικών και (v) οι επιφάνειες νάρθηκων/attachments. Μέθοδοι: Δύο συστηματικές ανασκοπήσεις με μετα-αναλύσεις πραγματοποιήθηκαν σχετικά με τις υπάρχουσες ενδείξεις για τις δυνάμεις και τις ροπές που ασκούνται κατά τη χρήση ορθοδοντικών ναρθήκων καθώς και για την αποτελεσματικότητα των ορθοδοντικών ναρθήκων σε σύγκριση με συμβατικές θεραπείες με ακίνητους ορθοδοντικούς μηχανισμούς. Ερευνήθηκαν επτά και οκτώ βάσεις δεδομένων χωρίς περιορισμούς για κάθε θέμα, αντίστοιχα. Η εκτίμηση του κινδύνου μεροληψίας βασίστηκε στο εργαλείο Cochrane Risk of Bias. Συνολικά, 13 μελέτες in vitro επιλέχθηκαν και 2 συμπεριλήφθηκαν στη ποσοτική σύνθεση για το πρώτο θέμα, ενώ 11 μελέτες επιλέχθηκαν (4 τυχαιοποιημένες/7 μη τυχαιοποιημένες) και 3 μετα-αναλύσεις πραγματοποιήθηκαν για το δεύτερο θέμα. Η αποτελεσματικότητα της θεραπείας με ορθοδοντικούς νάρθηκες μετρήθηκε μέσω αλληλεπίθεσης των προβλεπόμενων και επιτευχθέντων μοντέλων σε σχέση με τα αρχικά σε 20 ενήλικες ασθενείς τάξης I σε οπίσθια δόντια. Επιπλέον, εξετάστηκε η επίδραση τριών καθαριστικών ναρθήκων χρησιμοποιώντας δύο με αλκαλικά υπεροξείδια (Retainer Brite - RB; Retainer Cleaner - RC) και ένα χωρίς υπεροξείδιο (Steraligner - ST) από δύο διαφορετικές εταιρείες ναρθήκων, Clear Aligner (πολυεστέρας) και Invisalign (πολυεστέρα-ουρεθάνης) για περίοδο δύο εβδομάδων. Μελετήθηκαν η οξύτητα, οι αλλαγές στη χημική σύνθεση και οι αλλαγές στη σκληρότητα (HM), το μέτρο ελαστικότητας (EIT), ο δείκτης ελαστικότητας (nIT) και η χαλάρωση (RIT). Τέλος, εξετάστηκε η επίδραση της αφαίρεσης και επανατοποθέτησης ναρθήκων στις επιφάνειες attachment σύνθετης ρητίνης (τοποθετημένα σε 20 σκελετούς ζιρκονίας CAD/CAM) σε νερό, (i) με στερεομικροσκόπιο για τον εντοπισμό μορφολογικών αλλαγών, (ii) με οπτικό προφιλόμετρο για τη μέτρηση των παραμέτρων τραχύτητας 3D και (iii) με φασματοσκοπία FTIR εξασθενημένης συνολικής ανάκλασης (ATR-FTIR) για να προσδιοριστούν αλλαγές στη μοριακή σύνθεση και το βαθμό μετατροπής του C=C. Αποτελέσματα: Κατά την απόκλιση του άνω κεντρικού τομέα με τη χρήση ναρθήκων PET-G πάχους 0.5, 0.625 ή 0.75 mm δεν παρατηρήθηκε σημαντική διαφορά στην αναλογία ροπής δύναμης (M/F). Το πάχος των διάφανων ναρθήκων δεν φαίνεται να παίζει σημαντικό ρόλο στις δυνάμεις και ροπές που ασκούνται υπό συγκεκριμένες συνθήκες, ενώ οι πιο συχνά εξεταζόμενες οδοντικές μετακινήσεις είναι η απόκλίση και η περιστροφή. Μέτριας ποιότητας δεδομένα έδειξαν ότι η θεραπεία με ορθοδοντικούς νάρθηκες σχετίζεται με χειρότερο τελικό αποτέλεσμα σύμφωνα με το Σύστημα Αντικειμενικής Βαθμολόγησης της Αμερικανικής Ορθοδοντικής Εταιρείας και περισσότερους ασθενείς με μη αποδεκτά αποτελέσματα. Ωστόσο, δεν παρατηρήθηκαν σημαντικές διαφορές στη διάρκεια της θεραπείας. Οι οριζόντιες κινήσεις όλων των τομέων ήταν ακριβείς, με μικρές (0.20-0.25 mm) ή ασήμαντες διαφορές μεταξύ των προβλεπόμενων και επιτευχθέντων αποτελεσμάτων. Οι κατακόρυφες κινήσεις, και ιδιαίτερα η εμβύθιση των άνω κεντρικών τομέων, βρέθηκαν να είναι λιγότερο προβλέψιμες, με μια μέση διαφορά 1.5 mm (p<0.001). Όλες οι περιστροφές ήταν σημαντικά μικρότερες από τις προβλεπόμενες, με τους άνω κυνόδοντες να παρουσιάζουν τη μεγαλύτερη διαφορά 3.05° (p<0.001). Τα καθαριστικά RB και RC ήταν ελαφρώς όξινα (pH = 6.3), ενώ το ST ήταν μέτρια όξινο (pH = 4.8). Η ανάλυση ATR-FTIR έδειξε στοιχεία όξινης υδρόλυσης του Clear Aligner και του Invisalign κατά την εμβάπτιση στο ST και στο RB αντίστοιχα. Στα αποτελέσματα για τη δοκιμασία IIT φαίνεται ότι το Invisalign δεν επηρεάστηκε από τα καθαριστικά. Ωστόσο, για το Clear Aligner παρατηρήθηκε σημαντική αλλαγή στο HM (όλα τα καθαριστικά), στο nIT (όλα τα καθαριστικά) και στο RIT (RB, ST). Τέλος, εντοπίστηκαν χαρακτηριστικά ελαττώματα λόγω τριβής από την αφαίρεση και επανατοποθέτηση των ναρθήκων στα attachments χωρίς σημαντικές αλλαγές στις παραμέτρους τραχύτητας (έλεγχο-δοκιμή), αλλά με σημαντικά υψηλότερες τιμές στο Sdr μεταξύ των υλικών εντός των ομάδων ελέγχου ή δοκιμής. Το πλαστικό υλικό φάνηκε ανώτερο σε όρους μορφολογίας και χαρακτηριστικών συγκράτησης. Μικρές διαφορές στην μετατροπή C=C παρατηρήθηκε στις δοκιμαζόμενες ομάδες. Ωστόσο, σε κάποια δείγματα ανιχνεύθηκαν ισχυρές κορυφές ή μη αναστρέψιμα απορροφημένο νερό, υποδεικνύοντας υδρολυτική ευαισθησία της επιφανειακής ζώνης