Color and Chemical Stability of 3D-Printed and Thermoformed Polyurethane-Based Aligners.

The significant rise in the use of clear aligners for orthodontic treatment is attributed to their aesthetic appeal, enhancing patient appearance and self-confidence. The aim of this study is to evaluate the aligners' response to common staining agents (coffee, black tea, Coca-Cola, and Red Bull) in color and chemical stability. Polyurethane-based thermoformed and 3D-printed aligners from four brands were exposed to common beverages to assess color change using a VITA Easyshade compact colorimeter after 24 h, 48 h, 72 h, and 7 days, as well as chemical stability using ATR-FTIR spectroscopy. The brand, beverage, and manufacturing method significantly influence color stability. ATR-FTIR analysis revealed compositional differences, with variations in response to beverage exposure affecting the integrity of polymer bonds. Color change analysis showed coffee as the most potent staining agent, particularly affecting Tera Harz TC85 aligners, while ClearCorrect aligners exhibited the least susceptibility. 3D-printed aligners showed a greater color change compared to thermoformed ones. Aligners with a PETG outer layer are more resistant to stains and chemical alterations than those made of polyurethane. Additionally, 3D-printed polyurethane aligners stain more than thermoformed ones. Therefore, PETG-layered aligners are a more reliable choice for maintaining the aesthetic integrity of aligners.

"Examining the link between tooth agenesis and papillary thyroid cancer: is there a risk factor?" Observational study.

BACKGROUND: Mutations in one or multiple genes can lead to hypodontia and its characteristic features. Numerous studies have shown a strong genetic influence on the occurrence of hypodontia, and identified several genes, including AXIN2, EDA, FGF3, FGFR2, FGFR10, WNT10A, MSX1, and PAX9, that are directly associated with dental agenesis and carcinogenesis. The objective of this study was to investigate the occurrence and pattern of tooth agenesis, microdontia, and palatally displaced canine (PDC) in women diagnosed with papillary thyroid cancer (PTC), compared to a control group of women without any malignancy or thyroid disease. MATERIALS AND METHODS: This case-control study was carried at the Department of Orthodontics, School of Dental Medicine University of Zagreb, and Department of Oncology and Nuclear Medicine Sestre Milosrdnice University Hospital Centre. The study involved a clinical examination and evaluation of dental status, panoramic X-ray analysis, and assessment of medical and family history of 116 female patients aged 20-40 with PTC, as well as 424 females in the control group who were of similar age. RESULTS: The prevalence of hypodontia, microdontia, and PDC was statistically higher in women with PTC than in the control group. The prevalence rate of hypodontia was 11.3% in the experimental group and 3.5% in the control group. The experimental group showed a higher occurrence of missing upper lateral incisors, lower left central incisors, and all the third molars (except the upper left) compared to the control group. Women with PTC showed the prevalence of PDC significantly higher than the control group (3.5%, 0.7%, p = 0.002). The probability of hypodontia as a clinical finding increases 2.6 times, and microdontia occurs 7.7 times more frequently in women with PTC. CONCLUSION: Our study suggests a possible link between odontogenesis and PTC. The absence of permanent teeth may increase the likelihood of PTC in women. Leveraging the age-7 orthopantomogram to identify women at high risk for PTC within a critical early detection window could significantly improve oral health outcomes and PTC prognosis through proactive interventions.

Influence of pH levels and beverage exposure on force decay and color stability of orthodontic elastomeric chains: An experimental study.

Aim of study: To assess the impact of pH level on force decay and color stability of orthodontic elastomeric chains (EOC) after exposure to commonly used beverages. Materials and methods: A total of 120 chain cuts were prepared from 2 different manufacturers (GC Orthodontics Europe GmbH, Breckerfeld, Germany, and FORESTADENT® - Bernhard Foerster GmbH, Pforzheim, Germany). According to the distance between loops, two types of chains were selected from each manufacturer: short and medium ones. Chains were immersed into 10 commonly used beverages with different pH values. After 7 days, force degradation was evaluated with the universal machine for mechanical testing (Model 4411; Instron, Canton, USA) and color change using a VITA Easyshade® digital spectrophotometer. Kruskal-Wallis with post-hoc Dunn's test for intergroup comparison and Wilcoxon rank test for intragroup comparison. Results: Initial force varied among EOC brands, with GC short chains having the highest force and Forestadent medium chains the lowest. The most pronounced force decay occurred within 24 h, notably affecting Forestadent short chains the most, followed by Forestadent medium, GC short, and GC medium chains. Despite a higher force drop rate over seven days, short EOCs maintained higher forces than medium EOCs. GC EOCs consistently maintained higher forces after seven days compared to Forestadent EOCs. After the immersion of EOC in different solutions for 24 h, only Evian water, Soy milk, and Coconut water did not change color. After 7 days, the greatest color change was recorded in coffee. Conclusion: There is no correlation between pH value and force decay of polyurethane chains. Short chains showed more constant force delivery and greater value of remaining force in comparison to medium ones. Color stability was mostly affected by coffee, followed by matcha tea, soy milk, and apple juice.

Influence of the Bracket Material on the Post-Cure Degree of Conversion of Resin-Based Orthodontic Adhesive Systems.

The aim of this study was to examine the influence of the orthodontic bracket material on the short-term and long-term post-cure development of the degree of conversion (DC) of resin-based orthodontic adhesive systems. Five commercially available materials characterized by different compositions and curing modes (light-curable or dual-curable) were tested under three different light curing conditions: without brackets (control group, CO), and in the presence of metal brackets (MB group) or ceramic brackets (CB group). Fourier-transform infrared spectroscopy was used to determine the post-cure DC development, both after "short-term" periods (2, 6, and 10 min) and "long-term" periods (1, 7, and 28 days). The short-term DC values ranged from 43.9% to 76.1%, and the long-term DC values were higher and ranged from 54.3% to 85.3%. The MB group demonstrated significantly lower short-term DC values compared to the CO and the CB groups, while the CB group had statistically similar or slightly lower DC values compared to the CO group. Long-term DC values in the MB and the CB groups were statistically lower or similar compared to the CO group, which depended on the post-cure time. The results indicated that the post-cure DC development was highly material-dependent and affected by the presence of different types of bracket material.

Awareness and usage of mobile applications as an orthodontic diagnostic tool among Croatian orthodontic clinicians.

OBJECTIVE: To assess the impact of gender and orthodontic qualification length on the awareness, knowledge and usage of orthodontic diagnostic mobile applications, non-diagnostic mobile applications and social media platforms among orthodontic clinicians. DESIGN: Cross-sectional questionnaire-based study. SETTING: The Republic of Croatia. PARTICIPANTS: A total of 92 orthodontic specialists, members of the Croatian Dental Chamber. METHODS: This study was conducted using a questionnaire distributed via email to orthodontic clinicians between May and July 2022. RESULTS: In total, 92 respondents were divided into groups according to sex and median orthodontic qualification length: more recently qualified (MRQ) with ⩽12 years; and longer qualified (LQ) with >12 years. Nearly one-third of respondents did not have any prior knowledge of mobile applications used as an orthodontic diagnostic tool. MRQ respondents were more interested in using mobile apps as opposed to computer software for digital analysis (P < 0.05). This interest was in a negative correlation with orthodontic qualification length (P < 0.01) and was more prevalent among female respondents (P < 0.001). About one-third (32.6%) of respondents did not use non-diagnostic mobile applications and 44.6% did not use social media platforms. Nearly two-thirds (62%) of the respondents did not promote their work through social media. Male respondents and LQ promoted their work more frequently than others (P < 0.05). The usage of other mobile applications was in a positive correlation with the knowledge and awareness of orthodontic mobile applications (P < 0.05). CONCLUSION: Orthodontic clinicians lacked knowledge, awareness and the usage of orthodontic diagnostic mobile applications according to sex and orthodontic qualification length. One-third used non-diagnostic mobile applications and less than half used social platforms in daily clinical work.

Resistance of PETG Materials on Thermocycling and Brushing.

The aim was to assess the impact of thermocycling and brushing on the surface roughness and mass of PETG material-the most commonly used for orthodontic retainers. A total of 96 specimens were exposed to thermocycling and brushing with three different kinds of toothbrushes depending on the number and thickness of the bristles. Surface roughness and mass were evaluated three times: initially, after thermocycling, and after brushing. In all four brands, both thermocycling and brushing increased surface roughness significantly (p < 0.001), with Biolon having the lowest and Track A having the highest. In terms of brushing, only Biolon samples showed statistically significant increased roughness after brushing with all three types of brushes, in comparison to Erkodur A1, where differences were not statistically significant. Thermocycling increased the mass of all samples, but a statistically significant difference was found only in Biolon (p = 0.0203), while after brushing, decreased mass was found in all specimens, statistically significant only in Essix C+ (CS 1560: p = 0.016). PETG material showed instability when exposed to external influences- thermocycling produced an increase in roughness and mass, and brushing mostly caused an increase in roughness and decrease in mass. Erkodur A1 demonstrated the greatest stability, whereas Biolon demonstrated the lowest.

Correlation of Shear Bond Strength and Degree of Conversion in Conventional and Self-Adhesive Systems Used in Orthodontic Bonding Procedures.

(1) Background: Self-adhesive systems have been proposed for the orthodontic bonding with the intention to reduce the traditional three-component system. (2) Methods: The sample consisted of 32 extracted intact permanent premolars randomly divided into two groups (n = 16). In Group I the metal brackets were bonded with Transbond XT Primer and Transbond XT Paste. In Group II the metal brackets were bonded with GC Ortho connect. The resin was polymerized for 20 s from two directions (mesial and occlusal) using a Bluephase light-curing unit. The shear bond strength (SBS) was measured using a universal testing machine. Immediately after SBS testing, Raman microspectrometry was performed for each sample to calculate the degree of conversion (DC). (3) Results: There was no statistically significant difference in the SBS between the two groups. A significantly higher DC (p < 0.001) value was recorded in Group II, in which the brackets were bonded with GC. Very weak or no correlation (0.01) was recorded between SBS and DC in Group I and moderate positive correlation was recorded in Group II (0.33). (4) Conclusions: No difference was found in SBS between the conventional and two-step systems used in orthodontics. The two-step system demonstrated higher DC compared to the conventional system. There is a very weak or moderate correlation between DC and SBS.

Influence of Post-Processing on the Degree of Conversion and Mechanical Properties of 3D-Printed Polyurethane Aligners.

BACKGROUND: This study explores how different post-processing methods affect the mechanical properties and degree of conversion of 3d-printed polyurethane aligners made from Tera Harz TC-85 resin. METHODS: Using Fourier-transform infrared (FTIR) spectroscopy, the degree of conversion of liquid resin and post-processed materials was analyzed. This investigation focused on the effects of various post-curing environments (nitrogen vs. air) and rinsing protocols (centrifuge, ethanol, isopropanol, and isopropanol + water). The assessed mechanical properties were flexural modulus and hardness. RESULTS: The degree of conversion showed no significant variance across different groups, though the polymerization environment influenced the results, accounting for 24.0% of the variance. The flexural modulus varied considerably, depending on both the rinsing protocol and the polymerization environment. The standard protocol (centrifugation followed by nitrogen polymerization) exhibited the highest flexural modulus of 1881.22 MPa. Hardness testing revealed significant differences, with isopropanol treatments showing increased resistance to wear in comparison to the centrifuge and ethanol rinse treatments. CONCLUSIONS: This study conclusively demonstrates the adverse effects of oxygen on the polymerization process, underscoring the critical need for an oxygen-free environment to optimize material properties. Notably, the ethanol rinse followed by nitrogen polymerization protocol emerged as a viable alternative to the conventional centrifuge plus nitrogen method.

Differential Stability of One-layer and Three-layer Orthodontic Aligner Blends under Thermocycling: Implications for Clinical Durability.

Objectives: To optimize the therapeutic usefulness of aligners, it is crucial to understand how their mechanical properties alter with time. Materials and methods: Specimens from four different brands, including Duran+, CA® Pro, Zendura A, and Zendura FLX, were produced for material testing of thermoplastic orthodontic aligners (TOA) using dimensions measuring 4mm x 10mm. Each brand's 24 samples were split into three groups as follows: G1 being thermoformed, G2 being thermoformed and underwent 500 thermocycles (simulating 7 days), and G3 being thermoformed and underwent 1000 thermocycles (simulating 14 days). Surface roughness, modulus of elasticity in bending, and spectrophotometry were used to assess the effect of aging on TOAs. Results: After 1000 thermocycles, Duran+ had the highest modulus of elasticity and differed statistically from all other groups. The intragroup comparison showed that only Duran+'s elastic modulus significantly changed after 1000 thermocycles in comparison with the control group. Surface roughness values (Ra), did not statistically differ among brands or thermocycling group measures. The change in chemical properties was not significant in any brand. Conclusion: One-layer PETG (Duran+) failed to demonstrate stability after in vitro aging, thus suggesting that clinicians should be aware of the change in mechanical properties when using one-layer PETG (Duran +) in a 2 weeks regime.

Color Stability of Orthodontic Ceramic Brackets and Adhesives in Potentially Staining Beverages-In Vitro Study.

The aim of this study was to evaluate the color stability of esthetic ceramic brackets and adhesive samples after immersion in most commonly consumed beverages. A hundred ceramic brackets from five different manufacturers (Forestadent®, G&H®, GC, DynaFlex®, and American Orthodontics) and 120 samples of adhesives (3M™Transbond™ XT and American Orthodontics BracePaste® color change adhesive and BracePaste® adhesive) were immersed into four different solutions: coffee, Coca-Cola®, the vitamin drink Cedevita®, and artificial saliva (control group). The samples were kept in an incubator at 37 °C. Color readings were evaluated before (T0), at 24 h (T1), 72 h (T3), 7 days (T4), and 14 days (T5) after initial immersion using a spectrophotometer according to the L*a*b* color scale. All the examined brackets showed a statistically significant difference in discoloration (p = 0.001). 20/40™ Brackets (American Orthodontics) showed the best color stability, while the greatest color modification was recognized in QuicKlear® III (Forestadent®) brackets. Regarding adhesives, the greatest staining was observed in the BracePaste® color change adhesive and the least in the Transbond™ XT samples. In conclusion, color change occurs in all solutions, including control groups, and coffee has the greatest impact on color stability.

Dental and Skeletal Age in Patients with Palatally Displaced Canines.

Objective: To determine potential associations between dental and skeletal maturation and palatally displaced canines (PDC) considering gender and chronological age. Material and methods: This study included pretreatment panoramic and lateral cephalometric radiographs of 43 subjects with PDCs and 203 randomly selected orthodontic subjects with normally erupted canines. Both groups were non syndromic patients. Chronological age of subjects was rounded and noted in years with decimal points and compared with chronological age according to Demirjian's dental age assessment. Skeletal maturation was determined by cervical vertebrae changes on cephalometric radiographs. Results: Female subjects with PDC were more affected by left side canine displacement than males (p=0.027) with five times higher odds ratio (OR = 4.9; 95% CIL=1.2-19.7). A comparison of chronologic and skeletal age indicated that PDC subjects were skeletally younger than unaffected groups with statistically significant differences at the age of 10, 12 and 13. (p=0.05). Conclusion: Young subjects with PDCs showed skeletal maturation delay compared to control group, indicating that skeletal maturation assessment could be one of unexplored predicting factors of a PDC, especially at the age between 10 and 13 years in both genders. Subjects with PDC showed intensive growth spurt after the age of 12 years in females, and after the age of 13 in males. Dental maturation delay showed no statistical significance in PDC prediction.

Prevalence of Dental Anomalies in Orthodontic Patients.

Aim: The aim of this retrospective study was to determine the frequency of hypodontia, hyperdontia, invagination, impaction, dilacerations, peg-shaped lateral incisors, taurodontism and short or blunt and narrow or pipette-shaped roots in Croatian orthodontic patients. Material and methods: 506 orthopantomographs and study casts from 12-16 year-old orthodontic patients treated at the Department of Orthodontics, School of Dental Medicine University of Zagreb were analyzed. Results: At least one dental anomaly was present in 24.1% of patients, and more than anomaly in 1.2% of them. The frequency was not significantly different between genders. Hypodontia was the most frequent anomaly with the incidence of 7.5%, followed by teeth impaction with the incidence of 6.3%. Conclusion: The distribution and the prevalence of anomalies were similar to those described in the general Croatian population.

Knowledge and Attitude towards Orthodontic Treatment among Non-Orthodontic Specialists: An Online Survey in Croatia.

OBJECTIVES: The aim of this study was to examine the knowledge and attitudes towards orthodontic treatment among non-orthodontic specialists. METHODS: A web-based survey was formulated for non-orthodontic dental specialists to respond to statements regarding an orthodontic treatment. It contained 20 multiple-choice questions with three or more possible answers. Two hundred and fifty questionnaires were sent via email, with explanatory letters, to randomly selected non-orthodontic Croatian dental specialists. Data were assessed using IBAM SPSS 23.0. and p < 0.01 was considered significant. RESULTS: The results indicate that the majority of respondents were well informed about principles and practices in orthodontics. All the respondents (100%) were aware that malocclusions can affect a patient's facial aesthetic and masticatory function. The results also showed statistically significant differences in answers about contraindications for orthodontics therapy among different non-orthodontic specialists (p < 0.01). Private health practitioners were better informed about the ideal time for the first orthodontic appointment (74.2%) and that implants and periodontal problems are not contraindications for orthodontic treatment (over 70%), in comparison with public health practitioners. CONCLUSION: Non-orthodontic specialists in this sample exhibit encouraging awareness and knowledge of the principals and practices of orthodontic treatment. Additional improving of practitioners' knowledge and awareness can help patients with malocclusion to decide upon orthodontic treatment at earlier stages and avoid later complications in the future.

Sudden, Severe, Idiopathic Occlusal Relationship Change Coexisting with Pain-Related Temporomandibular Disorders: A Case Report.

The article presents a case of a young female patient who sought help due to myofascial pain followed by a sudden occlusal change (anterior open bite (AOB)) that occurred shortly after the administration of a soft night guard that had been previously provided by a general dentist. Palpation of the masseter and temporal muscles elicited the presence of familiar pain. After magnetic resonance imaging of temporomandibular joints, which ruled out disc displacement, the final diagnosis was myalgia. Since the patient had myalgia and malocclusion, the therapy included treatment of both conditions. Temporomandibular disorders (TMDs) management included a combination of kinesiotherapy, pharmacotherapy, and a stabilization splint. After TMD symptoms had resolved, the patient underwent an orthodontic evaluation. Cephalometric analysis revealed skeletal class II, retrognathic face, convex profile, and normal vertical growth pattern. Orthodontic treatment included a fixed appliance with vertical intermaxillary elastics. After 19 months of treatment, both sides achieved acceptable occlusion with Class I. Since the patient had myalgia and severe malocclusion, it was important to follow a systematic diagnostic and therapeutic workflow. Although it is impossible to establish a relationship between TMD symptoms and orthodontic therapy, patients who have TMD symptoms should have their pain resolved through a conservative treatment protocol before commencement of orthodontic treatment. The beginning of orthodontic therapy comes into consideration only when the TMD pain resolves.

Skeletal Maturation in Different Vertical Facial Growth Pattern.

OBJECTIVE: To assess whether there are differences in skeletal maturation among subjects with horizontal, vertical, and neutral facial growth patterns. MATERIAL AND METHODS: The study was performed on 48 latero-lateral craniographs of patients with horizontal, 48 with vertical and 50 with neutral growth patterns aged 12 to 18 years. Eight variables from the Zagreb 82 MOD, Bracchetti and Accord analysis, were selected for measuring angular and linear parameters on latero-lateral craniographs. The assessment of skeletal maturation was done by using the CVMS method. RESULTS: Statistical analysis showed significant differences in skeletal maturity (p <0.001) between subjects with horizontal and vertical growth pattern and between the subjects with neutral and vertical growth pattern (p <0.05), while no significant difference was found between patients with horizontal and neutral growth pattern. In the younger group (12 - 15 years) there was a statistically significant difference (p <0.05) among subjects with horizontal and vertical growth patterns. In the older group (16 - 18 yrs) there was a statistically significant difference (p > 0.05) in skeletal maturity among subjects with vertical growth patterns compared with horizontal and neutral. In terms of stages of skeletal maturity, patients with a horizontal and neutral growth pattern in the younger group were on average in the fourth stage, and those with a vertical growth pattern in the third stage. In the older group, patients with a horizontal and neutral growth pattern were on average in the fifth stage of skeletal maturity and those with a vertical growth pattern in the fourth stage. CONCLUSION: According to the growth pattern, patients differ in the stage of skeletal maturity.

Prevalence and Pattern of Hypodontia among Croatian Orthodontic Patients.

OBJECTIVE: The objective of this retrospective study was to assess the prevalence of hypodontia in the permanent dentition among Croatian orthodontic patients. The occurrence was evaluated concerning gender, specific missing teeth, the location, pattern of distribution in the maxillary and mandibular arches and sagittal and vertical skeletal pattern. MATERIAL AND METHODS: The sample consisted of 194 patients (75 males and 119 females) from the Department of Orthodontics, Dental Clinic, Clinical Hospital Center Zagreb. Based on the severity of hypodontia the sample was divided into mild (1-2 missing teeth), moderate (3-5 missing teeth) and severe groups (6 or more missing teeth). The location of missing teeth was used to further divide the sample into anterior (intercanine region), posterior (premolars and molars) and anteroposterior groups. In addition, jaw localization of hypodontia was also considered. RESULTS: Permanent dentition hypodontia among Croatian orthodontic patients was found to be generally mild (80%), and a distribution was similar in the maxilla (39%) and the mandible (41%), as well as in the anterior and posterior segments of dental arch (44%). The number of missing teeth per person ranged from 1 to 12, with no significant difference between genders. The severity and location of hypodontia did not differ significantly between the genders, as well as in between the categories of sagittal and vertical skeletal patterns. CONCLUSION: Present results suggest that the treatment plan for patients with hypodontia in permanent dentition should be individualized and adjusted for each case.

Hide and seek: Impacted maxillary and mandibular canines from the Roman period Croatia.

OBJECTIVE: The aim of this paper was to analyse the dental remains of an adult male with three impacted canines from the Roman period cemetery in Osijek, Croatia. MATERIALS: The dental remains of an adult male aged 35-45 years at the time of death were analysed. METHODS: Macroscopic analysis of dental remains was accompanied by radiographic examination. RESULTS: The individual also had additional dental pathologies (carious lesion, antemortem tooth loss). A total of 21 permanent teeth were present in maxillae and mandible. Eighteen of them were normal fully erupted dentition, while three were impacted: left maxillary canine and both mandibular canines. The left maxillary and mandibular canines were mesially inclined, and the right mandibular canine was relatively horizontally positioned. CONCLUSION: A case of non-syndrome impaction in which the lack of eruptive force in combination with the unfavorable position of the tooth bud might have resulted in multiple impacted teeth is presented. SIGNIFICANCE: Current clinical knowledge reports low frequency of this anomaly, with maxillary impaction occurring more often than mandibular. Furthermore, canine impaction is even more rarely reported in the archaeological material. The presented case is the only one from the archaeological setting with impaction present both in maxillae and mandible. LIMITATIONS: In modern populations multiple impactions are often associated with various syndromes. Since the majority of syndromes affect soft tissue, their association with impaction cannot be confirmed in archaeological populations.

Linear Predictors of Facial Rotation Pattern in Croatian Subjects with Skeletal Class III Malocclusion.

OBJECTIVES: The objective of this study was to determine whether the linear measures of the maxilla, mandible and cranial base were predictors of facial growth rotation in a Croatian population with Class III malocclusion by cephalometric radiographic methods. MATERIAL AND METHODS: The examined sample consisted of pretreatment lateral cephalometric records of 201 (111 females and 90 males) untreated Class III patients of Caucasian Croatian ancestry from the Department of Orthodontics at Zagreb University. The measurements were divided into five categories for analysis: cranial base, skeletal maxillary and skeletal mandibular relationships, sagittal intermaxillary and vertical relationships. Five multiple linear regression models were used to identify predictors of facial rotation pattern. RESULTS: The effective length of the mandible was the most important predictor of facial rotation pattern, with the increased length largerly predisposing the tendency to the vertical growth pattern. No significant dichotomy was found regarding gender apart from the fourth model in which the posterior rotation of maxilla is related to female gender. CONCLUSION: These predictors could help orthodontists determine timing and therapy for Croatian patients with Class III malocclusions.

Shear Bond Strength of Orthodontic Brackets Luted with RMGIC After Er:YAG Laser Etching with Two Pulse Modes Using a Digitally Controlled "X-Runner" Handpiece.

OBJECTIVE: To compare the shear bond strength (SBS) values of orthodontic brackets luted using a resin-modified glass ionomer cement (RMGIC) on enamel surfaces etched using either an Er:YAG laser in two different working modes, or a conventional etching protocol, including phosphoric acid. MATERIALS AND METHODS: Sixty healthy human premolars were randomly allocated to three experimental groups (n = 20) and etched with: Group 1: Er:YAG laser in super-short pulse (SSP) mode (100 mJ, 20 Hz, 2 W); Group 2: Er:YAG laser in quantum square pulse mode (120 mJ, 10 Hz, 1.2 W) using a digitally controlled handpiece ("X-Runner"); Group 3 (control): 5.25% sodium hypochlorite pretreatment, then 37% phosphoric acid for 15 sec. Stainless steel brackets were bonded using light-curing RMGIC for orthodontic bonding. After term cycling (1800 cycles), SBS testing was performed using a universal testing machine. After debonding, both enamel and bracket surfaces were examined to determine the amount of RMGIC still present on the surfaces. RESULTS: Group 3 surfaces gave the lowest mean SBS (10.6104 ± 2.66196 MPa), whereas Group 1 provided the highest 1 (13.1795 ± 3.37904 MPa), which was significantly different from the control (Group 3, p = 0.0226). Group 2 provided intermediate values (11.8486 ± 0.59832 MPa) nonsignificantly different from the control or from SSP (p = 0.4215 and p = 0.3082, respectively). CONCLUSIONS: Er:YAG laser treatment in SSP mode of enamel surfaces for orthodontic bonding provided higher SBS and a shear behavior of the luting material similar to the conventional acid-etching procedures, making it a viable alternative to acid etching.

Mesiodistal and Buccolingual Dimensions in Croatian Orthodontic Hypodontia Patients' Teeth.

OBJECTIVE: This study compared mesiodistal (MD) and buccolingual (BL) tooth dimensions of hypodontia patients with a control group with complete dentition. The null hypothesis was that there was no difference in tooth sizes between hypodontia patients and the controls. METHODS: The sample comprised 76 patients with hypodontia (50 female and 26 male) aged between 11 and 18 years. The control group comprised 50 females and 26 males with the same age range as the study group. Mesiodistal (MD) and buccolingual (BL) dimensions were measured on pretreatment dental casts with a digital caliper to the nearest 0.01 mm. The data were analyzed using Statistica 7.1 (StatSoft Inc.) statistical package (descriptive statistics, test of distribution normality, parametric statistics). RESULTS: The most common congenitally missing teeth were the lower second premolars (left 13.45% and right 13.90%) and upper lateral incisors (both left and right 12.56%), followed by upper second premolars (right 9.4o% and left 10.31%). The greatest differences between the study and control group were found in upper lateral incisors, 8.08% in MD and 6.40% in BL dimension. The smallest difference was found in BL dimension of lower lateral incisor (2.37%), MD dimension of lower second premolars and upper first molar (2.61%) and MD dimension of lower central incisor (2.26%). CONCLUSION: The teeth are smaller in subjects with hypodontia than those of the controls on average 4.02% in MD dimension and 3.85% in BL dimension. The tooth that showed the greatest difference in tooth dimension was maxillary lateral incisor.