Paola Gandini

A Comparison of Hand-wrist Bone and Cervical Vertebral Analyses in Measuring Skeletal Maturation

OBJECTIVE To compare skeletal maturation as measured by hand-wrist bone analysis and by cervical vertebral analysis. MATERIALS AND METHODS A radiographic hand-wrist bone analysis and cephalometric cervical vertebral analysis of 30 patients (14 males and 16 females; 7-18 years of age) were examined. The hand-wrist bone analysis was evaluated by the Bjork index, whereas the cervical vertebral analysis was assessed by the cervical vertebral maturation stage (CVMS) method. To define vertebral stages, the analysis consisted of both cephalometric (13 points) and morphologic evaluation of three cervical vertebrae (concavity of second, third, and fourth vertebrae and shape of third and fourth vertebrae). These measurements were then compared with the hand-wrist bone analysis, and the results were statistically analyzed by the Cohen kappa concordance index. The same procedure was repeated after 6 months and showed identical results. RESULTS The Cohen kappa index obtained (mean +/- SD) was 0.783 +/- 0.098, which is in the significant range. The results show a concordance of 83.3%, considering that the estimated percentage for each case is 23.3%. The results also show a correlation of CVMS I with Bjork stages 1-3 (interval A), CVMS II with Bjork stage 4 (interval B), CVMS III with Bjork stage 5 (interval C), CVMS IV with Bjork stages 6 and 7 (interval D), and CVMS V with Bjork stages 8 and 9 (interval E). CONCLUSIONS Vertebral analysis on a lateral cephalogram is as valid as the hand-wrist bone analysis with the advantage of reducing the radiation exposure of growing subjects.

Correlations between rapid maxillary expansion (RME) and the auditory apparatus.

OBJECTIVE To evaluate the effects of rapid maxillary expansion (RME) on conductive hearing loss and maxillary constriction. MATERIALS AND METHODS A total of 25 subjects (15 girls and 10 boys, aged between 6 years 8 months to 8 years 2 months) with conductive hearing loss and maxillary constriction were studied. Audiogram, tympanogram, and video-otoscopy were used to investigate the anatomical and physiological modifications of the bony and muscular structure of the maxilla and the auditory apparatus. The records were taken before maxillary expansion (T0), after expansion (7-14 days; T1), and after the retention period (8 months after expansion; T2). RESULTS After expansion, the audiometric records indicated an improvement in hearing levels for higher frequencies but not for lower ones. After the retention period, there was a functional improvement in all patients for all frequencies. The recovery of the tympanic membranes elasticity occurred only after retention, as shown by the standard model tympanogram, which was still flat after expansion. CONCLUSIONS The auditory function in patients with conductive hearing loss may be corrected through correction of the palatal anatomy, which influences the muscular function of the tubal ostia and allows a normal activity of the tympanic membrane and the auditory apparatus. Positive effects on conductive hearing loss are possible additional benefits of RME treatment, but this does not indicate that patients with conductive hearing loss without an accompanying maxillary constriction should consider this as a treatment approach.

Efficacy of Esthetic Retainers: Clinical Comparison between Multistranded Wires and Direct-Bond Glass Fiber-Reinforced Composite Splints

The purpose of this longitudinal prospective randomized study was to evaluate the reliability of two different types of orthodontic retainers in clinical use: a multistrand stainless steel wire and a polyethylene ribbon-reinforced resin composite. Moreover the level of satisfaction of the patient about the esthetic result was also analyzed by means of a Visual Analogue Scale (VAS). 34 patients (9 boys and 25 girls, mean age 14.3), in the finishing phase of orthodontic treatment, were selected for the study. Since splints were applied the number, cause, and date of splint failures were recorded for each single tooth over 12 months. Statistical analysis was performed using a paired t-test, Kaplan Meier survival estimates, and the log-rank test. Kruskal Wallis test was performed to analyze VAS recordings. Differences between the bond failure rates were not statistically significant. Esthetic result of VAS was significantly higher for polyethylene ribbon-reinforced resin retainers than for stainless steel wires.

Clinical evaluation of bond failures and survival between mandibular canine- to-canine retainers made of flexible spiral wire and fiber-reinforced composite

Objectives: The purpose of this longitudinal prospective randomized study was to evaluate the clinical reliability of two different types of postorthodontic treatment retainers: a silanised-treated glass fibers-reinforced resin composite (FRC) and a directly bonded multistranded stainless steel wire. The hypothesis of the study was to assess if significant differences are present between failure rates of the two retainers. Study Design: This prospective study was based on an assessment of 87 patients (35 men and 52 women),with an average age of 24 years who required a lower arch fixed retainer after orthodontic treatment. Patients were divided in two groups. Assignment was carried out with random tables. A follow-up examination was carried out once a month. The number, cause, and date of single bond adhesive failures were recorded for both retainers over 12 months. Teeth that were rebonded after failure were not included in the success analysis. Statistical analysis was performed by means of a Fisher’s exact test, Kaplan-Meier survival estimates, and log rank test. Results: Bond failure rate was significantly higher (P=0.0392) for multistranded metallic wire than for FRC. Conclusions: Glass fiber-reinforced resin composite retainers and multistranded metallic wires showed no significant difference in single bond failure rates over a one-year follow up. Key words:Fiber reinforced composite, fixed retention, multistranded wire, orthodontics, retainer, splint.

Reconditioning of self-ligating brackets

OBJECTIVE To test the null hypothesis that there is no significant difference in the shear bond strength (SBS) and Adhesive Remnant Index (ARI) scores of new vs reconditioned self-ligating brackets. MATERIALS AND METHODS One hundred and twenty permanent extracted bovine teeth were embedded in resin blocks. Three different new and reconditioned self-ligating orthodontic brackets (Smart Clip [3M Unitek]; Quick [Forestadent]; and Damon3MX [Ormco]) were tested. Scanning electron microphotographs of the different new (groups 1, 3, and 5) and reconditioned (groups 2, 4, and 6) bracket bases were taken before starting the experiments. Brackets were then bonded to the teeth using an orthodontic adhesive and were then tested in shear mode using an Instron Universal Testing Machine. ARI scores were then recorded. Statistical analysis was performed to determine significant differences in SBS and ARI Scores. RESULTS Smart Clip and Damon3MX reconditioned brackets showed significantly lower SBS than did new ones. On the contrary, Quick reconditioned brackets showed significantly higher SBS than did new ones. No significant differences in ARI scores were found after the reconditioning process for the three different brackets tested. CONCLUSION The in-office reconditioning procedure alters the SBS of self-ligating brackets, although SBS values still remain clinically acceptable.

Effects of nanofillers on mechanical properties of fiber-reinforced composites polymerized with light-curing and additional postcuring

Background The purpose of the present study was to evaluate the effect of nanofillers on the mechanical properties of 2 sizes (diameters 0.6 and 0.9 mm) of conventional and nanofilled fiber-reinforced composites (FRCs) polymerized with conventional light-curing and additional postcuring. Methods The FRCs samples were divided into 8 groups (10 specimens each). Conventional FRCs with glass fibers preimpregnated with polymethyl methacrylate (groups 1, 2, 3 and 4) and FRCs with impregnating solution containing 32% nanofilled resin (groups 5, 6, 7 and 8) were tested in 2 different sections (0.6 and 0.9 mm in diameter). Two different polymerizations were analyzed: hand light-curing for 40 seconds with an halogen light, and additional postcuring for 25 minutes in a light-curing oven. Each sample was evaluated with a 3-point bending test on a universal testing machine, after 48 hours of dry storage. All of the data were statistically analyzed. Results After oven postcuring, nanofilled FRCs exhibited significantly higher load values than conventional FRCs. No significant differences were found when comparing conventional and nanofilled FRCs after hand light-curing. Moreover, 0.6-mm FRCs showed significantly lower load values than 0.9-mm FRCs, both for conventional and nanofilled FRCs. Conclusions Nanofilled FRCs showed higher load values after additional oven postcuring.

Disinclusion of unerupted teeth by mean of self-ligating brackets: effect of blood contamination on shear bond strength.

Objectives: The aim of this study was to assess the effect of blood contamination on the shear bond strength and failure site of three different orthodontic self-ligating brackets. Study Design: 240 bovine permanent mandibular incisors were randomly divided into 12 groups of 20 specimens each. Orthodontic self-ligating brackets were tested under four different enamel surface conditions: a) dry, b) blood contamination before priming, c) blood contamination after priming, d) blood contamination before and after priming. Brackets were bonded to the teeth and subsequently tested using a Instron universal testing machine. Shear bond strength values and adhesive failure rate were recorded. Statistical analysis was performed using ANOVA and Tukey tests (strength values), and Chi squared test (ARI Scores). Results: Non-contaminated enamel surfaces showed highest bond strengths for all self ligating brackets. Under blood-contamination shear bond strengths lowered for all brackets tested. Groups contaminated before and after primer application showed the lowest shear bond strength. Significant differences in debond locations were found among the groups under the various enamel surface conditions. Conclusions: Blood contamination of enamel during the bonding procedure lowers bond strength values of self ligating brackets, expecially when contamination occur in different times of the bonding procedure. Key words:Disinclusion, self ligating brackets, blood, contamination, enamel, orthodontics, oral surgery.

The Influence of No-Primer Adhesives and Anchor Pylons Bracket Bases on Shear Bond Strength of Orthodontic Brackets

Objective. The aim of this study was to compare the shear bond strength (SBS) and adhesive remnant index (ARI) scores of no-primer adhesives tested with two different bracket bases. Materials and Methods. 120 bovine permanent mandibular incisors were divided into 6 groups of 20 specimens. Two brackets (ODP) with different bracket bases (anchor pylons and 80-gauge mesh) were bonded to the teeth using a conventional adhesive (Transbond XT) and two different no-primer adhesive (Ortho Cem; Heliosit) systems. Groups were tested using an instron universal testing machine. SBS values were recorded. ARI scores were measured. SEM microphotographs were taken to evaluate the pattern of bracket bases. Statistical analysis was performed. ANOVA and Tukey tests were carried out for SBS values, whereas a chi-squared test was applied for ARI scores. Results. Highest bond strength values were reported with Transbond XT (with both pad designs), Ortho Cem bonded on anchor pylons and Heliosit on 80-gauge mesh. A higher frequency of ARI score of “3” was reported for Transbond XT groups. Other groups showed a higher frequency of ARI score “2” and “1.” Conclusion. Transbond XT showed the highest shear bond strength values with both pad designs.

Epidemiological survey of different clinical techniques of orthodontic bracket debonding and enamel polishing

Objectives: To conduct an epidemiological survey of the orthodontic debonding techniques in Italy, and describe the most commonly used methods to remove the brackets and adhesive from the tooth surfaces. Materials and Methods: A survey consisting of 6 questions about bracket debonding methods and instruments used was emailed to 1000 orthodontists, who were members of the Italian Orthodontics Society (SIDO. Clinicians were characterized by different sex, age, origin, and professional experience. Results: Overall, 267 surveys were returned, representing a response rate of 26.7% of the participants interviewed. The 0.2% of the orthodontists responded, via email, confirming that they were not interested, while 3% of the questionnaires were sent back not completed. The 70.1% of the clinicians interviewed did not return any response. Overall, 64% of SIDO members (orthodontists) did not detect any enamel damage after debonding. The brackets used most frequently (89.14%) in clinical practice were the metal ones. The most commonly used pliers for bracket removal were cutters (37.08%) and bracket removal pliers (34.83%). For adhesive removal, low speed tungsten carbide burs under irrigation were the most widely utilized method for adhesive removal (40.08%), followed by high speed carbide burs (14.19%), and diamond burs (14.19%). The most frequently used instruments for polishing after debonding were rubber cups (36.70%) and abrasive discs (21.35%). The 31.21% of the orthodontists found esthetic enamel changes before bonding versus after debonding. Conclusions: This survey showed the high variability of different methods for bracket debonding, adhesive removal, and tooth polishing. The collected answers indicate that most orthodontists have developed their own armamentarium of debonding and polishing, basing their method on trials and errors.

Opening and closure forces of sliding mechanisms of different self-ligating brackets

Self-ligating brackets engage the wire by means of a slide mechanism. Forces that have to be applied to open and close the sliding mechanism of brackets are still unknown. Objective: The aim of this study was to measure and compare the opening and closure forces of different self-ligating brackets. Material and Methods: Three different stainless steel self-ligating brackets (Carriere LX, Ortho Organizers; F1000, Leone; Damon Q, Ormco) were tested. For each different bracket, 20 maxillary right central incisors and 20 mandibular right central incisors were used. Opening and closure forces were measured using an Instron Universal Testing Machine. Statistical analysis was performed and ANOVA and Tukey tests were carried out. Results: Opening forces were registered between 1.1 N and 5.6 N, whereas closure forces were recorded between 1.57 N and 4.87 N. Significant differences were detected among the different brackets and between the two prescriptions tested. Conclusion: The knowledge of different opening and closure forces of self-ligating brackets can help the orthodontist in the clinical management of these devices.