Attilio Castaldo

Dental malocclusion and body posture in young subjects: a multiple regression study

OBJECTIVES: Controversial results have been reported on potential correlations between the stomatognathic system and body posture. We investigated whether malocclusal traits correlate with body posture alterations in young subjects to determine possible clinical applications. METHODS: A total of 122 subjects, including 86 males and 36 females (age range of 10.8–16.3 years), were enrolled. All subjects tested negative for temporomandibular disorders or other conditions affecting the stomatognathic systems, except malocclusion. A dental occlusion assessment included phase of dentition, molar class, overjet, overbite, anterior and posterior crossbite, scissorbite, mandibular crowding and dental midline deviation. In addition, body posture was recorded through static posturography using a vertical force platform. Recordings were performed under two conditions, namely, i) mandibular rest position (RP) and ii) dental intercuspidal position (ICP). Posturographic parameters included the projected sway area and velocity and the antero-posterior and right-left load differences. Multiple regression models were run for both recording conditions to evaluate associations between each malocclusal trait and posturographic parameters. RESULTS: All of the posturographic parameters had large variability and were very similar between the two recording conditions. Moreover, a limited number of weakly significant correlations were observed, mainly for overbite and dentition phase, when using multivariate models. CONCLUSION: Our current findings, particularly with regard to the use of posturography as a diagnostic aid for subjects affected by dental malocclusion, do not support existence of clinically relevant correlations between malocclusal traits and body posture.

Gingival crevicular fluid protein content and alkaline phosphatase activity in relation to pubertal growth phase.

OBJECTIVE To evaluate gingival crevicular fluid (GCF) protein content and alkaline phosphatase (ALP) activity in growing subjects in relation to stages of skeletal maturation, ie, the growth phase, as prepubertal, pubertal, and postpubertal. SUBJECTS AND METHODS Fifty healthy growing subjects (31 girls and 19 boys; age range, 7.8-17.7 years) were enrolled in this study that followed a double-blind, prospective, cross-sectional design. Collection of GCF was performed at the mesial and distal sites of both central incisors, for the maxilla and mandible. Growth phase was assessed through the cervical vertebral maturation method. GCF parameters were expressed as total protein content, total ALP activity, and normalized ALP activity. RESULTS The total GCF protein content was similar between the different growth phases. On the contrary, the total ALP activity showed a peak for the pubertal growth phase. The normalized GCF ALP activity was only poorly associated with growth phase. No differences were seen between the maxillary and mandibular sites, or between the sexes, for any GCF parameter. CONCLUSIONS The total GCF protein content is not sensitive to the growth phase. However, GCF ALP activity has potential as a diagnostic aid for identification of the pubertal growth phase in individual subjects when expressed as total, but not normalized, values.

Is postural platform suited to study correlations between the masticatory system and body posture? A study of repeatability and a meta-analysis of reported variations.

AIM To evaluate the repeatability of different static posturographic parameters with regard to the analysis of correlations between the masticatory system and body posture. MATERIALS AND METHODS In 15 healthy subjects (26.4±3.7 years, 9 females and 6 males) with no malocclusion, posturographic recordings were carried out by vertical force platform under mandibular rest position (RP) and dental intercuspidal position (ICP). Six different posturographic parameters were recorded at baseline, 30 min, 1 day and 7 days. Repeatability analysis was based on the method of the moment estimator (as percentage over the baseline scores, i.e. method error) and interclass correlation coefficients (ICC). Moreover, a meta-analysis of the variations in posturographic recordings between different occlusal conditions, i.e. RP vs. ICP, from previous studies was also performed. RESULTS Only the sway area and velocity yielded acceptable errors and ICCs up to 14.8% and 0.94, respectively. The spatial parameters, i.e. displacement of the centre of pressure from the theoretical point, performed poorly with lowest errors and greatest ICCs of 149.0% and 0.64, respectively. At the meta-analysis, ten studies were included and a total of 281 variation scores were calculated, with most of the greater and significant variations seen for the spatial parameters. CONCLUSIONS The sway area and velocity show acceptable reliability, but a threshold of 25% should be used as a true variation between two different recording conditions, i.e. RP vs. ICP. Considering that most of the previous results on the relevant correlations between the masticatory system and body posture are based on spatial parameters, with the poorest repeatability, corresponding conclusions should be interpreted with caution.

Combined aging effects of strain and thermocycling on unload deflection modes of nickel-titanium closed-coil springs: An in-vitro comparative study

INTRODUCTION There are no reports on the aging effects of thermocycling of nickel-titanium (NiTi) based coil springs, and few studies have investigated their superelasticity phases in full. In this study, we compared the mechanical properties of NiTi-based closed-coil springs after the combined aging effects of prolonged strain and thermocycling, as a reflection of the clinical situation. METHODS Ninety NiTi-based closed-coil springs were used, 30 each of the following types: (1) Nitinol (3M Unitek, Monrovia, Calif), (2) Ni-Ti (Ormco, Glendora, Calif), and (3) RMO (Rocky Mountain Orthodontics, Denver, Colo); all had similar dimensions (length, 12 mm). In each sample group, 2 equal subgroups of 15 coil springs were extended by either 50% (to 18 mm) or 150% (to 30 mm), immersed in artificial saliva, and kept at 37°C for 45 days. All springs underwent sessions of 1000 thermocycles (1 minute long) from 5°C to 55°C on days 22 and 45. Unload deflection curves from both the 50% and 150% extensions (according to their strain subgroups) were recorded by using a universal testing machine before the strain (baseline) and at both 22 and 45 days, immediately after thermocycling. RESULTS At baseline, the loads exerted by the NiTi-based coil springs varied from 99.8 to 245.1 gf for the RMO (50% strain) and Ni-Ti (150% strain) groups. Statistically significant, although small, differences were seen at each time point in both the 50% and 150% strain subgroups; generally, the highest and lowest values were recorded in the Ni-Ti and Nitinol groups (all, P <0.001). Only the Nitinol coil-spring group showed an acceptable superelasticity phase. The strain and thermocycling did not dramatically change the deactivation forces of any coil springs. CONCLUSIONS NiTi-based closed-coil springs might not have a superelasticity phase, and prolonged strain and thermocycling do not produce clinically relevant alterations in their deactivation forces.

Diagnostic reliability of the cervical vertebral maturation method and standing height in the identification of the mandibular growth spurt

OBJECTIVE To evaluate the capability of both cervical vertebral maturation (CVM) stages 3 and 4 (CS3-4 interval) and the peak in standing height to identify the mandibular growth spurt throughout diagnostic reliability analysis. MATERIALS AND METHODS A previous longitudinal data set derived from 24 untreated growing subjects (15 females and nine males,) detailed elsewhere were reanalyzed. Mandibular growth was defined as annual increments in Condylion (Co)-Gnathion (Gn) (total mandibular length) and Co-Gonion Intersection (Goi) (ramus height) and their arithmetic mean (mean mandibular growth [mMG]). Subsequently, individual annual increments in standing height, Co-Gn, Co-Goi, and mMG were arranged according to annual age intervals, with the first and last intervals defined as 7-8 years and 15-16 years, respectively. An analysis was performed to establish the diagnostic reliability of the CS3-4 interval or the peak in standing height in the identification of the maximum individual increments of each Co-Gn, Co-Goi, and mMG measurement at each annual age interval. RESULTS CS3-4 and standing height peak show similar but variable accuracy across annual age intervals, registering values between 0.61 (standing height peak, Co-Gn) and 0.95 (standing height peak and CS3-4, mMG). Generally, satisfactory diagnostic reliability was seen when the mandibular growth spurt was identified on the basis of the Co-Goi and mMG increments. CONCLUSIONS Both CVM interval CS3-4 and peak in standing height may be used in routine clinical practice to enhance efficiency of treatments requiring identification of the mandibular growth spurt.

Effects of deflection and archwire dimension on the mechanical performance of two self-ligating orthodontic systems.

OBJECTIVES To analyze the effects of archwire deflection and dimension on the mechanical performance of two self-ligating systems, as passive and active ligation designs. MATERIALS AND METHODS An experimental model was used that was designed to resemble the full dental arch and to allow vertical displacement of a canine element. Two self-ligating systems were investigated: 1) a passive system; and 2) an active system, both in combination with three thermoactive NiTi archwires, with round sections of 0.014-in, 0.016-in and 0.018-in. The full loading-unloading cycles consisted of either 3mm or 6mm maximum deflection, performed at 37 °C. During unloading, the deactivation forces and energy were recorded. The ratio between the deactivation and activation energies was used as representative of the mechanical efficiencies of the systems. RESULTS The deactivation force increased in combination with larger archwires and greater deflection. The deactivation energy increased in combination with larger archwires only for the 3-mm deflection cycle, while for the 6-mm deflection cycle, the deactivation energy was not influenced by the archwire dimension, and was not greater than that of the 3-mm deflection cycle. The mechanical efficiency decreased in combination with greater deflection and larger archwires, with a maximum decrease of about 12%. Only minor comparative differences were seen between the systems. CONCLUSIONS The deflection degree and archwire dimension have large effects on the mechanical performance of self-ligating systems.