Michele D'Attilio

A new one-step dental flowable composite for orthodontic use: an in vitro bond strength study.

A new flowable composite, Denfil Flow, has shown an acceptable shear bond strength for bonding orthodontic brackets, when used with an intermediate, unfilled, low-viscosity resin. According to the manufacturer, it also shows a good viscosity for use with no preliminary adhesive. This could reduce the total time of bonding procedure while maintaining clinically useful bond strength. The aim of the current research was to assess this property. Eighty extracted human premolars were randomly divided into four equal groups. Stainless steel brackets were bonded to etched enamel using (1) Denfil Flow, (2) a traditional flowable composite (Dyract Flow), (3) Denfil Flow composite resin and an intermediate liquid resin, and (4) Transbond XT adhesive. Debonding was performed with a shearing force. The residual adhesive on the enamel surface was evaluated using the adhesive remnant index. The bond strength of Denfil Flow (34.8 MPa) showed no significant difference with the other control groups and was clinically acceptable. Denfil Flow and Dyract Flow tended to display cohesive failure within the adhesive. Denfil Flow can be used without liquid resin to reduce the bonding procedure time while maintaining acceptable bond strength. Further studies are required to evaluate the enamel surface of the teeth after the same polishing procedure in the four groups.

Surface electromyographic patterns of masticatory, neck, and trunk muscles in temporomandibular joint dysfunction patients undergoing anterior repositioning splint therapy.

The aim of this study was to investigate the surface electromyographic (sEMG) activity of neck, trunk, and masticatory muscles in subjects with temporomandibular joint (TMJ) internal derangement treated with anterior mandibular repositioning splints. sEMG activities of the muscles in 34 adult subjects (22 females and 12 males; mean age 30.4 years) with TMJ internal derangement were compared with a control group of 34 untreated adults (20 females and 14 males; mean age 31.8 years). sEMG activities of seven muscles (anterior and posterior temporalis, masseter, posterior cervicals, sternocleidomastoid, and upper and lower trapezius) were studied bilaterally, with the mandible in the rest position and during maximal voluntary clenching (MVC), at the beginning of therapy (T0) and after 10 weeks of treatment (T1). Paired and Students t-tests were undertaken to determine differences between the T0 and T1 data and in sEMG activity between the study and control groups. At T0, paired masseter, sternocleidomastoid, and cervical muscles, in addition to the left anterior temporal and right lower trapezius, showed significantly greater sEMG activity (P = 0.0001; P = 0.0001; for left cervical, P = 0.03; for right cervical, P = 0.0001; P = 0.006 and P = 0.007 muscles, respectively) compared with the control group. This decreased over the remaining study period, such that after treatment, sEMG activity revealed no statistically significant difference when compared with the control group. During MVC at T0, paired masseter and anterior and posterior temporalis muscles showed significantly lower sEMG activity (P = 0.03; P = 0.005 and P = 0.04, respectively) compared with the control group. In contrast, at T1 sEMG activity significantly increased (P = 0.02; P = 0.004 and P = 0.04, respectively), but no difference was observed in relation to the control group. Splint therapy in subjects with internal disk derangement seems to affect sEMG activity of the masticatory, neck, and trunk muscles.

Shear bond strength, bond failure, and scanning electron microscopy analysis of a new flowable composite for orthodontic use.

A new dental flowable composite, Denfil Flow, was evaluated for the bonding of orthodontic brackets by determining its shear bond strength (SBS) and the mode of bond failure after debonding. Eighty extracted human premolars were divided into two equal groups. Metal brackets were bonded to etched enamel using a composite resin control (Transbond XT) or Denfil Flow. After 72 hours of incubation in saline solution at 37 degrees C, debonding was performed with a shearing force. The SBS and the mode of bond failure were examined. In addition, representative samples from each group were examined by scanning electron microscopy (SEM). No significant difference was observed in the SBS between the groups, and a clinically acceptable SBS was found for the two adhesives. Bond failures occurred mostly in the bracket-adhesive interface, without significant differences between the groups. At SEM analysis, Denfil Flow showed a greater frequency of air bubbles within the resin than did Transbond XT. In conclusion, Denfil Flow displayed the same SBS as traditional composite resins and similar bond failures. Further clinical studies are required.

The Influence of an Experimentally-Induced Malocclusion On Vertebral Alignment in Rats: A Controlled Pilot Study

Abstract There is a growing interest in the relationship between occlusion and posture because of a greater incidence of neck and trunk pain in patients with occlusal dysfunction. The study was designed to verify whether an alteration of the spinal column alignment may be experimentally induced in rats as a consequence of altering dental occlusion and also to investigate whether the spinal column underwent any further changes when normal occlusion was then restored. Thirty rats were divided into two groups. Fifteen (15) rats (test group) wore an occlusal bite pad made of composite resin on the maxillary right first molar for a week (T1). The same rats wore a second composite bite pad for another week on the left first molar in order to rebalance dental occlusion (T2). Fifteen rats were included in an untreated control group. All the rats underwent total body radiographs at T0 (before the occlusal pad was placed), at T1 (one week after application of a resin occlusal bite pad on the maxillary left first molar) and at T2 (one week after application of a second resin occlusal bite pad on the maxillary right first molar). A scoliotic curve developed in all the test rats at T1. There were no alterations of spinal position observed in any of the control rats. Additionally, the spinal column returned to normal condition in 83% of the test rats when the balance in occlusal function was restored. The alignment of the spinal column seemed to be influenced by the dental occlusion.

Role of the friction free distalize appliance (2FDA)PAT in the molar distalization: photoelastic analysis and alkaline-phosphatase (ALP) activity on first molar and bicuspid.

Maxillary molar distalization is an increasingly popular option for the resolution of Class II malocclusions. This study describes the effects of one particular molar distalizing appliance, the Friction Free Distalize Appliance (2FDA), in a sample of 20 consecutively treated and growing patients to verify the osteoblastic activity in the compression and traction sites of both the molars and the bicuspids when used as the anchorage teeth. The 2FDA appliances were constructed utilizing a Nickel Titanium open coil spring of 200 gr force in order to distalize the maxillary first molar. The reaction force was controlled utilizing the principle of low/free friction. The results show that the resin around the root of the bicuspid did not discolour at all, which indicates an absence of a force load. On the other hand, on the molar, the resin around the root of the molar became discoloured due to the fact that an orthodontic force was involved with the tooth. To better understand whether the quantity of force that reached the tooth was able to produce osteoblastic recruitment in the sites of tension of the molar and the bicuspid, we quantified an enzyme, the alkaline phosphatase (ALP), present. This measurement allowed us to verify a regular increase of the ALP on the site of molar traction. We also elaborated a mathematical model to evaluate the quantity of force of reaction that produces the device on the bicuspid. Such force results as being 8.34 grams which equals half the pressure of the capillaries of the parodontal ligament (18 grams). The 2FDA appliance compares favourably with other intra-oral distalization devices for the resolution of patients with Class II malocclusions, and is the only distalizing appliance that does not determine osteoclastic/osteoblastic recruitment on the “anchorage tooth”.

Effects of the antigravitary modification of the myotension of asset (MAGMA) therapy on myogenic cranio-cervical-mandibular dysfunction: a longitudinal surface electromyography analysis.

ABSTRACT This study was aimed at evaluating the effects of a novel physiotherapy machine called MAGMA (AntiGravitary Modification of the Myotensions of Asset) on postural and masticatory muscles of subjects with myogenic cranio-cervical-mandibular dysfunction (CMD), by using surface electromyography (sEMG). Fifteen subjects, nine males and six females (mean age 27.6 years), with CMD were included in the study. The bilaterally monitored muscles were: masseter, anterior and posterior temporalis, digastric, posterior cervical, sternocleidomastoid, and upper and lower trapezius. All muscles were monitored at rest, with a second record of maximal voluntary clenching (MVC) for both the masseter and anterior temporalis. Patients were subjected to MAGMA therapy for one session/week of 30 min over ten weeks. The surface EMG activity was recorded twice, at the baseline and at the end of the therapy. After MAGMA therapy, the sEMG activity at rest of the monitored muscles was significantly better when compared to the baseline; the only exception was the anterior and posterior temporalis muscles which did not improve. On the contrary, with the MVC, all the monitored muscles (masseter and anterior temporalis) significantly improved their sEMG activity. Although more investigations are needed, these results indicate that the use of such antigravitary therapy can provide a tool for resolving myogenic CMD.