Biomedical subjects

J Rebellato

Publications and source records attributed to J Rebellato.

11 recordsLinked to original sources

PubMed2000

Effect of argon laser irradiation on shear bond strength of orthodontic brackets: an in vitro study.

Argon lasers, due to their significant time savings over conventional curing lights, are being investigated for use in bonding orthodontic brackets. They are also being investigated for their ability to confer demineralization resistance on enamel. The purpose of this study was to evaluate the effects of argon laser irradiation on bond strength at 3 different laser energies (200, 230, and 300 mW) and at 3 unique time points of laser application (before, during, or after bracket placement). One hundred-fifty human posterior teeth were divided into 9 study groups and 1 control group. After debonding, the adhesive remnant index was scored for each tooth. There was no evidence of an effect of energy level on bond strength, P =.903, or of an interaction between timing of bracket placement and energy level, P =.858. When combining data across energy levels, the mean bond strength was significantly different between all 3 bracket placement groups, P <.001. In addition, the mean bond strength of teeth lased after bonding was significantly higher than the control group, P <.05. There were no statistically significant differences between adhesive remnant index scores among the 10 groups. Lasing the enamel before or after bonding does not adversely affect bond strength. Use of the argon laser to bond orthodontic brackets can yield excellent bond strengths in significantly less time than conventional curing lights, while possibly making the enamel more resistant to demineralization.

Analysis of Variance↗

PubMed1999

Condylar positional changes after mandibular advancement surgery with rigid internal fixation.

The purpose of this retrospective investigation was to describe condylar positional changes in patients after mandibular advancement surgery. By superimposing on clearly identifiable cephalometric landmarks (ie, mandibular symphysis and rigid fixation screws), condylar positional changes from immediately after surgery to orthodontic appliance removal were extrapolated. Although the mandibular symphysis generally moved in either an anterior or posterior direction after surgery, condylar movements were exclusively in an upward vertical direction. Correlations were found between several measured variables, including a tendency for increased superior postsurgical movement of the condyles with increasing magnitudes of surgical advancement of the mandible. This long-term instability of skeletal relationships may be caused by a wide variety of interacting factors and events.

Adolescent↗

PubMed1998

Asymmetric extractions used in the treatment of patients with asymmetries.

Patients with dentoalveolar asymmetries can present some of the most biomechanically challenging situations to the orthodontist. One creative approach for managing dental asymmetries is to extract a combination of teeth that will simplify intra-arch and interarch mechanics. Often this will also reduce the dependency on patient compliance for elastic wear and may even shorten treatment time. Atypical extraction patterns can also be beneficial in the presurgical orthodontic preparation of orthognathic surgery patients. Multiple diagnostic scenarios are discussed, and various treatment plans involving asymmetric extraction patterns are reviewed.

Dental Arch↗

PubMed1998

Orthodontic treatment priority: a comparison of two indices.

Approval for state sponsored funding of orthodontic treatment is often decided using an index of malocclusion. The purpose of this study was to determine whether two indices used for prioritizing patients would identify different groups of individuals qualifying for orthodontic treatment funding approval. In addition, the characteristics of patients approved using different indices were compared. The records of 40 patients previously submitted for state medicaid funding approval were evaluated by three study examiners using two orthodontic treatment priority indices, the Salzmann Handicapping Malocclusion Assessment (Salzmann) and the Index of Orthodontic Treatment Need (IOTN). Comparisons were made between state medicaid and study examiner Salzmann scores, rankings, and funding decisions, and between study examiner Salzmann rankings, IOTN rankings, and funding decisions. Correlation and rank correlation coefficients between the state and study examiners' Salzman scores were high (r = 0.74; p < 0.001, and R = 0.77; p < 0.001). Rank correlation analysis of the study examiners' Salzmann and IOTN values demonstrated a weaker relationship (R = 0.40; p < 0.02). Agreement on funding decisions, evaluated by the Kappa statistic, was greater between the two Salzmann evaluations (K = 0.57) than between the study examiners' Salzmann and IOTN evaluations (K = 0.14). As expected, depending on the method used to determine orthodontic treatment funding priority, different patients were likely to be identified for treatment approval. The characteristics of patients whose treatment was approved was closely related to the criteria defined by the method employed.

Health Care Rationing↗

PubMed1997

Lower arch perimeter preservation using the lingual arch.

The purpose of this investigation was to determine whether the placement of a mandibular lingual arch maintained arch perimeter in the transition from the mixed to the permanent dentition, and if so, whether it was effective at preventing mesial migration of first permanent molars, or whether this migration still occurred en masse, by increased lower incisor proclination. Thirty patients were randomly assigned to either a treatment group (N = 14, mean age = 11.5 years) or a control group (N = 16, mean age = 11.3 years). Study models, cephalograms, and tomograms of the patients, taken at the beginning and at the end of the study period, were examined. Statistically significant differences between groups were found for positional changes of mandibular first molars and incisors, and changes in arch dimensions. The results indicate that the lingual arch can help reduce arch perimeter loss, but at the expense of slight mandibular incisor proclination.

Cephalometry↗

PubMed1997

Variability of facial photographs for use in treatment planning for orthodontics and orthognathic surgery.

Facial photographs are commonly used preoperatively for recording and analyzing skeletofacial and dentofacial deformities prior to orthodontics and/or orthognathic surgery. This study was undertaken to determine the reproducibility of facial photographs over time in any individual patient. Twenty subjects had full-facial frontal and lateral, frontal smile, and lip-to-tooth length (incisor show at rest) photographs taken on 5 different days over a 7- to 14-day period. A total of 18 linear and angular measurements were made on each set of photographs. Standard errors of the 18 measurements over time were generally moderate but varied widely, suggesting that facial photographs have the potential to provide reliable diagnostic information in some cases. In any individual patient, however, there were some variations within measurements that were clinically unacceptable. Measurements made from pictures of the smile were significantly less reliable than those taken at rest, and measurements of vertical head posture and lower lip length were found to be the least reliable. This study suggests that some measurements from facial photographs are generally reproducible over time, but significant individual variations do occur.

Adult↗

PubMed1996

Biomechanical considerations for orthodontic treatment of adults.

Biomechanical modifications made to accommodate orthodontic treatment of adult dentitions are generally minor and adhere to the basic laws of physics as they apply to all orthodontic tooth movement. Some adult presentations necessitate changes in treatment strategy from what would otherwise be employed in adolescent patients to achieve similar goals. In other cases, objective themselves may need to be modified because of a lack of growth potential, constraints of treatment mandated by the patient, or the presence of multiple missing or compromised teeth. The possibilities and limitations of orthodontic and dentofacial orthopedic treatment for adults are usually easier to define before beginning therapy than with adolescent patients because the unknown contribution that growth will make has already been discounted. By planning treatment and mechanotherapy taking into account the individual circumstances that may affect the patient's biological response to treatment, realistic goals of orthodontics can be mutually recognized and agreed on by both the provider and the patient before therapy is initiated.

Adult↗

PubMed1995

Two-couple orthodontic appliance systems utility arches: a two-couple intrusion arch.

The utility arch is a two-couple intrusion arch wire used for control of anterior deep overbite. It is similar to a one-couple intrusion arch in that it is commonly made with rectangular wire, attached to the teeth only at the molars and the incisors and is activated for incisor intrusion by a molar tip back bend. It differs from a one-couple intrusion arch by the insertion of the incisor segment into the incisor brackets. This results in a fixed point of application of the intrusion force anterior to the incisors and, therefore, incisor rotation by the moment of the force. In addition, insertion of the rectangular wire into the incisor brackets usually creates a third-order couple for incisor rotation. Depending on how it is used, the moment of this couple may be activated in either direction and the resulting associated equilibrium forces will either supplement or reduce the vertical equilibrium forces created by the activation bends at the molars.

Dental Stress Analysis↗

PubMed1995

Two-couple orthodontic appliance systems: torquing arches.

Twists placed in an arch wire between incisor brackets are often used in an attempt to obtain root torque. This is only partially effective because of the equal and opposite reciprocals acting on the adjacent teeth. Alternatively, a V-bend in a torquing arch, inserted at only the molar and incisor brackets, may use the bending properties of the arch wire to create dissimilar moments in a two-bracket system. If the greater moment is present at the incisors, all of the incisors are rotated en masse in the same direction, with the associated equal and opposite vertical equilibrium forces directed at the incisors and molars. The lesser moment at the molar also usually has equilibrium forces that may reduce or supplement vertical forces at the molar and incisor depending on the magnitude and direction of the moment present. If the arch wire is unrestrained the resulting tooth movement shows rotation of the incisors around the CRes and movement of the CRes in the direction of the vertical equilibrium force present. The alternative use of a single force to rotate incisor crowns facially results in a reciprocal distal force at the posterior teeth and rotation of the incisors with a center of rotation apical to the CRes.

Dental Stress Analysis↗

PubMed1995

Two-couple orthodontic appliance systems: activations in the transverse dimension.

Partially bracketed arch wires can be activated in the transverse dimension to produce first-order rotations of the molars and constriction or expansion of intermolar width. A 2 x 6 arch wire is ideal for such activations because of the minimal side effects to the anterior teeth. As with other two-couple orthodontic appliance systems, symmetrical V-bends, asymmetrical V-bends and step bends are used to generate moments of the couples whose associated equilibrium forces can be used to produce desired tooth movement.

Cuspid↗

PubMed1995

Two-couple orthodontic appliance systems: transpalatal arches.

The transpalatal arch (TPA) can be activated to deliver a clinically useful array of forces and couples to move and/or rotate maxillary molars in all three planes of space. Changing the palatal arch form can produce expansion or constriction of intermolar width and activation of the inserts of the TPA will produce couples at the molar sheaths. Activations of the inserts to generate couples is possible in all three planes of space in the form of symmetrical V-bends, asymmetrical V-bends, and step bends. Although the associated equilibrium forces of a couple can be the source of clinical surprises, they can also be harnessed to produce favorable tooth movements.

Dental Stress Analysis↗