Antonios H. Mamandras

Cephalometric changes associated with treatment using the activator, the Fränkel appliance, and the fixed appliance

Treatment with the activator, the Fränkel appliance, and the edgewise appliance was compared in three separate groups; each group consisted of twenty-five nonextraction cases of Class II, Division 1 malocclusion. Hard- and soft-tissue profile changes caused by growth and treatment were assessed by means of pretreatment and posttreatment lateral cephalograms. Anterior movement of A point was 1.6 mm more in the activator group than in the fixed-appliance group. The most anterior point on the maxillary incisor moved 1.5 mm more distally in the fixed-appliance sample than in the functional groups. Among the three groups, the activator sample showed the most anterior movement of the mandible (2.3 mm); the fixed group showed the least (0.6 mm). The fixed-appliance group showed more posterior rotation of the mandible than the activator group. However, relative to cranial base, the movement of the mandibular symphysis was not statistically different in the three groups. There were little differences among the treatment groups with regard to changes in the soft-tissue profile. In clinical terms, there was a remarkable similarity in the changes that occurred in the three treatment groups.

Polymerization with the Argon Laser: Curing Time and Shear Bond Strength

The objective of this study was to determine the efficiency of an argon laser in polymerizing a light-cured orthodontic adhesive. Metal brackets were bonded to 185 premolars, divided into 5 different protocol groups of 37 each as follows: light 40-second buccal, light 40-second lingual, laser 5-second lingual, laser 10-second lingual, and laser 15-second lingual. All bonded specimens were placed in distilled water for 30 days at 37 degrees C followed by thermal cycling for 24 hours. Brackets were detached using a shearpeel load delivered by an Instron machine. The site of bond failure was examined under 10x magnification. The difference in the shear-peel bond strength between the light 40-second buccal (13.31 MPa) and the light 40-second lingual (11.95 MPa) groups was not statistically significant. The mean shear-peel bond strengths for the laser cured groups were quite similar for the 5-, 10- and 15-second laser groups (10.86, 11.32, and 10.80 MPa). The difference in mean lingual bond strength between the light 40-second and laser 5-second groups was not statistically significant (t = 1.26; P = .212). The adhesive remnant index analysis revealed principally cohesive bond failures. An increased frequency of enamel fractures at debond was noted in the lingual light-cured and 10-second laser-cured groups, at 35.1% (13/37) and 21.6% (8/ 37), respectively. All other groups displayed enamel fractures of 16.2% (6/37). A 5-second cure using an argon laser produced bond failure loads comparable to those obtained after 40 seconds of conventional light cure, with less than half the frequency of enamel fracture at debond.

Facial growth in females 14 to 20 years of age

The objective of this study was to determine the magnitude and the direction of postpubertal mandibular and maxillary facial growth in females. The sample consisted of 37 untreated subjects who had Class I skeletal and dental characteristics and whose lateral cephalograms were taken at 14, 16, and 20 years of age. Mandibular growth was determined to be significant for the age periods of 14 to 16 years and 16 to 20 years. Overall mandibular growth as measured from Co-Gn was approximately twice that of the overall maxillary growth as measured from Co-A. Correlation analysis revealed a statistically significant relationship between the estimates of incremental mandibular growth from either articulare or condylion. The mandibular growth rate was found to be twice as large for age period 14 to 16 years as for age period 16 to 20 years. The increase in posterior vertical face height was slightly more than the increase in anterior vertical face height. The mandibular plane angle decreased 1.1 degrees during the age period of 14 to 20 years, suggesting a tendency for a closing rotation of the mandible. Mandibular incisors appeared to tip labially with advancing age. Although variable, the potential for significant maxillary and mandibular facial growth in females during late adolescent has been demonstrated.

Linear changes of the maxillary and mandibular lips

This investigation was designed to assess the growth effect on the linear dimensions of human lips from childhood to adulthood. By means of serial computerized cephalometry, the changes in lip length and thickness were studied in 32 untreated male and female subjects from 8 to 18 years of age. It was observed that the maxillary and mandibular lips, under the influence of growth, increase in both dimensions with the advancement of age. During the period studied, the length and thickness of the lips of the male subjects exhibited greater increases both proportionally and numerically than the corresponding dimensions of female lips.

The depth of the mandibular antegonial notch as an indicator of mandibular growth potential

The craniofacial characteristics and growth potential of 25 orthodontically treated patients with deep mandibular antegonial notch were compared with a similar group of 25 shallow notch subjects by the use of longitudinal lateral cephalometric radiographs. Deep notch cases had more retrusive mandibles with a shorter corpus, smaller ramus height, and a greater gonial angle than did shallow notch cases. The lower facial height in the subjects with a deep mandibular notch was found to be longer, and both the mandibular plane angle and facial axis were more vertically directed. During the average 4-year period examined, the deep notch sample experienced less mandibular growth as evidenced by a smaller increase in total mandibular length, corpus length, and less displacement of the chin in a horizontal direction than did the shallow notch sample. The results of this study suggest that the clinical presence of a deep mandibular antegonial notch is indicative of a diminished mandibular growth potential and a vertically directed mandibular growth pattern.

Male postpubertal facial growth in Class II malocclusions

Maxillary and mandibular postpubertal growth changes were assessed from lateral cephalograms taken when subjects were 16 and 20 years of age. The sample consisted of 39 male subjects with no previous orthodontic treatment who exhibited Class II skeletal characteristics. Significant increases in mean maxillary and mandibular measurements were observed over the age period studied. Mean mandibular growth (Co-Gn) was approximately three times that of maxillary growth (Co-A). Total mandibular growth observed between 16 to 20 years of age was approximately 4.3 mm. The mandible appeared to rotate anteriorly superiorly, reflected by a mean reduction in mandibular plane angle of 1.47 degrees and a greater increase in posterior versus anterior face height. There were not statistically significant changes in incisor angulation. Mean growth changes in this Class II sample were comparable to those previously reported for male subjects with Class I malocclusions over the same age period, suggesting a similarity in postpubertal development between these two groups.

The effects of Fränkel II treatment on arch width and arch perimeter

Changes in dental arch width and total arch perimeter in 24 Class II, Division 1 patients treated with the Fränkel II appliance were compared with changes in an untreated control group. Measurements were made on pretreatment and posttreatment plaster casts at three points on each of four maxillary and four mandibular teeth. Increases in width were computed at the occlusal point and compared for the two samples. A significant increase in occlusal arch width for all measures was suggestive of both a minor tipping movement of the maxillary teeth and a bodily movement of the mandibular teeth. Width development in the maxilla was greater than in the mandible. Occlusal arch width increased more in the molar and premolar regions in the maxilla and in the premolar region in the mandible. Wide arches were found to have as much increase as narrow arches. The total arch perimeter decreased significantly less in the treatment sample than in the control sample. The documented gains in arch width and arch perimeter would not be sufficient to relieve severe crowding, but could be useful in avoiding removal of teeth in borderline extraction cases.

Direct bonding to Adlloy-treated amalgam.

The purpose of this study was to test the bond-enhancing effect by modifying amalgam surfaces with Adlloy (a gallium-tin liquid alloy) and bonding brackets by using two different resin systems. Bond strength and location of bond failure was assessed by using (1) Concise (3M Dental Products) and (2) C&B Metabond (Parkell) systems with and without the use of Adlloy alloy. Class V buccal amalgam restorations (n = 132) were subjected to one of two surface treatments: (1) sandblasting or (2) sandblasting plus Adlloy treatment. Mandibular premolar brackets were bonded with Concise composite resin or C&B Metabond (adhesive) to amalgam surfaces. All specimens were stored in 37 degrees C water for 10 weeks and subjected to thermocycling before bond strength testing. The laboratory shear bond strength of Concise material to amalgam was not improved after Adlloy modification. However, Adlloy-treated amalgam significantly increased the laboratory shear bond strength of orthodontic brackets bonded with C&B Metabond material. The majority (58%) of the bond failures of C&B Metabond bonded to non-Adlloy treated-amalgam occurred at the amalgam-adhesive interface, whereas the majority (58%) of the bond failure of C&B Metabond bonded to Adlloy-treated amalgam failed within the adhesive. Fracture within the amalgam during debonding was observed with C&B Metabond bonded to sandblasted amalgam (21%) and Adlloy-treated amalgam (15%). Regardless of Adlloy treatment, C&B Metabond would appear to provide adequate orthodontic bonding to amalgam; however, there may exist a potential risk of amalgam restoration fracture upon debonding.