The mandibular muscles in contemporary orthodontic practice: a review.

It is widely accepted that all dentists should have a thorough understanding of the muscles involved in moving or stabilizing the mandible. However, there is still much discussion regarding the influence of the mandibular muscles on normal facial growth and dental development, as well as on orthodontic treatment and post-treatment stability. Potential patients with different underlying vertical muscle patterns will have differences in the expected directions of future mandibular growth, lateral profile shape, facial and arch widths and vertical occlusal relationships. In turn, thorough diagnoses are likely to lead to differences in individual aims and objectives, treatment plans, timing of commencement, mechanical design, lateral profile and smile-aesthetics outcomes, choice of retention and plans for long-term maintenance. The potential influence of the mandibular muscles on normal morphologic variation and the soft tissue implications on contemporary orthodontic treatment and stability will be addressed in this review.

Effect of different orthodontic adhesive removal techniques on sound, demineralized and remineralized enamel.

BACKGROUND: The aim of this in vitro study was to determine the effect of four different orthodontic adhesive removal techniques on sound, demineralized and remineralized enamel. METHODS: Composite resin adhesive was bonded to 100 teeth which were divided into four groups with each comprising five sound teeth and 20 teeth with demineralized and remineralized lesions adjacent to the adhesive. Adhesive was removed with either: (1) slow speed bur (SS); (2) high speed bur (HS); (3) aluminium oxide disc (DC); or (4) ultrasonic scaler (US). Damage to the enamel was assessed using white light profilometry, digital photography and scanning electron microscopy. RESULTS: The least to greatest mean depth of damage with the four different adhesive removal techniques to sound enamel was DC = SS < US = HS and to demineralized and remineralized enamel were DC < HS < US = SS. Sound enamel experienced the least amount of damage. Remineralization prior to adhesive removal significantly reduced the amount of damage produced by all techniques compared with demineralized enamel. Discs were the least damaging to demineralized and remineralized enamel compared with the other removal techniques. CONCLUSIONS: When demineralization was present discs were found to be the least damaging adhesive removal technique and remineralization further reduced the amount of enamel damage.

Prevention of white spot lesions in orthodontic practice: a contemporary review.

The development of white spot demineralization associated with fixed appliance orthodontic treatment is a significant clinical problem. Both established and experimental methods for prevention of such lesions in day-to-day clinical practice are presented and discussed.

Is orthodontic treatment without premolar extractions always non-extraction treatment?

While it is common in contemporary orthodontic and orthopaedic treatment to commence treatment for many growing patients during the mixed-dentition, the creation of anterior space, often involving the attempted distalization or holding-back of the upper and lower permanent molar teeth has been shown to commonly result in posterior space deficiencies. Although the extractions of permanent premolar teeth may have been avoided, the developing second and third permanent molars are often affected, so that third molar impaction results in many cases. This is not to say that orthodontic treatment carried-out without premolar extractions is not ideal in many cases, but on the available evidence, so-called absolute 'non-extraction' protocols should be questioned, so that both the dental profession and the public at large are not misled.

The role of the divine proportion in the esthetic improvement of patients undergoing combined orthodontic/orthognathic surgical treatment.

This study was designed to investigate the changes in a number of facial proportions as a result of combined orthodontic/orthognathic surgical treatment. According to some authors, in beautiful faces, the values of the proportions measured are likely to approximate the divine proportion (1.618:1). The hypothesis for this study was that, as a result of treatment, the faces of patients in the sample would be more esthetic and therefore the measured proportions would be closer to the divine proportion than they were before treatment. Forty-six patients were included in the sample. Pre- and posttreatment photographs were each given a score (out of a possible 100) by 12 judges using a visual analog scale. Judges were shown frontal and profile views simultaneously. Ten ratios were measured from pre- and posttreatment lateral cephalograms, and 11 were measured from the frontal photos. Pearson's correlation coefficient was used to determine the correlation between changes in esthetic rating and changes in the measured proportions. No correlations were found between changes in esthetic ratings and changes in the proportions. While most subjects were considered more esthetic after treatment than before, the proportions were equally likely to move away from or toward the divine proportion. For this reason, if it is to be used as an aid to orthodontic/orthognathic treatment planning, the divine proportion should perhaps be used along with other methods of anteroposterior and vertical cephalometric and facial assessment.

An occlusal and cephalometric analysis of maxillary first and second premolar extraction effects.

The purpose of this study was to examine dimensional changes in the maxillary arch following the extractions of maxillary first or second premolars. Pre- and posttreatment records of 71 patients treated by one experienced orthodontist were randomly selected from completed premolar extraction cases. Forty-five patients involved the extraction of maxillary first premolars; of these, 15 also had extractions of mandibular first premolars and 30 had extractions of mandibular second premolars. Twenty-six patients involved the extraction of maxillary second premolars, and all of these also had extractions of mandibular second premolars. Pretreatment factors that seemed to suggest a basis for the extraction choice in this sample included incisal overjet, molar relationship, and maxillary incisor protrusion. Mean reductions with treatment in the anteroposterior arch dimension were similar within all premolar extraction groups. There was evidence of greater mean maxillary intermolar-width reduction following the extractions of maxillary second premolars than following extractions of maxillary first premolars. Greater mean maxillary incisor retraction was found in the maxillary first premolar extraction group than in the maxillary second premolar group. A wide range of individual variation in incisor and molar changes did, however, accompany treatment involving both maxillary premolar extraction sequences.

An occlusal and cephalometric analysis of lower first and second premolar extraction effects.

This study was designed to examine lateral cephalometric and arch dimensional changes that occur in the mandibular arch during orthodontic treatment involving the extractions of various premolars. Pretreatment and posttreatment records of 73 patients were chosen at random from completed cases in the practice of one experienced orthodontist. Eighteen involved the extraction of lower first premolars, and 55 involved the extraction of lower second premolars. Of these 55, 29 involved the extraction of upper first premolars and 26 involved the extraction of upper second premolars. In the lower first premolar group, however, all 18 involved the extraction of upper first premolars. Males and females were evenly represented in the 3 subgroups. Pretreatment factors that suggested a basis for the extraction choice in this group of patients were found to include incisal overjet, molar relationship, and underlying vertical facial pattern. A wide variety of arch dimensional changes was found with different lower premolar extraction patterns. There was evidence, however, of more intermolar arch width reduction after the extraction of lower second premolars than lower first premolars. Orthodontic treatment with the extraction of premolars did not consistently cause a retrusive effect on the incisors. In fact, instances of proclination of the incisors occurred within all of the extraction groups. A large amount of individual variation in incisor and molar changes accompanied treatment involving all lower premolar extraction patterns.

Realistic late-mixed dentition treatment of Class I and II malocclusions.

In contemporary orthodontic practice, a large number of Class I and Class II patients, with and without crowding, are treated without premolar extractions. A wide range of philosophies and devices have been introduced with the aims of providing more space within the arches for the accommodation of the teeth, and influencing the relationships between the upper and lower arches. Some of these philosophies and devices are new--others have been recycled from previously-used models, which may or may not have been discarded for a number of reasons. Much descriptive and anecdotal material has been presented to support these developments. There have also been isolated studies of the effects of various mechanical component parts on dentofacial structures, some using homogenous subject-material, others using quite non-homogenous material. Little quantitative assessment has been made, however, of the effects of holding the E-spaces, uprighting the permanent first molars and redirecting the erupting permanent second molars, on attempts to provide sufficient space within the arches for alignment and levelling, correcting Class II anterior and posterior relationships and finding space for the uncomplicated eruption of the third molars. In addition, none of these space-holding or gaining effects has really been assessed alongside the effects of various attempts to orthopaedically-modify maxillary growth, if necessary, as the mandible naturally moves forward with its dentition. If a likely range of growth and treatment effects could be demonstrated in large relatively homogenous samples, one would have gone someway towards explaining the anecdotal phrase "unlocking the malocclusion", which has so often appeared in the literature. One might also have challenged another widely-held concept--that, when relieving crowding within the dental arches, one is either an extractionist or an expansionist. It might then be possible to show that, in a growing patient with a Class I or II malocclusion, crowding may well be relieved by providing space within the arches (perhaps, at the expense of the third molars), and by allowing the mandible and its dentition to move forward with growth, while forward movement of the maxilla and its dentition is inhibited.

Incisal changes and orthodontic stability.

Lateral cephalograms and study casts of 55 patients were evaluated to determine if any relationships exist among incisal positions and angulations, changes in positions and angulations, and long-term occlusal stability. No significant relationships could be found between long-term changes occurring in a number of commonly used incisal measurements and end-of-treatment incisal positions, changes in incisal positions during treatment, or long-term changes in the facial axis angle, ANB angle, or weighted PAR score. Long-term incisal changes occurring in individual patients were not necessarily associated with negative occlusal changes. Since incisal positions usually change in the long-term, it is suggested that the use of published norms or recommended absolute goals for end-of-treatment incisal positions be used more as general functional and esthetic clinical guides, rather than as predictors of stability.

Bond strengths of orthodontic brackets to restorative resin composite surfaces.

In orthodontic practice, it is not uncommon to bond brackets to resin composite restorations. With this in mind, this study was designed to compare first the shear/peel strengths of metal, ceramic and polycarbonate brackets bonded to microfilled resin composite (RC), using either a light-cured resin-modified glass ionomer cement (Fuji Ortho LC), a chemical-cured composite (System 1+) or a light-cured composite adhesive (Transbond XT); and then to examine the effects of thermocycling on the shear/peel strengths of these systems. Four different brackets were used: two stainless steel (Victory and Optimesh), one ceramic (Transcend 6000) and one polycarbonate (Spirit MB). Seventy-two specimens of each bracket were divided into three groups for bonding with one of the three adhesives. Half the specimens from each group were also thermocycled. Mean shear/peel bond strengths were found to be significantly different for the four different brackets, although not influenced by the three adhesives used within each group. All groups were found to have clinically-acceptable mean bond strengths, except for Spirit MB-System 1+. After thermocycling, both Optimesh-Transbond XT and Victory-System 1+ groups showed superior mean bond strengths (26.8 and 24.4 MPa, respectively) when compared with all other groups (p < 0.05). Applying the Weibull survival analysis for groups utilising Victory, Transcend 6000 and Spirit MB brackets, those with 90 per cent or greater probabilities of survival included Victory-System 1+, Transcend 6000-Fuji Ortho LC, Victory-Fuji Ortho LC and Spirit MB-Transbond XT groups. In all groups, bond failure was mainly (64 per cent) cohesive within the RC restorative surface. The thermocycled Spirit MB-Transbond XT group had the highest frequency of undamaged RC failure interfaces. Despite the focus of this study being on bond strength and the potential for surface damage, it was noted that these properties should always be considered alongside other factors such as the strength of the bracket itself, friction within the bracket slot, patients' wishes, cost of the materials and the presenting malocclusion.

Antiviral properties of 3-quinolinecarboxamides: a series of novel non-nucleoside antiherpetic agents.

Novel antiherpetic 3-quinolinecarboxamides were discovered as part of a drug discovery program at Sterling Winthrop Inc. A major goal of this research was to identify novel non-nucleoside agents possessing activity against acyclovir resistant herpes simplex virus. From screening compound libraries in an HSV-2 plaque reduction assay, 1-ethyl-1,4-dihydro-4-oxo-7-(4-pyridinyl)-3-quinolinecarboxamide (1) emerged as an attractive lead structure. By modifying the quinoline ring at the 1-, 2-, 3-, 4-, and 7-positions, analogues were identified that have up to 5-fold increased in vitro potency relative to acyclovir. In a single dose mouse model of infection the 1-(4-FC6H4) analogue 17, one of the most potent derivatives in vitro, displayed comparable oral antiherpetic efficacy to acyclovir at 1/16 the dose; in a multiple dose regimen, however, it was 2-fold less potent. Mechanism of action studies indicate that these new compounds interact with a different, as yet undefined, molecular target than acyclovir.

The use of a simple functional appliance as an adjunct to fixed appliance orthodontic treatment. Case reports.

Three clinical case studies are presented to demonstrate the use of a simple functional appliance in orthodontic situations not covered by traditionally-accepted dental and skeletal indications. In each case, the appliance was used to reduce the severity of the malocclusion, before a routine fixed-appliance detailing phase.

Cyclic variations of 3-quinolinecarboxamides and effects on antiherpetic activity.

Supported by the antiherpetic properties of 3-quinolinecarboxamides and the importance of the planar intramolecular H-bonded beta-keto amide pharmacophore, a series of novel conformationally rigid analogues that contain a heterocyclic bridge between the 3- and 4-positions of the quinoline ring have been evaluated. Two isoxazolo-fused derivatives 17 and 23 displayed good in vitro antiherpetic potency that was similar to that of 1, the 3-quinolinecarboxamide that served as the comparison structure for this study. The pyrazolo, pyrrolo, and pyrimido derivatives showed considerably less or no activity. In vitro activity did not translate to in vivo efficacy. For 17, the lack of in vivo activity is likely a consequence of insufficient plasma drug levels (both Cmax and duration) in mice relative to the MIC versus HSV-2.

Dissociative experiences of Vietnam veterans with chronic posttraumatic stress disorder.

Interest in dissociation has been renewed, and its relationship to Post-traumatic Stress Disorder is especially intriguing. In this study 57 consecutively admitted chronic, combat-related Posttraumatic Stress Disorder sufferers were grouped by scores on a dissociative scale (Dissociative Experiences Scale). The three groups (high, medium, and low) were compared on personality measures (MMPI basic scales and subscales, and Millon's MCMI), Posttraumatic Stress Disorder measures, and a psychophysiological index of heart rate under baseline trauma conditions. The results showed that the survivors with more dissociative experiences show distinctive and higher symptom levels--excessive fearfulness, symptoms of strange experiences, and high tonic psychophysiological states--as well as greater severity of ratings of Posttraumatic Stress Disorder (on the Mississippi Scale). The discussion addressed the possible role of dissociation in Posttraumatic Stress Disorder.

3-Quinolinecarboxamides. A series of novel orally-active antiherpetic agents.

A series of novel 3-quinolinecarboxamides that are structurally similar to the quinolone class of antibacterial agents possess excellent antiherpetic properties. By modifying the quinoline ring at the 1-, 2-, 3-, and 7-positions, analogues were identified that have up to 5-fold increased HSV-2 plaque-reduction potency relative to acyclovir. In a single-dose mouse model of infection, one of the most potent derivatives in vitro, 1-(4-fluorophenyl)-1,4-dihydro-4-oxo-7-(4-pyridinyl)-3-quinolinecarbo xamide (97), displayed comparable oral antiherpetic efficacy to acyclovir at 1/16 the dose; in a multiple-dose regimen, however, 97 was 2-fold less potent. In mice dosed orally with 97, sustained plasma drug levels were evident that may account for the high efficacy observed. The molecular mechanism of action of these agents is not known; however, based on in vitro studies with acyclovir resistant mutants, it is likely that the mechanism differs from that of acyclovir. In vitro plaque-reduction potency was not generally predictive of oral efficacy in mice. An X-ray crystal structure of 97 corroborated the assignment of structure and provided useful insights as to the effect of conformation on plaque-reduction potency.

Negative parenting behavior, combat exposure, and PTSD symptom severity. Test of a person-event interaction model.

The "personal characteristics" and "extreme event" hypotheses have been proposed as alternative explanations for the development of posttraumatic stress disorder (PTSD) among combat veterans. The person-event interaction model attempts to integrate both perspectives by hypothesizing that premilitary individual vulnerability characteristics play a greater role in influencing risk of PTSD or PTSD symptom severity at lower than at higher levels of exposure to traumatic combat stressors. Focusing on a sample of 57 Vietnam veterans undergoing inpatient treatment for diagnosed PTSD, we assessed this model by examining interactions between negative parenting behaviors in childhood (e.g., inconsistent love) and degree of combat exposure in predicting PTSD symptom severity. Hierarchical regression analyses supported the model, indicating that the father's negative parenting behaviors were more predictive of PTSD symptom severity at relatively lower levels of combat exposure. Implications of the findings for further research on multivariate, interactional models of PTSD etiology among Vietnam combat veterans are discussed.

A short form of the Mississippi Scale for Combat-Related PTSD.

At the present time, The Mississippi Scale for Combat-Related PTSD (Mississippi Scale) is the best paper-and-pencil measure of this disorder. This study carried out a test-retest reliability on 52 chronic Vietnam veterans with PTSD and established three psychometric criteria for item retention in order to establish a short form of the Mississippi Scale. Ten items met these criteria and had a test-retest reliability coefficient of .66 (under the most stringent of conditions, treatment). This 10-item measure (Miss-10) then was applied to 95 new PTSD cases. This scale yielded two factors, guilt and numbing/anger. Discussion addressed its use as part of a screening battery or for monitoring change across time.

Suicidal behavior among chronic Vietnam theatre veterans with PTSD.

Suicidal behavior among Vietnam veterans with chronic Post-traumatic Stress Disorder (PTSD) was evaluated. Sixty chronic PTSD vets admitted to a Specialized PTSD Unit were divided into two groups based on the presence of suicidal behavior: 29 patients in a Suicide Group and 31 in a Non-suicide Group. Subjects were evaluated on symptoms, psychometric measures, military variables, adjustment factors, and pre-military parental patterns of discipline. Results showed that the Suicide Group possessed problems in paternal child-rearing patterns, current adjustment difficulties, and the PTSD symptoms of survival guilt and crying. In a regression analysis, paternal inconsistency of love, survivor guilt, and tendency to cry, in addition to age and sex, accounted for the significant variance of suicidal behavior.

Alexithymia among Vietnam veterans with posttraumatic stress disorder.

The authors studied 227 inpatients from a large Veterans Administration Medical Center to evaluate whether alexithymia is associated with posttraumatic stress disorder (PTSD) and to assess the validity of the Minnesota Multiphasic Personality Inventory (MMPI) alexithymia scale. Three groups--a carefully diagnosed PTSD group (N = 76), an alcohol abuse group (N = 76), and a general psychiatric group (N = 75)--were given a battery of psychological tests, including the MMPI, the Millon Clinical Multiaxial Inventory, and the Beck Depression Inventory, along with several cognitive measures. PTSD veterans were also evaluated on psychophysiologic indices (including a stressor) and on their subjective ratings to these indices. Results showed that alexithymia was more characteristic of PTSD patients than of the other groups. Also, alexithymia was inversely related to heart rate. Alexithymia was not significantly correlated with the subjective experience of stressors. The authors discuss the importance of the construct of alexithymia among PTSD patients and recommend the use of the alexithymia scale for these patients. The independence of this measure from the psychophysiologic condition of hyperarousal and the subjective experience of this state were also addressed.