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Biomedical subjects

James A McNamara

Publications and source records attributed to James A McNamara.

At least 19 recordsLinked to original sources
PubMed2006

Miocene mammal reveals a Mesozoic ghost lineage on insular New Zealand, southwest Pacific.

New Zealand (NZ) has long been upheld as the archetypical example of a land where the biota evolved without nonvolant terrestrial mammals. Their absence before human arrival is mysterious, because NZ was still attached to East Antarctica in the Early Cretaceous when a variety of terrestrial mammals occupied the adjacent Australian portion of Gondwana. Here we report discovery of a nonvolant mammal from Miocene (19-16 Ma) sediments of the Manuherikia Group near St Bathans (SB) in Central Otago, South Island, NZ. A partial relatively plesiomorphic femur and two autapomorphically specialized partial mandibles represent at least one mouse-sized mammal of unknown relationships. The material implies the existence of one or more ghost lineages, at least one of which (based on the relatively plesiomorphic partial femur) spanned the Middle Miocene to at least the Early Cretaceous, probably before the time of divergence of marsupials and placentals > 125 Ma. Its presence in NZ in the Middle Miocene and apparent absence from Australia and other adjacent landmasses at this time appear to reflect a Gondwanan vicariant event and imply persistence of emergent land during the Oligocene marine transgression of NZ. Nonvolant terrestrial mammals disappeared from NZ some time since the Middle Miocene, possibly because of late Neogene climatic cooling.

Animals↗
PubMed2006

A long-term evaluation of the mandibular Schwarz appliance and the acrylic splint expander in early mixed dentition patients.

INTRODUCTION: The aim of this prospective longitudinal clinical study was to evaluate the short-term and long-term changes in dental-arch dimensions in patients treated with either an acrylic splint rapid maxillary expander alone (RME-only) or a rapid maxillary expander combined with a mandibular removable Schwarz plate (RME-Sz) in the early mixed dentition, followed later by fixed appliances in the permanent dentition. METHODS: The dental casts of 27 RME-only patients were compared with those of 23 RME-Sz patients and 16 untreated controls (CTRL) with constricted maxillary arches at 4 times: pretreatment (T1), after expansion but before fixed appliance therapy (T2), after fixed appliance therapy (T3), and at long-term observation (T4). The mean ages for the treated groups were approximately 9 years at T1, 12 years at T2, 14 years at T3, and 20 years at T4. Arch width, arch depth, arch perimeter, and molar angulation were assessed in all subjects at all observation times. T1-T2, T2-T3, T3-T4, and T1-T4 changes were compared statistically in the treated groups with respect to the CTRL. RESULTS: Treatment with an RME-only or an RME-Sz followed by fixed appliances produced significant short-term and long-term increases in maxillary arch widths compared with the CTRL. The RME-Sz led to significantly more favorable results than the RME-only protocol: (1) significantly greater increases in the transverse width of the mandibular arch and mandibular arch perimeter in the long term, and (2) uprighting of the mandibular posterior teeth buccally, thus allowing for an amount of maxillary expansion that was clinically effective for the correction of moderate tooth size-arch size discrepancies. In the overall observation interval, the significant increases in maxillary and mandibular arch perimeters in the RME-Sz group were 3.8 and 3.7 mm, respectively, when compared with the CTRL. The RME-only protocol produced modest long-term increases in maxillary arch perimeter (2.6 mm); the average long-term increase in mandibular arch perimeter (2.0 mm) in the RME-only group was not statistically significant. CONCLUSIONS: The RME-Sz led to significantly more favorable results than the RME-only protocol.

Analysis of Variance↗
PubMed2006

A prospective long-term study on the effects of rapid maxillary expansion in the early mixed dentition.

INTRODUCTION: The aim of this prospective longitudinal clinical study was to evaluate the short-term and long-term changes in dental-arch dimensions in patients treated with the acrylic splint rapid maxillary expander in the early mixed dentition followed by fixed appliances in the permanent dentition. METHODS: The dental casts of 51 consecutively treated patients (TG) were compared with those of 26 untreated controls (CG) at 3 different times: pretreatment (T1), after expansion and fixed appliance therapy (T2), and at long-term observation (T3). The mean ages for the TG were 8 years 10 months at T1, 13 years 10 months at T2, and 19 years 9 months at T3. Arch widths, arch depth, arch perimeter, and molar angulation were assessed in all subjects at all observation times. T1-T2, T2-T3, and T1-T3 changes were compared statistically in the TG with respect to the corresponding CG. RESULTS: Treatment with an acrylic splint RME followed by fixed appliances produced significantly favorable short-term and long-term changes in almost all maxillary and mandibular arch measurements. The amount of change in both maxillary and mandibular intermolar and intercanine widths fully corrected the initial discrepancies. Approximately 4 mm of long-term relative increase in maxillary arch perimeter, and 2.5 mm additional maintenance of mandibular arch perimeter were observed in the TG compared with the CG. CONCLUSIONS: These results suggest that this protocol is effective and stable for the treatment of constricted maxillary arches, and can relieve modest deficiencies in arch perimeter.

Child↗
PubMed2006

Mandibular changes produced by functional appliances in Class II malocclusion: a systematic review.

The aim of this systematic review of the literature was to assess the scientific evidence on the efficiency of functional appliances in enhancing mandibular growth in Class II subjects. A literature survey was performed by applying the Medline database (Entrez PubMed). The survey covered the period from January 1966 to January 2005 and used the medical subject headings (MeSH). The following study types that reported data on treatment effects were included: randomized clinical trials (RCTs), and prospective and retrospective longitudinal controlled clinical trials (CCTs) with untreated Class II controls. The search strategy resulted in 704 articles. After selection according to the inclusion/exclusion criteria, 22 articles qualified for the final analysis. Four RCTs and 18 CCTs were retrieved. The quality standards of these investigations ranged from low (3 studies) to medium/high (6 studies). Two-thirds of the samples in the 22 studies reported a clinically significant supplementary elongation in total mandibular length (a change greater than 2.0 mm in the treated group compared with the untreated group) as a result of overall active treatment with functional appliances. The amount of supplementary mandibular growth appears to be significantly larger if the functional treatment is performed at the pubertal peak in skeletal maturation. None of the 4 RCTs reported a clinically significant change in mandibular length induced by functional appliances; 3 of the 4 RCTs treated subjects at a prepubertal stage of skeletal maturity. The Herbst appliance showed the highest coefficient of efficiency (0.28 mm per month) followed by the Twin-block (0.23 mm per month).

Humans↗
PubMed2006

Treatment effects of a modified quad-helix in patients with dentoskeletal open bites.

INTRODUCTION: The aim of this study was to investigate the effectiveness of a quad-helix/crib (Q-H/C) appliance in a group of growing subjects with thumb-sucking habits and both dental and skeletal open bites. METHODS: The records of 23 subjects treated with Q-H/C appliances were compared with a control group of 23 untreated subjects with similar vertical relationships. Lateral cephalograms were analyzed before treatment (T1; mean age, 8.4 +/- 1.4 years) and immediately after treatment (T2; mean age, 9.9 +/- 1.5 years). Mean duration of treatment was 1.5 +/- 7 months. The T2-T1 changes in the 2 groups were compared with a nonparametric test for independent samples (Mann-Whitney U test). RESULTS: The average increase in overbite during Q-H/C therapy (3.6 mm more than the control group) overcorrected the amount of anterior open bite at T2. However, 4 of 23 subjects did not show positive overbites at T2. Both the maxillary and mandibular incisors had significantly greater lingual inclinations (about 4.0 degrees) associated with greater extrusion (1.4 and 1.0 mm, respectively) in the Q-H/C group than in the control group. In addition, the treated group showed a greater downward rotation (1.2 degrees) of the palatal plane than did the control group. This change was associated with a greater increase in upper anterior facial height (0.7 mm) and a clinically significant reduction in the palatal plane-mandibular plane angle (-1.7 degrees) in the Q-H/C group with respect to the controls. The upper and lower lips showed significant tendencies toward retraction relative to the E-plane in the treated group (2.6 and 2.9 mm, respectively) compared with the controls. CONCLUSIONS: The Q-H/C appliance was effective in correcting the dental open bite in 90% of growing subjects with thumb-sucking habits and dentoskeletal open bites. The Q-H/C protocol produced a clinically significant improvement in the vertical skeletal relationships because of downward rotation of the palatal plane.

Cephalometry↗
PubMed2006

An estimate of craniofacial growth in Class III malocclusion.

OBJECTIVE: To provide an estimate of growth in Class III malocclusion by means of the analysis of a large population of males and females. MATERIALS AND METHODS: The examined sample consisted of pretreatment lateral cephalometric records of 949 (492 females and 457 males) untreated Class III patients of Caucasian ancestry. Cephalometric dentoskeletal measurements at subsequent age periods in Class III subjects were compared with the population values from subjects included in the University of Michigan Growth Study (UMGS) at 11 consecutive age periods (from 6 through 16 years of age), in male and female groups separately. RESULTS: No difference was found between the Class III and normal groups for the sagittal position of the maxilla at any of the age intervals examined. Sagittal mandibular position and dimensions in Class III subjects were consistently larger than in normal subjects, with the interval of largest "increase" in mandibular length occurring on average 1 year later in both female and male Class III subject with respect to subjects with normal occlusion. CONCLUSIONS: Increases in mandibular length were substantially larger in Class III subjects than in subjects with normal occlusion even during the more mature age interval (15 to 16 years). Lower anterior facial height was significantly larger in Class III individuals during the late developmental stages.

Adolescent↗
PubMed2005

Treatment effects of bonded RME and vertical-pull chincup followed by fixed appliance in patients with increased vertical dimension.

INTRODUCTION: The aim of this study was to investigate the effectiveness of vertical-pull chincup (VPCC) therapy during an initial rapid maxillary expansion (RME) phase, followed by a second phase of comprehensive orthodontic therapy in growing subjects with mild-to-severe hyperdivergent facial patterns. METHODS: The records of 29 subjects treated with bonded RME combined with VPCC followed by a fixed-appliance phase with continued use of VPCC were compared with a group of 29 well-matched patients treated with bonded RME only. Lateral cephalograms were analyzed before the start of treatment (T1), before the second phase of treatment (T2), and after the second phase of treatment (T3). Mean age at T1 was approximately 9 years for both groups. Total treatment period (phase 1, interim phase, and phase 2) was 5.7 years for the VPCC group and 6.2 years for the bonded RME-only group. Statistical comparison between the 2 groups was performed by means of independent sample t tests on the T2-T1, T3-T2, and T3-T1 changes. Cervical vertebral maturation stages were assessed at T1, T2, and T3. RESULTS: The VPCC induced significantly smaller increases in mandibular plane angle of about 2 degrees , lower anterior facial height of about 2.5 mm, and total anterior facial height of about 3.5 mm, compared with the RME-only subjects. These outcomes reflect the therapeutic changes that occurred during phase 1 treatment; phase 2 treatment was not associated with any significant difference in treatment response. No statistically significant differences in vertical dentoalveolar changes were concurrent with the vertical skeletal changes in the subjects treated with the VPCC compared with the RME-only group. CONCLUSIONS: The clinical significance of VPCC wear over 2 phases of treatment (5.7 years) appears to be limited. The VPCC was most effective during the initial (RME) phase of treatment and of little benefit during the fixed appliance phase.

Cephalometry↗
PubMed2005

A comparison of two intraoral molar distalization appliances: distal jet versus pendulum.

INTRODUCTION: This study compared the dentoalveolar and skeletal effects on Class II malocclusions of the distal jet with concurrent full fixed appliances and the pendulum appliance both followed by fixed appliances. METHODS: The 2 samples each consisted of 32 subjects (19 girls and 13 boys) with mean ages at the start of treatment of 12 years 3 months in the distal jet group and 12 years 6 months in the pendulum group. The durations of the distalization phase of treatment were 10 months in the distal jet group and 7 months in the pendulum group, and the durations of the second phase of treatment with fixed appliances were 18 months in the distal jet group and 24 months in the pendulum group. Lateral cephalograms were analyzed at 3 observation times: before treatment, after distalization, and after orthodontic treatment. RESULTS: During molar distalization, the pendulum subjects showed significantly more distal molar movement and significantly less anchorage loss at both the premolars and the maxillary incisors than the distal jet subjects. The distal jet used simultaneously with fixed appliances and the pendulum were equal in their ability to move the molars bodily. Very little change occurred in the inclination of the mandibular plane at the end of the 2-phase treatment (less than 1 degrees ) in both groups. At the end of comprehensive treatment, the maxillary first molars were 0.6 mm mesial to their original positions in the distal jet group and 0.5 mm distal in the pendulum group. Nevertheless, total molar correction was identical in the 2 groups (3.0 mm), and both appliances were equally effective in achieving a Class I molar relationship. Simultaneous edgewise orthodontic treatment during molar distalization in the distal jet group shortened the overall treatment time but produced significant flaring of both maxillary and mandibular incisors at the end of treatment. The impact on the soft tissue profile was minimal with both appliances.

Adolescent↗
PubMed2005

A prospective study of the short-term treatment effects of the acrylic-splint rapid maxillary expander combined with the lower Schwarz appliance.

This prospective clinical study evaluated the short-term treatment effects of acrylic-splint rapid maxillary expander in conjunction with lower Schwarz appliance (RME-Sz) therapy to the acrylic-splint rapid maxillary expansion alone (RME-only group). Pretreatment and posttreatment lateral cephalograms were analyzed for 25 RME patients and 19 RME-Sz patients. The average time between films ranged between nine and 12 months. Statistical comparisons of the treatment changes in the RME-only and RME-Sz groups were performed by means of independent sample t-tests (P < .05). The largest difference between the two groups was in lower anterior facial height (LAFH). The normally occurring increase in LAFH was not observed in the RME-only group during the treatment period, indicating that the acrylic-splint expander had a posterior "bite block effect" on the developing craniofacial complex. LAFH increased by 1.7 mm in the RME-Sz group, a value similar to that observed in untreated individuals. Slight forward displacement of the maxilla was observed when RME was used alone, and the sagittal position of the maxilla remained unchanged in the RME-Sz group. A significant amount of intrusion of the maxillary molars (-0.8 mm) was noted in the RME-only group, whereas the maxillary molars were prevented from erupting in the RME-Sz group. The lower dentition showed a significantly greater amount of extrusion in the RME-Sz group than in the RME-only group. Finally, the Sz appliance prevented the mesial movement of the lower molars during the treatment period.

Acrylic Resins↗
PubMed2005

Gender differences in Class III malocclusion.

This study evaluated gender differences in the cephalometric records of a large-scale cross-sectional sample of Caucasian subjects with Class III malocclusion at different developmental ages. The purpose also was to provide average age-related and sex-related data for craniofacial measures in untreated Class III subjects that are used as reference in the diagnostic appraisal of the patient with Class III disharmony. The sample examined consisted of 1094 pretreatment lateral cephalometric records (557 female subjects and 537 male subjects) of Caucasian Class III individuals. The age range for female subjects was between three years six months and 57 years seven months. The male subject group ranged from three years three months to 48 years five months. Twelve age groups were identified. Skeletal maturity at different age periods also was determined using the stage of cervical vertebral maturation. Gender differences for all cephalometric variables were analyzed using parametric statistics. The findings of the study indicated that Class III malocclusion is associated with a significant degree of sexual dimorphism in craniofacial parameters, especially from the age of 13 onward. Male subjects with Class III malocclusion present with significantly larger linear dimensions of the maxilla, mandible, and anterior facial heights when compared with female subjects during the circumpubertal and postpubertal periods.

Adolescent↗
PubMed2005

Short-term treatment effects produced by the Herbst appliance in the mixed dentition.

This prospective clinical investigation evaluates the dentoalveolar and skeletal cephalometric changes produced by the Herbst appliance during treatment of mixed dentition patients with Class II division 1 malocclusion. Thirty individuals (15 male and 15 female individuals; initial mean age nine years 10 months) were treated with the Herbst appliance for a period of 12 months. For comparison, the records of 30 untreated Class II children (15 boys, 15 girls; initial mean age nine years eight months) were followed without treatment for a period of 12 months. The results indicated that the treatment effects produced in the mixed dentition patients were primarily dentoalveolar in nature. The mandibular incisors were tipped labially, and the maxillary incisors were retruded; a significant increase in mandibular posterior dentoalveolar height occurred, and there was a restriction in the vertical development of the maxillary molars. There was no difference in the forward growth of the maxilla between the two groups. In comparison with the controls, however, the Herbst treatment produced a modest but statistically significant increase in total mandibular length. This increase in total mandibular length, however, was less than that observed in adolescent Herbst patients in other studies.

Cephalometry↗
PubMed2004

Cephalometric variables predicting the long-term success or failure of combined rapid maxillary expansion and facial mask therapy.

The aim of this study was to select a model of cephalometric variables to predict the results of early treatment of Class III malocclusion with rapid maxillary expansion and facemask therapy followed by comprehensive treatment with fixed appliances. Lateral cephalograms of 42 patients (20 boys, 22 girls) with Class III malocclusion were analyzed at the start of treatment (mean age 8 years 6 months +/- 2 years, at stage I in cervical vertebral maturation). All patients were reevaluated after a mean period of 6 years 6 months (at stage IV or V in cervical vertebral maturation) that included active treatment plus retention. At this time, the sample was divided into 2 groups according to occlusal criteria: a successful group (30 patients) and an unsuccessful group (12 patients). Discriminant analysis was applied to select pretreatment predictive variables of long-term treatment outcome. Stepwise variable selection of the cephalometric measurements at the first observation identified 3 predictive variables. Orthopedic treatment of Class III malocclusion might be unfavorable over the long term when a patient's pretreatment cephalometric records exhibit a long mandibular ramus (ie, increased posterior facial height), an acute cranial base angle, and a steep mandibular plane angle. On the basis of the equation generated by the multivariate statistical method, the outcome of interceptive orthopedic treatment for each new patient with Class III malocclusion can be predicted with a probability error of 16.7%.

Adolescent↗
PubMed2004

A cephalometric comparison of treatment with the Twin-block and stainless steel crown Herbst appliances followed by fixed appliance therapy.

This study compared the effects of 2 treatment protocols for correcting Class II disharmony. The first phase of treatment consisted of functional jaw orthopedics with either the Twin-block or the stainless-steel crown Herbst appliance; the second phase consisted of comprehensive fixed-appliance therapy in both protocols. Each of the 2 samples comprised 28 consecutively treated Class II patients. The mean age at the start of treatment was approximately 12 years, and the mean age at the end of the treatment was approximately 14.5 years in both groups. The duration of the treatment phase with the functional appliance was approximately 13 months, and the duration of fixed-appliance therapy was approximately 15 months in both groups. The sex distribution was identical in the 2 groups. Lateral cephalograms were analyzed at the start of treatment (T1) and at the end of the overall treatment protocol (T2). Nonparametric statistics were used for comparisons of starting forms and of the T1-T2 changes between the 2 treatment groups. The stainless-steel crown Herbst appliance and the Twin-block appliance produced very similar therapeutic modifications in Class II patients, although the Twin-block group exhibited almost 2 mm greater correction of the maxillomandibular differential than did the crown Herbst group. The treatment effects of both protocols led to a normalization of the dentoskeletal parameters at the end of the overall treatment period. Twin-block therapy also induced a greater increase in the height of the mandibular ramus (posterior facial height). Overall, only minor differences were detected in the treatment and posttreatment effects of a compliance-free (crown Herbst) and a noncompliance-free (Twin-block) appliance for correcting Class II disharmony.

Adolescent↗
PubMed2004

Postpubertal assessment of treatment timing for maxillary expansion and protraction therapy followed by fixed appliances.

In this cephalometric investigation, we evaluated the correction of Class III malocclusion in subjects who had attained postpubertal skeletal maturity and considered whether treatment timing influenced favorable craniofacial modifications. All subjects (n = 50) were treated with an initial phase of rapid maxillary expansion and protraction facemask therapy, followed by a second phase of preadjusted edgewise therapy. The treated sample was divided into an early treated group (early mixed or late deciduous dentition, 33 subjects) and a late treated group (late mixed dentition, 17 subjects). Mean treatment duration times were 7 years 2 months for the early treatment group and 4 years 5 months for the late treatment group. The treated patients were matched to untreated controls (early control group, 14 subjects; late control group, 10 subjects) on the basis of race, sex, mean age at first observation, mean age at second observation, mean observation intervals, and type of malocclusion. A modified version of Johnston's pitchfork analysis, with additional angular and linear measures for mandibular size and shape and for vertical skeletal relationships, was performed. Analysis of variance was used to evaluate the difference in means for each cephalometric variable in the treated groups compared with the corresponding control groups. The findings showed that orthopedic treatment of Class III malocclusion was more effective when it was initiated at an early developmental phase of the dentition (early mixed or late deciduous) rather than during later stages with respect to untreated Class III control groups. Patients treated with rapid maxillary expansion and facemask therapy in the late mixed dentition, however, still benefited from the treatment, but to a lesser degree. Early treatment produced significant favorable postpubertal modifications in both maxillary and mandibular structures, whereas late treatment induced only a significant restriction of mandibular growth. Significant changes in mandibular size were associated with significant changes in mandibular shape only in early treated subjects. The main contribution to overall occlusal correction was related to skeletal modifications rather than dental changes in both early and late treated groups.

Adolescent↗
PubMed2004

A long-term study on the expansion effects of the cervical-pull facebow with and without rapid maxillary expansion.

This study evaluates the long-term stability of maxillary expansion achieved by widening the inner bow of a facebow, with or without concurrent rapid maxillary expansion (RME) (Haas type), followed by treatment with fixed edgewise appliances. The parent sample included 154 nonextraction patients who started their orthodontic treatment during a defined time period. The exclusion criteria reduced the number of patients to 61 in the cervical-pull facebow group (CFB) and 41 in the RME-CFB group. All subjects were in the late-mixed to early-permanent dentition stage at the start of treatment. Dental casts were measured using a digital imaging system at four different times: start of treatment (T1), end of active treatment (T2), end of retention (T3), and postretention follow up (T4). The RME-CFB protocol produced a greater increase in maxillary arch width (6.1 mm) than did the CFB protocol (4 mm). The RME-CFB protocol provided greater net maxillary arch perimeter increase than did expansion with an inner bow of a cervical facebow. The RME-CFB group had three mm more arch perimeter 10 years after treatment completion than did the CFB group. The stability of expansion achieved with an inner bow of a facebow was equal to that achieved with a Haas-type RME appliance. Both expansion protocols retained 90% of the initial intermolar expansion 15 years after expansion.

Adolescent↗
PubMed2003

Long-term effectiveness and treatment timing for Bionator therapy.

The aim of the present investigation was to provide information about the long-term effects and optimal timing for class-II treatment with the Bionator appliance. Lateral cephalograms of 23 class-II patients treated with the Bionator were analyzed at three time periods: T1, start of treatment; T2, end of Bionator therapy; and T3, long-term observation (after completion of growth). T3 includes a phase with fixed appliances. The treated sample was divided into two groups according to their skeletal maturity as evaluated by the cervical vertebral maturation (CVM) method. The early-treated group (13 subjects) initiated treatment before the peak in mandibular growth, which occurred after completion of Bionator therapy. The late-treated group (10 subjects) received Bionator treatment during the peak. The T1-T2, T2-T3, and T1-T3 changes in the treated groups were compared with changes in control groups of untreated class-II subjects by nonparametric statistics (P < .05). The findings of the present study on Bionator therapy followed by fixed appliances indicate that this treatment protocol is more effective and stable when it is performed during the pubertal growth spurt. Optimal timing to start treatment with the Bionator is when a concavity appears at the lower borders of the second and the third cervical vertebrae (CVMS II). In the long-term, the amount of significant supplementary elongation of the mandible in subjects treated during the pubertal peak is 5.1 mm more than in the controls, and it is associated with a backward direction of condylar growth. Significant increments in mandibular ramus height also were recorded.

Activator Appliances↗