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In utero fracture and malunion of long bones is a rare condition in horses. Most foals with in utero fractures are aborted, and the identification of a fetal in utero fracture in a mare with dystocia has not been reported. A 7-year-old multiparous Standardbred mare presented to a referral center for correction of dystocia. Assisted vaginal delivery and controlled vaginal delivery attempts were unsuccessful mainly because of contracted tendons impeding mutation. As the foal was alive, a cesarean section was elected. The foal was delivered but ultimately euthanized because of the congenital abnormalities. Computed tomography of the right forelimb of the foal along with gross examination and histologic evaluation of the right metacarpus revealed the malunion of a previous in utero fracture. While a few cases have been reported of in utero fracture, many of these were in abortuses and not in fetuses at term, making this case a new presentation and potential etiology for dystocia., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Two goats (6 months old and 5 years old) were evaluated for neurological signs including laboured breathing, stiffness and obtundation. Solitary masses were noted in the brainstem and spinal cord, respectively. Histopathology of both cases revealed the lesions were composed of a mixture of glial and neuronal cells, consistent with glioneuronal hamartomas. The cause of death was attributed to the mass in the 6-month-old, while the cause of death in the 5-year-old was attributed to listeriosis. Hamartomas of neural origin are rarely described in veterinary species, and this report represents the first report of glioneuronal hamartomas in goats., Competing Interests: Conflict of Interest Statement The authors declare no potential conflicts of interest with respect to the research, authorship or publication of this article., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Cats are important in the epidemiology of Toxoplasma gondii infection because they are the only hosts that can excrete the environmentally resistant oocysts in the environment. Although exposure is common (approximately 30% of cats in the USA), clinical toxoplasmosis is relatively rare. Here, we report overwhelming disseminated toxoplasmosis in two litter mate 8-week-old kittens, thought to have acquired toxoplasmosis postnatally. Five domestic shorthair kittens, approximately 2-3 weeks of age, and the queen were found in upstate New York by a rescue group in spring of 2018. The kittens and queen were placed in a foster home for approximately 4-5 weeks and then transferred to a shelter. Two kittens died unexpectedly following a short illness. Postmortem examination of the two deceased kittens revealed overwhelming toxoplasmosis and the presence of entero-epithelial stages in small intestine, suggestive of recent ingestion of infected tissues. Antibodies to T. gondii were found in the deceased kittens and the queen but not in the three asymptomatic littermate kittens. No obvious cause of immunosuppression was demonstrated. Genetic typing of T. gondii from DNA extracted from liver and lungs of both kittens revealed Toxo DB #4 genotype, commonly found in wildlife. Owners and veterinarians should be aware of dangers of feeding raw meat to cats and contact with infected cat feces. Procedures to safely handle T. gondii infected feces in hospital setting are outlined., (Copyright © 2019. Published by Elsevier B.V.)

Objective: Thermal radiofrequency (TRF) of the saphenous nerve (a sensory nerve) combined with pulsed radiofrequency (PRF) of the sciatic nerve (a sensory and motor nerve) might relieve intractable stifle osteoarthritis (OA) pain in dogs. The objective was to determine if saphenous nerve TRF induces Wallerian degeneration and if sciatic nerve PRF induces degeneration or dysfunction., Study Design: Blinded, controlled, randomized, preclinical study., Animals: A group of six intact, female Beagle dogs aged 14-16 months., Methods: In each dog, one pelvic limb was assigned randomly to the control group and the other to the treatment group. Dogs were anesthetized and, using ultrasonography, radiofrequency electrodes were positioned adjacent to saphenous and sciatic nerves bilaterally; TRF and PRF were performed only in the treatment limb. Motor nerve conduction velocity (MNCV) was measured in both sciatic nerves 2 weeks later, and the dogs were euthanized. Hematoxylin and eosin-stained sections of saphenous and sciatic nerves were examined using light microscopy. Degeneration and inflammation were scored 0 (none) to 3 (severe). A one-tailed, paired Wilcoxon signed-rank test was used to test for differences in scores and MNCV between control and treatment nerves., Results: Degeneration and inflammation scores were higher in treatment saphenous nerves in 5/6 dogs [83%; 95% confidence interval (CI), 36%, 99%]; however, after Bonferroni correction only degeneration score was higher (p = 0.0313). Degeneration, inflammation or decreased MNCV were not observed in sciatic nerves (each outcome: 0/6 nerves, 0%; 95% CI, 0%, 48%). No dogs experienced postprocedural pain or neurological deficits., Conclusions and Clinical Relevance: The degeneration in TRF-treated saphenous nerves appears sufficient to impair transmission. Sciatic nerve PRF did not cause degeneration with attendant motor deficits, consistent with a proposed neuromodulatory mechanism. A clinical trial is needed to confirm the combined techniques produce analgesia without motor deficits in dogs with stifle OA., (Copyright © 2019 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.)

Introduction: Children with high body mass index (BMI) values have been demonstrated to have precocious dental development. Research has largely focused on cross-sectional data sets, leaving an incomplete understanding of the longitudinal relationship between BMI and dental maturation., Methods: We used a pure longitudinal growth series to examine the relationship between dental development and childhood BMI. Periapical radiographs from 77 children from the Iowa Growth Study were used to estimate dental development for those with high BMI values., Results: We confirmed prior studies in finding that children with higher BMI values were more likely to have advanced dental development for their ages (P <0.001). BMI at age 4 years was predictive for the timing of dental development at age 12 (P = 0.052). The precocity of the rate of dental development accelerated across growth. Overall dental development scores also correlated with the age of dental eruption for the mandibular canines and first premolars (P <0.001)., Conclusions: High BMI values at young ages predict advanced dental development at later times, suggesting a long-term effect of BMI on dental maturation and implying the need for earlier orthodontic interventions in obese children. These results corroborate those of previous studies, building further evidence that relatively early dental eruption is another consequence of childhood obesity., (Copyright © 2018 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)

A 9-month-old, female, domestic longhair cat with severe anaemia tested positive for feline leukaemia virus (FeLV) and was humanely destroyed and submitted for necropsy examination. Gross findings included a non-divided rostral telencephalon, consistent with semilobar holoprosencephaly. Histological examination of the bone marrow revealed an almost complete absence of erythroid precursor cells, consistent with pure red cell aplasia, and mild to moderate myelofibrosis. This case demonstrates a very unusual central nervous system defect, as well as an atypical presentation of pure red cell aplasia, in a FeLV-positive kitten., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Essential thrombocythemia (ET) and polycythemia vera (PV) are myeloproliferative neoplasms (MPNs) that share the JAK2(V617F) mutation in hematopoietic stem cells, leading to excessive production of predominantly platelets in ET, and predominantly red blood cells (RBCs) in PV. The major cause of morbidity and mortality in PV and ET is thrombosis, including cerebrovascular occlusive disease., Objectives: To identify the effect of excessive blood cells on cerebral microcirculation in ET and PV., Methods: We used two-photon excited fluorescence microscopy to examine cerebral blood flow in transgenic mouse models that mimic MPNs., Results and Conclusions: We found that flow was 'stalled' in an elevated fraction of brain capillaries in ET (18%), PV (27%), mixed MPN (14%) and secondary (non-MPN) erythrocytosis (27%) mice, as compared with controls (3%). The fraction of capillaries with stalled flow increased when the hematocrit value exceeded 55% in PV mice, and the majority of stalled vessels contained only stationary RBCs. In contrast, the majority of stalls in ET mice were caused by platelet aggregates. Stalls had a median persistence time of 0.5 and 1 h in ET and PV mice, respectively. Our findings shed new light on potential mechanisms of neurological problems in patients with MPNs., (© 2014 International Society on Thrombosis and Haemostasis.)

Distal-less 3 (Dlx3)(-/-) mice die at E9.5 presumably due to an abnormal placental phenotype including reduced placental vasculature and secretion of placental growth factor. To examine the role of Dlx3 specifically within the epiblast, Dlx3 conditional knockout mice were generated using an epiblast-specific Meox2(CreSor) allele. Dlx3(-/fl), Meox2(CreSor) animals were born at expected frequencies and survived to weaning providing indirect evidence that loss of Dlx3 within the trophoectoderm plays a critical role in fetal survival in the Dlx3(-/-) mouse. We next examined the hypothesis that loss of a single Dlx3 allele would have a negative impact on placental and fetal fitness. Dlx3(+/-) mice displayed reduced fetal growth beginning at E12.5 compared with Dlx3(+/+) controls. Altered fetal growth trajectory occurred coincident with elevated oxidative stress and apoptosis within Dlx3(+/-) placentas. Oral supplementation with the superoxide dismutase mimetic, Tempol, rescued the fetal growth and placental cell death phenotypes in Dlx3(+/-) mice. To determine the potential mechanisms associated with elevated oxidative stress on the Dlx3(+/-) placentas, we next examined vascular characteristics within the feto-placental unit. Studies revealed reduced maternal spiral artery luminal area in the Dlx3(+/-) mice receiving water; Dlx3(+/-) mice receiving Tempol displayed maternal spiral artery luminal area similar to control Dlx3(+/+) mice. We conclude that reduced Dlx3 gene dose results in diminished fetal fitness associated with elevated placental cell oxidative stress and apoptosis coincident with altered vascular remodeling. Administration of antioxidant therapy ameliorated this feto-placental phenotype, suggesting that Dlx3 may be required for adaptation to oxidative stresses within the intrauterine environment., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

During maxillary permanent canine eruption, the deciduous canine root is selectively resorbed while the adjacent permanent lateral incisor root is left intact. An understanding of this selective resorption could provide insights into the cause of moderate to severe iatrogenic root resorption during orthodontic tooth movement. This study investigated the possible role of extracellular matrix (ECM) proteins in the selective resorption process. The spatial expression patterns of 2 ECM proteins, osteopontin (OPN) and bone sialoprotein (BSP), were assessed within the periodontal ligament (PDL) surrounding root surface areas of deciduous and permanent teeth. Intact and resorbed root surface areas from 14 deciduous roots and intact root surface areas from 12 permanent tooth roots were examined. In the deciduous roots, BSP and OPN were locally expressed in the cell layer adjacent to the root surface and most intensely concentrated in areas surrounding and within odontoclasts proximal to the resorptive lacunae. In contrast, BSP and OPN were expressed in a generalized pattern throughout the PDL of permanent roots. These preliminary findings suggest a differential expression of ECM proteins on deciduous versus permanent tooth roots, which could act as a signal for selective odontoclast adhesion to, and subsequent resorption of, deciduous root surfaces.

When a permanent maxillary canine erupts apical to the permanent lateral incisor and the deciduous canine, resorption typically takes place only on the deciduous canine root. An understanding of this differential resorption could provide insight into the reasons for excessive iatrogenic root resorption during orthodontic tooth movement. The purpose of the present study was to examine the response of roots of permanent lateral incisors and deciduous canines to simulated resorption, and to acid and enzyme attack, reflecting the physiologic environment of an erupting permanent canine. Groups of maxillary permanent lateral incisor and deciduous canine roots were exposed to 5 combinations of Ten Cate demineralizing solution, Ten Cate demineralizing solution with EDTA, and a Type I collagenase solution. Sections of the roots were examined under a polarized light microscope. Analysis of variation of the resulting root lesions demonstrated that the lesion depths for deciduous canines were greater than those for permanent lateral incisors when averaged across 4 of the conditions (F(1,24) = 7.49, P =.0115). On average, deciduous canine roots demonstrated lesions 10% deeper than did permanent lateral incisor roots. We concluded that when deciduous canine and permanent lateral incisor roots are subjected to acid and enzyme attack, reflecting the physiologic environment of an erupting permanent canine, significantly deeper demineralized lesions are seen in the deciduous roots compared with the permanent roots. This finding may partially explain the differential root resorption during permanent tooth eruption.

Objectives: Our goal was to determine whether the radiographic fractal dimension of the maxillary and mandibular alveolar processes is related to bone density of the alveolar processes, spine, hip, and radius in healthy women., Study Design: Thirty-seven dentate healthy white women aged 20 to 78 years underwent assessment of systemic and alveolar process bone. After a periodontal examination, D-speed vertical bite-wing and periapical radiographs with aluminum step wedges and a density correction algorithm were used to make alveolar process fractal dimension and density calculations within regions of interest that avoided crestal bone and intrabony defects. Anteroposterior (L1-L4) and lateral (L2-L4) lumbar spine, total hip, and total wrist densities were determined by means of dual energy x-ray absorptiometry., Results: Correlation analysis revealed significant relationships between maxillary alveolar process fractal dimension and maxillary alveolar process density (r = 0.47, P < or =.01), mandibular alveolar process density (r = 0.48, P < or =.01), and mandibular alveolar process fractal dimension (r = 0.44, P < or =.05); and between mandibular alveolar process fractal dimension and maxillary alveolar process density (r = 0.54, P < or =.01) and mandibular alveolar process density (r = 0.58, P < or =.001). No significant relationships were found between the maxillary alveolar process or the mandibular alveolar process fractal dimension and the density of any postcranial regions., Conclusions: In healthy women, the alveolar process radiographic fractal dimension is significantly related to the alveolar process density but is not related to the density of the spine, hip, or radius.

Our purpose was to investigate the impact of mandibular advancement surgery on profile esthetics and to attempt to define guidelines that could be of value to the clinician in predicting profile esthetic change. The sample consisted of 34 patients who had been treated with a combination of orthodontics and mandibular advancement surgery without genioplasty. Initial (pretreatment) and final (posttreatment) cephalometric radiographs of each patient were used to produce silhouette images and to quantify skeletal changes that occurred with surgery. The images were displayed randomly to lay persons and orthodontic residents who were asked to score the esthetics of each profile. On average, after mandibular advancement surgery, B point moved forward 5.0 mm (SD = 2.6 mm) and downward 4.7 mm (SD = 3.1 mm), and the ANB angle decreased 3.0 degrees (SD = 1.6 degrees ) Graphical analysis and results of paired t tests revealed that for patients with an initial ANB angle >/= 6 degrees, a consistent improvement in profile esthetics was seen following surgery (P

Objective: Our goal in this investigation was to examine the mandibular bone density and radiographic textural changes and the relationship between mandibular and spinal bone mineral density in an osteoporotic rabbit model., Study Design: Three adult female New Zealand white rabbits in each of 4 groups received daily injections of cortisone acetate at a dosage of 0.0 (control), 3.0, 7.5, or 15.0 mg/kg for 4 weeks. The rabbits were then killed, and the mandible and spine of each animal were removed. Digital radiographs (70 kVp, 10 mA, 8 impulses) of the hemimandibles and spines were made. Lateral and anteroposterior bone densities of the lumbar spine (L2) were calculated, and average mandibular interdental bone density, fractal dimension, and gradient values were calculated., Results: Correlation analysis revealed that cumulative steroid dose was strongly related to mandibular bone density (r = -0.80, P <.01), moderately related to mandibular fractal dimension (r = -0.61, P <. 05), and moderately related to anteroposterior lumbar spine density (r = -0.64, P <.05). Moderate correlations were found between mandibular interdental bone density and spinal density (r = 0.56, P <.05), but mandibular fractal dimension was not related to spinal density., Conclusions: In osteoporotic female rabbits, mandibular bone mineral density decreases in relation to spinal density and cumulative steroid dose. Mandibular fractal dimension decreases with cumulative steroid dose but is not significantly related to either mandibular density or spinal density.

Objective: The purpose of this study was to determine whether the mandibular alveolar striae patterns seen in radiographs represent trabecular bone., Study Design: Segments of human cadaver mandible were obtained. Two identical radiographs were made of each segment initially, after removal of trabecular bone, after slight smoothing of the endosteal surface, and after aggressive smoothing of the endosteal surface. The radiographs were projected in random pairs for each sample. Six dentists judged whether a difference in the amount of trabecular bone could be detected., Results: Chi-square test analysis revealed no significant difference in the amount of trabecular bone judged initially and after removal of trabecular bone. A significant difference appeared to exist on radiographs made initially and after slight smoothing. A significant difference was judged to exist on radiographs made after slight removal of the endosteal surface and after aggressive removal of the endosteal surface., Conclusions: Mandibular radiographic striae patterns, interpreted as arising from trabecular bone, actually result from bone patterns on the endosteal surface.

Objective: The purposes of this study were to examine the density correction afforded by curve-fitting algorithms and to investigate whether the device we developed significantly improves the reliability of longitudinal alveolar process bone radiographic density measurements., Study Design: Stepwedges were radiographed over a range of impulse settings, and curve-fitting algorithms were fitted to sets of step images on each digitized film. Differences between the actual thicknesses of an alternate set of steps and their corresponding thickness estimates were calculated. Next, clinicians made periapical radiographs from interproximal bony sites on a dry skull using our imaging device. Differences in bone densities between corresponding regions of interest taken 1 week apart were calculated., Results: Analysis of variance and Duncan's Multiple Range test demonstrated that piecewise linear, third-degree polynomial, and fourth-degree polynomial curves provided significantly better estimates of stepwedge thickness than did sigmoid or first degree polynomial-curves (P < .05) and that the differences between repeat bone density measurements made with density correction were significantly less than those made without density correction (P < .05)., Conclusions: Piecewise linear, third-degree polynomial, and fourth-degree polynomial curve-fitting algorithms provided the best densitometric correction. The use of our imaging device increased the reliability of longitudinal bone density measurements.

The purpose of this investigation was to assess the method proposed by Skieller, Björk, and Linde-Hansen in 1984 to predict mandibular growth rotation. Our sample consisted of 40 randomly selected, untreated, adolescent subjects representative of the patient population generally encountered in orthodontic practice. The four independent variables identified in the Skieller study as having the highest predictive value (mandibular inclination, intermolar angle, shape of the lower border of the mandible, and inclination of the symphysis) were identified on initial lateral cephalograms. The proposed regression equations were applied and predicted mandibular rotations obtained. Final lateral cephalograms made 6 years after the initial profile radiographs were superimposed and actual mandibular rotation recorded. The observed and predicted rotations were compared and regression analyses performed to determine the amount of variability in observed values accounted for by the four variables individually and in combination. Only 5.6% of the variability in mandibular growth rotation could be accounted for using the four variables individually. Only 9% of the variability could be accounted for with a combination of the variables. In addition, we performed a Monte Carlo analysis, which mirrored the Skieller analysis but used random numbers instead of actual cephalometric data, to determine if the Skieller results may simply have capitalized on chance. Using the same forward stepwise selection procedure with a rejection level of P >.1, we found after 5000 simulations that a mean of 84% and a median of 94% of mandibular growth rotation variability could be accounted for using meaningless data in the Skieller analysis. This result was comparable to the Skieller value of 86%. In conclusion, information derived from pretreatment lateral cephalograms using the Skieller, Björk, and Linde-Hansen method does not permit clinically useful predictions to be made in a general population relative to the direction of future mandibular growth rotation.

Objectives: The purpose of this study was to compare D-speed film, E-speed film, and the Soredex Digora system with respect to the detection of periradicular pathosis., Study Design: Radiographic images of 100 cadaver jaws were made with E-speed film, D-speed film, and the Soredex Digora. Each set of 100 images was interpreted by four observers, with 30 days separating each of three viewing sessions from the next. The presence or absence of pathologic (inflammatory) periradicular bone resorption was determined by histologic examination of the samples. The observer performance was compared with the true histologic findings and evaluated with receiver operating characteristic and corrected receiver operating characteristic analysis., Results: No statistically significant differences were found in diagnostic performance among the three radiographic techniques. In addition, no imaging technique was a good indicator of pathosis as determined by histologic analysis., Conclusion: Under the conditions of this study, it was determined that D-speed film, E-speed film, and the Soredex Digora were equivalent diagnostic imaging modalities with regard to the detection of pathologic periradicular bone resorption. No technique predictably indicated inflammatory resorption.

Enamel demineralization during active orthodontic treatment remains a significant problem. The purpose of this in vitro study was to evaluate the efficacy of applying a light-cured unfilled resin, a conventional pit and fissure sealant, to the labial surface of teeth with previously placed orthodontic appliances to prevent demineralization. Orthodontic brackets were bonded to 40 extracted human teeth with a commercially available orthodontic adhesive. The exposed labial surfaces of 30 teeth (experimental group) were sealed with a clear, light-cured, unfilled resin. The remaining 10 teeth (control group) were left unsealed. Both groups were placed in a demineralization environment, and then all teeth were sectioned and examined under polarized light microscopy for the presence or absence of enamel demineralization. Every member of the control group exhibited demineralization of the entire exposed labial surface, whereas 80% of the sealed teeth exhibited no demineralization. Small, isolated areas of enamel loss were seen in six of the sealed teeth representing "breaks" in the sealant layer. The results of this study indicate that light-cured sealant treatment after orthodontic appliance placement significantly reduces enamel demineralization.

Objectives: This in vitro study examined radiographic fractal dimension changes in alveolar process bone during simulated osteoporosis., Study Design: Ten specimens of human maxillary alveolar process bone were progressively decalcified, and the percentage of calcium lost at each decalcification stage was quantified. Four radiographs of each specimen, together with an aluminum step-wedge, were exposed at 70 kVp at each stage. The test set of 560 radiographs was digitized, identical bony regions of interest were selected from the density-corrected images of each specimen, the regions were digitally filtered to reduce film-grain noise, and fractal dimension was computed on a line-to-line basis. Correlation analysis quantified the relationship between calcium loss and fractal dimension change. Analysis of variance and Duncan's multiple range test determined whether a difference existed in fractal dimension computed from images at x-ray beam angulations of -5, 0, and +5 degrees., Results: A strong correlation (average r = -0.94, p < or = 0.0037) was found between generalized demineralization and decreasing fractal dimension. In every bone sample fractal dimension changed significantly (p < or = 0.0189) with angular change., Conclusions: Radiographic fractal dimension holds promise for detecting simulated osteoporosis in the maxilla under ideal conditions, but the sensitivity of fractal dimension to small x-ray beam angular change renders its clinical application questionable.

The purpose of this study was to compare the intrusion anchorage potential of teeth to osseointegrated titanium implants. Titanium implants were surgically placed unilaterally in a healed mandibular fourth premolar extraction site in eight adult mongrel dogs. The implants were surgically uncovered 3 months later and second stage abutments with soldered edgewise brackets secured. Edgewise brackets were also placed on the ipsilateral third premolars and on the contralateral third and fourth premolars. Segmental edgewise arch wires were placed between the implant and the third premolar and between the contralateral third and fourth premolars. Intrusion arch wire bends (v-bends) just mesial to the implant and the fourth premolar brackets were adjusted to apply a 50 to 60 gm intrusive force to the third premolars, bilaterally. Seven weeks later this force was increased to approximately 100 gm. Force levels were monitored biweekly for a total period of 16 weeks. Superimposition of initial and final periapical radiographs with bone markers demonstrated that for each dog the implant remained immobile and the third premolar on the implant anchor side was intruded in a curved path. On the contralateral side of the arch the dental anchor (fourth premolar) underwent an adverse reactive tip-back movement, and the third premolar was not intruded. We conclude that rigid endosseous implants are superior to dental anchorage for orthodontic intrusion of teeth and offer a potential means to intrude anterior teeth in adult patients with missing posterior teeth.

Conventional records are often inadequate for planning correction of complex dentofacial deformities. A treatment planning system, consisting of computed tomographic-generated jaw models mounted on a special articulator, allows for presurgical decisions about the correctness of surgical movements or the need for alternative approaches.

Recent evidence indicates that extracting unerupted mandibular third molars neither decreases interdental force measurably nor prevents mandibular incisor crowding. There are valid reasons for extracting third molars. But extraction for the exclusive purpose of relieving interdental pressure and thereby preventing incisor crowding is unwarranted.

Relapse of aligned mandibular anterior teeth and the progressive collapse of the mandibular arch is a significant problem for orthodontists. However, identification of a specific cause of such relapse has proved elusive. The transseptal fiber system is thought to stabilize teeth against separating forces. It is hypothesized that this fiber system may actually maintain the contacts of approximating teeth in a state of compression, the long-term result of which could be contact slippage and collapse of the arch. The interproximal force (IPF) at the mandibular first molar-second premolar contact was investigated on the basis of previous studies with this representative contact. The IPF was measured in 10 subjects at six different widths of contact separation. By means of graphic plotting techniques, the IPF at zero separation was calculated to estimate the contact force when the molar and premolar were actually touching. The mean IPF at zero separation was found to be 36.7g (SE = 6.6g), and a t test confirmed the hypothesis that a state of compression between contacts exists (p less than 0.0001). After chewing, the mean IPF at zero separation was 57.2g (SE = 9.1g), and a paired t test revealed an increase in contact compression had resulted (p less than 0.01). It was concluded that the periodontium exerts a continuous force on the mandibular dentition and that this force acts to maintain the contacts of approximating teeth in a state of compression. This force is increased after occlusal loading and may help to explain long-term crowding of the mandibular anterior teeth, physiologic drifting of teeth, and maintenance of posterior dental contacts after interproximal wear.

Lack of adolescent patient compliance is a significant problem in orthodontics. The purpose of this study was to examine the feasibility of using a commercially available adolescent personality test to predict the behavior of adolescent patients in an orthodontic practice. Specifically, this study tested (1) the use of the Millon Adolescent Personality Inventory (MAPI) as an appropriate instrument for an adolescent orthodontic population and (2) the correlation between MAPI test results and orthodontic compliance. The MAPI was administered to 104 13- to 18-year-old orthodontic patients who were blindly evaluated for orthodontic compliance after 2 years of treatment. Twenty modified MAPI scales with high internal consistencies (coefficient alpha = 0.66 to 0.87) were developed. Factor analytic results demonstrated that the modified scales had a dimensionality that was similar to that of the original test. Seven of 20 test scales and gender were found to be significantly correlated with orthodontic compliance. These eight variables contribute to a predictive model that accounts for 24% of the variance in assessing orthodontic compliance. We conclude that the MAPI has potential as a useful instrument in assisting the management of adolescent patient behavior in an orthodontic practice.

Erupting mandibular third molars are implicated as a cause of anterior crowding of mandibular teeth. The goal of this two-part investigation was to measure the mesial force exerted by unerupted mandibular third molars. We hypothesized that such a force increases the tightness of all proximal posterior tooth contacts mesial to the mandibular second molar, and that surgical removal of third molars relieves the tightness by eliminating this force. The contact tightness between mandibular posterior teeth was measured bilaterally in 20 patients with bilateral unerupted mandibular third molars, immediately before and after unilateral removal of a third molar. We found unexpectedly that mean proximal tightness decreased bilaterally in all contacts that were measured after unilateral removal of a third molar, and we did not detect a mesial force exerted by unerupted third molars. We suspected that this bilateral relief of contact tightness resulted from placing the patients in a supine position for surgery. The second part of the experiment was conducted to determine the effects of postural change on proximal contact tightness where no surgery had been performed. For ten subjects we discovered a mean decrease in the tightness of all mandibular posterior contacts 2 hours after the patient had been moved from an upright to a supine position. The greatest mean decrease (-32%, p less than 0.0001) was found at the most posterior tooth contact. We conclude that surgical removal of unerupted mandibular third molars does not significantly reduce proximal contact tightness, but that simple movement from an upright to a supine position relieves such tightness dramatically.(ABSTRACT TRUNCATED AT 250 WORDS)

The objective of this study was to determine the relationship between the anterior component of occlusal force and malalignment of the mandibular anterior teeth. The anterior component of occlusal force that resulted from axially loading the second molars was measured in 15 subjects with varying degrees of mandibular anterior dental malalignment. Malalignment of the mandibular anterior teeth was found to be related to the magnitude of the anterior component of occlusal force and to the tightness of interproximal contacts in the mandibular posterior segments.

The purpose of this investigation was to design and develop instrumentation to measure the anterior component of occlusal force generated by a single tooth under a known axial load. An additional objective was to quantify the distribution and dissipation of this force as it progressed anteriorly. The anterior component of the occlusal force generated by the left second molar was calculated from frictional force measurements at each contact mesial to the first molars in both dental arches. The distribution of this force and its dissipation were determined for 15 subjects. When a load was placed on the posterior teeth, the anterior component of the occlusal force was found to progress anteriorly through interproximal contacts and not to progress beyond open contacts. The mean magnitude of this force for a conservative occlusal load of 20 pounds was unexpectedly high: 5 pounds against the premolars and 1 pound against the canines. In some subjects this force crossed the dental midline and continued around the arch to the canine of the contralateral side. The distribution and dissipation of the anterior component of the occlusal force anteriorly approximated an exponential decay function.

An investigation was conducted to clarify the relationship between orthodontic treatment and caries incidence. DMF indices from 308 orthodontically treated and 305 untreated naval recruits were compared. Contrary to expectations, there was no evidence that orthodontic treatment increases caries experience. Orthodontically treated subjects had significantly fewer diseased surfaces--a difference averaging one less diseased surface per patient. Treatment status did not generally affect the number of filled surfaces. Treated subjects had more missing teeth if first premolars were considered, but untreated subjects had more missing teeth if first premolars were not considered. No significant correlation was found between caries incidence and duration of orthodontic treatment. The epidemiologic basis and significance of these findings are discussed.

A computerized record system has been developed which is capable of capturing, storing, and displaying, in a standard clinical format, the information generated during comprehensive general dental examinations. This system has been tested during examination of 200 patients.