Acute physiological responses to a pyramidal exercise protocol and the associations with skin temperature variation in different body areas.

This study aimed to examine the skin temperature (Tsk) variations in five regions of interest (ROI) to assess whether possible disparities between the ROI's Tsk could be associated with specific acute physiological responses during cycling. Seventeen participants performed a pyramidal load protocol on a cycling ergometer. We synchronously measured Tsk in five ROI with three infrared cameras. We assessed internal load, sweat rate, and core temperature. Reported perceived exertion and calves' Tsk showed the highest correlation (r = -0.588; p < 0.01). Mixed regression models revealed that the heart rate and reported perceived exertion were inversely related to calves' Tsk. The exercise duration was directly associated with the nose tip and calf Tsk but inversely related to the forehead and forearm Tsk. The sweat rate was directly related to forehead and forearm Tsk. The association of Tsk with thermoregulatory or exercise load parameters depends on the ROI. The parallel observation of the face and calf Tsk could indicate simultaneously the observation of acute thermoregulatory needs and individual internal load. The separate Tsk analyses of individual ROI appear more suitable to examine specific physiological response than a mean Tsk of several ROI during cycling.

Application of machine learning algorithms in thermal images for an automatic classification of lumbar sympathetic blocks.

PURPOSE: There are no previous studies developing machine learning algorithms in the classification of lumbar sympathetic blocks (LSBs) performance using infrared thermography data. The objective was to assess the performance of different machine learning algorithms to classify LSBs carried out in patients diagnosed with lower limbs Complex Regional Pain Syndrome as successful or failed based on the evaluation of thermal predictors. METHODS: 66 LSBs previously performed and classified by the medical team were evaluated in 24 patients. 11 regions of interest on each plantar foot were selected within the thermal images acquired in the clinical setting. From every region of interest, different thermal predictors were extracted and analysed in three different moments (minutes 4, 5, and 6) along with the baseline time (just after the injection of a local anaesthetic around the sympathetic ganglia). Among them, the thermal variation of the ipsilateral foot and the thermal asymmetry variation between feet at each minute assessed and the starting time for each region of interest, were fed into 4 different machine learning classifiers: an Artificial Neuronal Network, K-Nearest Neighbours, Random Forest, and a Support Vector Machine. RESULTS: All classifiers presented an accuracy and specificity higher than 70%, sensitivity higher than 67%, and AUC higher than 0.73, and the Artificial Neuronal Network classifier performed the best with a maximum accuracy of 88%, sensitivity of 100%, specificity of 84% and AUC of 0.92, using 3 predictors. CONCLUSION: These results suggest thermal data retrieved from plantar feet combined with a machine learning-based methodology can be an effective tool to automatically classify LSBs performance.

Chronic and Acute Effects on Skin Temperature from a Sport Consisting of Repetitive Impacts from Hitting a Ball with the Hands.

Valencian handball consists in hitting the ball with the hands and it may contribute to injury development on the hands. This study aimed to analyze skin temperature asymmetries and recovery after a cold stress test (CST) in professional players of Valencian handball before and after a competition. Thirteen professional athletes and a control group of ten physically active participants were measured. For both groups, infrared images were taken at the baseline condition; later they underwent a thermal stress test (pressing for 2 min with the palm of the hand on a metal plate) and then recovery images were taken. In athletes, the images were also taken after their competition. Athletes at baseline condition presented lower temperatures (p < 0.05) in the dominant hand compared with the non-dominant hand. There were asymmetries in all regions after their match (p < 0.05). After CST, a higher recovery rate was found after the game. The regions with the most significant differences in variation, asymmetries and recovery patterns were the index, middle and ring fingers, and the palm of the dominant hand. Taking into account that lower temperatures and the absence of temperature variation may be the consequence of a vascular adaptation, thermography could be used as a method to prevent injuries in athletes from Valencian handball.

Skin temperature measurement in individuals with spinal cord injury during and after exercise: Systematic review.

BACKGROUND: Athletes with spinal cord injury (SCI) have difficulties in maintaining thermal homeostasis during exercise due to their lower sweat capacity and skin vasodilation. Skin temperature (Tsk) assessment, as opposed to core temperature, has become more widely accepted due to its non-invasive nature. The aims of this systematic review was to collate research studies that measured Tsk of individuals with SCI during or after exercise, study their Tsk response, taking into account the method employed, the environmental and exercise conditions, and to identify the different cooling strategies and their effect during exercise. METHODS: Pubmed, Web of Science and Scopus databases were searched to identify the articles published since year 2000. Two reviewers working independently extracted data and assessed the quality of the articles included. If they disagreed, a third reviewer was consulted. ROBINS-I scale was used to assess the quality of the articles, and the review has been conducted in agreement with PRISMA guidelines. RESULTS: Twenty studies were included in this review. 84% of them presented moderate, serious or critical risk of bias. The entire of the studies assessed Tsk during exercise, but only seven studies measured it during rest or after exercise. Eighteen studies used contact thermometry to assess Tsk and the two remaining studies employed non-contact techniques. Seven studies were conducted in warm conditions (>31.5°C) and the remaining studies in moderate conditions (10°C to 26.6°C). According to cooling strategies, ice vests and water spray are effective in reducing Tsk and decreasing the risk of heat stroke. CONCLUSIONS: The 90% of the studies applied contact thermometry and due to their effect in the data assessed, it is necessary more research into the SCI population using infrared thermography due to its differences in characteristics, methodology, and applications. The methodological differences among studies make difficult to perform a meta-analysis.

Effect of 10 km run on lower limb skin temperature and thermal response after a cold-stress test over the following 24 h.

Skin temperature assessment has received much attention as a possible measurement of physiological response against stress produced by exercise and research studies usually measure skin temperature 24 or 48 h after exercise. Scientific evidence about skin temperature evolution during the 24-h period immediately after exercising is, however, scarce. The aim was to assess the effect of a 10 km run at moderate intensity on baseline skin temperature and thermal response after a cold stress test during that 24 h period. Fourteen participants were measured before, immediately after, and at 2, 5, 9 and 24 h after a 10 km run at a perceived exertion rate of 11 points (max 20 points). Fourteen control participants who undertook no exercise were also measured during that day. The measurements included muscle pain and fatigue perception, reactive oxygen species, heart rate variability, skin temperature of the lower limbs, and skin temperature after cold stress test. Exercise resulted in a skin temperature increase (e.g., 0.5-1.3 °C of posterior leg 9 h after exercise) and this effect continued in some regions (0.4-0.9 °C of posterior leg) over that 24 h period. However, the thermal response to the cold stress test remained the same (p > 0.05). In conclusion, 10 km aerobic running exercise results in a skin temperature increase, peaking at between 5 and 9 h after exercise, but does not alter the thermal response to a cold stress test. This study provides a sound basis for post-exercise skin temperature response that can be used as a setting-off point for comparisons with future studies that analyze greater muscle damage.

Plantar pressure distribution during running with a self-customized foot orthosis in a home microwave.

The individualization of a custom-made foot orthosis could provide improvements in plantar loading distribution regarding a prefabricated one. However, not all runners can afford it because of its high cost. A new type of low-cost prefabricated foot orthoses with self-customization could be the solution. The aim of the study was to evaluate if self-customized prefabricated foot orthoses (SCFO) could improve plantar pressure distribution with respect to generic prefabricated ones without customization, during the intense prolonged running. Thirty healthy recreational runners performed two tests of 30 min running on a treadmill, each one with a foot orthosis condition, on different days. Mean peak pressure, pressure-time integral, relative pressure and stance time were measured at the beginning and at the end of the tests. Plantar pressure data were analyzed in nine foot regions. Two-way repeated-measures ANOVAs were performed. SCFO reduced relative pressure in metatarsals (P < 0.005) and lateral heel (P = 0.004), thanks to a greater involvement of arch area in mean peak pressure (medial: P = 0.006 and lateral: P = 0.019) and relative pressure (P < 0.001). In general, prolonged run increased pressures in forefoot, in both foot orthosis, but with lower values in metatarsals with SCFO (P < 0.022), which also helped reduce relative pressure in midfoot (P = 0.007) and medial heel (P = 0.035). Stance time was not modified in any case (P > 0.05). In conclusion, customization and better fit of a low-cost prefabricated foot orthosis can improve plantar pressure distribution during a prolonged run, being a good prevention mechanism for plantar overloading in healthy runners.

Reproducibility of Skin Temperature Response after Cold Stress Test Using the Game Ready System: Preliminary Study.

The objective of this preliminary study was to determine the reproducibility of lower limbs skin temperature after cold stress test using the Game Ready system. Skin temperature of fourteen participants was measured before and after cold stress test using the Game Ready system and it was repeated the protocol in four times: at 9:00, at 11:00, at 19:00, and at 9:00 h of the posterior day. To assess skin temperature recovery after cold stress test, a logarithmic equation for each region was calculated, and constant (ß0) and slope (ß1) coefficients were obtained. Intraclass correlation coefficient (ICC), standard error (SE), and within-subject coefficient of variation (CV) were determined. No differences were observed between measurement times in any of the regions for the logarithmic coefficients (p > 0.38). Anterior thigh (ß0 ICC 0.33-0.47; ß1 ICC 0.31-0.43) and posterior knee (ß0 ICC 0.42-0.58; ß1 ICC 0.28-0.57) were the regions with the lower ICCs, and the other regions presented values with a fair and good reproducibility (ICC > 0.41). Posterior leg was the region with the better reproducibility (ß0 ICC 0.68-0.78; ß1 ICC 0.59-0.74; SE 3-4%; within-subject CV 7-12%). In conclusion, cold stress test using Game Ready system showed a fair and good reproducibility, especially when the posterior leg was the region assessed.

Quantitative Analysis of Real-Time Infrared Thermography for the Assessment of Lumbar Sympathetic Blocks: A Preliminary Study.

Lumbar sympathetic blocks (LSBs) are commonly performed to treat pain ailments in the lower limbs. LSBs involve injecting local anesthetic around the nerves. The injection is guided by fluoroscopy which is sometimes considered to be insufficiently accurate. The main aim was to analyze the plantar foot skin temperature data acquired while performing LSBs in patients with complex regional pain syndrome (CRPS) affecting the lower limbs. Forty-four LSBs for treating lower limb CRPS in 13 patients were assessed. Pain medicine physicians visualized the infrared thermography (IRT) video in real time and classified the performance depending on the observed thermal changes within the first 4 min. Thirty-two percent of the cases did not register temperature variations after lidocaine was injected, requiring the needle to be relocated. Differences between moments are indicated using the 95% confidence intervals of the differences (CI 95%), the Cohen effect size (ES) and the significance (p value). In successful cases, after injecting lidocaine, increases at minute 7 for the mean (CI 95% (1.4, 2.1 °C), p < 0.001 and ES = 0.5), at minute 5 for maximum temperature (CI 95% (2.3, 3.3 °C), p < 0.001 and ES = 0.6) and at minute 6 for SD (CI 95% (0.2, 0.3 °C), p < 0.001 and ES = 0.5) were observed. The results of our preliminary study showed that the measurement of skin temperature in real time by infrared thermography is valuable for assessing the success of lumbar sympathetic blocks.

Impact accelerations during a prolonged run using a microwavable self-customised foot orthosis.

The use of custom-made foot orthoses has been associated with numerous benefits, such as decreased impact accelerations. However, it is not known whether this effect could be due to better customisation. The present study analysed the effects of the first generation of  a microwavable prefabricated self-customised foot orthosis vs. a prefabricated standard one on impact accelerations throughout a prolonged run. Thirty runners performed two tests of 30-min running on a treadmill, each one with an orthosis condition. Impact acceleration variables of tibia and head were recorded every 5 min. Microwavable self-customised foot orthosis increased the following variables in the first instants compared to the prefabricated standard one: tibial peak (min1: 6.5 (1.8) vs. 6.0 (1.7) g, P = .009, min5: 6.6 (1.7) vs. 6.2 (1.7) g, P = .035), tibial magnitude (min1: 8.3 (2.6) vs. 7.7 (2.4) g, P = .030, min5: 8.5 (2.6) vs. 7.9 (2.5) g, P = .026) and shock attenuation (min1: 61.4 (16.8) vs. 56.3 (16.3)%, P = .014, min5: 62.0 (15.5) vs. 57.2 (15.3)%, P = .040), and tibial rate throughout the entire run (504.3 (229.7) vs. 422.7 (212.9) g/s, P = .006). However, it was more stable throughout 30-min running (P < .05). These results show that the shape customisation entailed by the thermoformable material does not provide impact acceleration improvements.

Footwear outsole temperature may be more related to plantar pressure during a prolonged run than foot temperature.

Objective. The temperature of the sole of the foot has been suggested as an alternative to the measurement of plantar pressure during running despite the scarce evidence about their relationship. The temperature of the footwear outsole could also be representative of plantar pressure distribution due to its less multifactorial dependence. The aim of the study was to determine if plantar pressure during a prolonged run could be related to plantar temperature, either of the sole of the foot or the footwear outsole.Approach. Thirty recreational runners (15 males and 15 females) performed a 30 min running test on a treadmill. Thermographic images of the sole of the foot and the footwear outsole were taken before and immediately after the test, and dynamic plantar pressure was measured at the end of the test. Pearson correlations and stepwise multiple linear regressions were performed.Main results.Plantar pressure percentage was related to a moderate correlation with plantar temperature percentage in forefoot and rearfoot (P < 0.05), showing a greater relationship with the footwear outsole than with the sole of the foot (r = 0.52-0.73 versusr = 0.40-0.61, respectively). Moreover, moderate correlations were also observed between footwear outsole and sole of the foot temperature variables, especially in rearfoot.Significance. Footwear outsole temperature may be better related to plantar pressure distribution than sole of the foot temperature, in the forefoot and rearfoot. The midfoot is the most sensitive and variable region to analyze, as it does not seem to have any relationship with plantar pressure.

Effect of a Marathon on Skin Temperature Response After a Cold-Stress Test and Its Relationship With Perceptive, Performance, and Oxidative-Stress Biomarkers.

CONTEXT: Although skin-temperature assessment has received much attention in recent years as a possible internal-load measurement, scientific evidence is scarce. PURPOSE: To analyze baseline skin temperature and its rewarming through means of a cold-stress test before and after performing a marathon and to study the association between skin temperature and internal/external-load measurements. METHODS: A total of 16 runners were measured 48 and 24 h before and 24 and 48 h after completing a marathon. The measurements on each day of testing included urine biomarkers of oxidative stress, pain and fatigue perception, skin temperature (at baseline and after a cold-stress test), and jump performance. RESULTS: Reduced jump performance (P < .01 and effect size [ES] = 0.5) and higher fatigue and pain perception were observed 24 h after the marathon (P < .01 and ES > 0.8). Although no differences in baseline skin temperature were observed between the 4 measuring days, posterior legs presented lower constant (P < .01 and ES = 1.4) and higher slope (P = .04 and ES = 1.1) parameters in the algorithmic equations fitted for skin-temperature recovery after the cold-stress test 24 h after the marathon than on the day before the marathon. Regressions showed that skin-temperature parameters could be predicted by the ratio of ortho-tyrosine isomer to phenylalanine (oxidative stress biomarker) and body fat composition, among others. CONCLUSIONS: Although baseline skin temperature was not altered 24 or 48 h after a marathon, the application of cold stress after the marathon would appear to be a good method for providing information on vasoconstriction and a runner's state of stress.

Association between physiological stress and skin temperature response after a half marathon.

OBJECTIVE: The objective of this study was to determine the association between skin temperature response and the physiological stress after a half marathon. APPROACH: Seventeen runners were measured 48 h before, 24 h before, 24 h after and 48 h after completing a half marathon. The measurements on each day of testing included blood markers (creatine kinase [CK] and glutamate oxaloacetate transaminase [GOT]), perception of pain and fatigue (using a visual analogue scale), skin temperature (using infrared thermography), and jump performance (using countermovement jump test). MAIN RESULTS: CK (p  < 0.001 and ES = 2.1), GOT (p  = 0.04 and ES = 1.3), and perception of fatigue and pain (p  < 0.001 and ES > 1.0) increased 24 h after the half marathon, whereas jump performance decreased (p  < 0.01 and ES = 0.4). No increase of skin temperature was observed in the tests after the competition and no regression model was able to predict physiological stress using skin temperature. Only a bivariate correlation was observed between the 24 h variation (pre-24 h) of CK and the skin temperature of the posterior upper limb (p  = 0.04 and r = 0.5), and between the 48 h variation (pre-48 h) of pain perceived and the skin temperature of the knee (p  < 0.01 and r = 0.6). SIGNIFICANCE: In conclusion, follow-up on basal skin temperatures does not seem to be an adequate method to detect physiological stress after a half marathon. In line with the observed results, we recommend caution when interpreting peaks in basal skin temperature in field sports assessments.

Correlation between Topographic Parameters Obtained by Back Surface Topography Based on Structured Light and Radiographic Variables in the Assessment of Back Morphology in Young Patients with Idiopathic Scoliosis.

STUDY DESIGN: Optical cross-sectional study. PURPOSE: To study the correlation between asymmetry of the back (measured by means of surface topography) and deformity of the spine (quantified by the Cobb angle). OVERVIEW OF LITERATURE: The Cobb angle is considered the gold standard in diagnosis and follow-up of scoliosis but does not correctly characterize the three-dimensional deformity of scoliosis. Furthermore, the exposure to ionizing radiation may cause harmful effects particularly during the growth stage, including breast cancer and other tumors. METHODS: Patients aged 13.15±1.96 years (range, 7-17 years; n=88) with Cobb angle greater than 10° were evaluated with X-rays and our back surface topography method through three variables: axial plane (DHOPI), coronal plane (POTSI), and profile plane (PC). Pearson's correlation was applied to determine the correlation between topographic and radiographic variables. One-way analysis of variance and Bonferroni correction were used to compare groups with different grades of scoliosis. Significance was set at p<0.01 and, in some cases, at p<0.05. RESULTS: We detected a positive, statistically significant correlation between Cobb angle with DHOPI (r=0.810) and POTSI (r=0.629) and between PC variables with thoracic kyphosis angle (r=0.453) and lordosis lumbar angle (r=0.275). In addition, we found statistically significant differences for DHOPI and POTSI variables according to the grade of scoliosis. CONCLUSIONS: Although the back surface topography method cannot substitute for radiographs in the diagnosis of scoliosis, correlations between radiographic and topographic parameters suggest that it offers additional quantitative data that may complement radiologic study.

Clinical application of back surface topography by means of structured light in the screening of idiopathic scoliosis.

We present the results of the clinical validity in the screening of idiopathic scoliosis with a nonharming method of back surface topography by means of structured light projection. A total of 155 patients were evaluated (mean age 13.3 years). They were divided into two groups: pathologic patients (scoliosis) and nonpathologic patients (control and asymmetries). An analytical case-control study was carried out. Our topographic method obtained 92% sensitivity and 74% specificity as a screening test in identifying patients with scoliosis (P=0.05). We could quantify the vertebral deformity of scoliosis in the three spatial planes by means of three topographic variables, Horizontal Plane Deformity Index, Posterior Trunk Symmetry Index and Columnar Profile, and to elaborate a combined screening algorithm with good reliability parameters.

Effect of bike-fit in the perception of comfort, fatigue and pain.

The aim of this study was to assess the influence of different bike positions on the perception of fatigue, pain and comfort. Twenty cyclists underwent three tests that involved cycling for 45 min at their individual 50% peak aerobic power output while adopting different positions on the bike. Participants performed the cycling tests adopting three positions defined by two parameters (knee flexion angle [20°, 30°, 40°] and trunk flexion angle [35°, 45°, 55°]) in random order. Angles were measured using a 2D motion analysis system during cycling and applying Fonda's correction factor. Perceptions of comfort, fatigue and pain were reported before the end of each test. The combination of 40° knee flexion and 35° trunk flexion was perceived as the most uncomfortable position. Moreover, greater knee flexion had a negative effect on trunk comfort, accompanied by greater levels of fatigue and pain perception in the anterior part of the thigh and knee. In conclusion, cyclists perceived the most comfortable position to be when the saddle height was within the recommended knee angle (30° calculated from the offset position or 40 ± 4.0° of absolute value). Upright trunk was found to be the most comfortable position for recreational cyclists, where aerodynamics is not so important. Cyclists' bike perceptions should be taken into account when it comes to choosing the most beneficial position, since this can play a role in injury prevention and enhance cycling performance.

Effect of saddle height on skin temperature measured in different days of cycling.

Infrared thermography can be useful to explore the effects of exercise on neuromuscular function. During cycling, it could be used to investigate the effects of saddle height on thermoregulation. The aim of this study was to examine whether different cycling postures, elicited by different knee flexion angles, could influence skin temperature. Furthermore, we also determined whether the reproducibility of thermal measurements in response to cycling differed in the body regions affected or not affected by saddle height. Sixteen cyclists participated in three tests of 45 min of cycling at their individual 50 % peak power output. Each test was performed in a different knee flexion position on the bicycle (20°, 30°, 40° knee flexion when the pedal crank was at 180°). Different knee angles were obtained by changing saddle height. Skin temperatures were determined by infrared thermography before, immediately after and 10 min after the cycling test, in 16 different regions of interest (ROI) in the trunk and lower limbs. Changes in saddle height did not result in changes in skin temperature in the ROI. However, lower knee flexion elicited higher temperature in popliteus after cycling than higher flexion (p = 0.008 and ES = 0.8), and higher knee flexion elicited lower temperature variation in the tibialis anterior than intermediate knee flexion (p = 0.004 and ES = 0.8). Absolute temperatures obtained good and very good intraday reproducibility in the different measurements (ICCs between 0.44 and 0.85), but temperature variations showed lower reproducibility (ICCs between 0.11 and 0.74). Different postures assumed by the cyclist due to different saddle height did not influence temperature measurements. Skin temperature can be measured on different days with good repeatability, but temperature variations can be more sensitive to the effects of an intervention.

Relationship between skin temperature and muscle activation during incremental cycle exercise.

While different studies showed that better fitness level adds to the efficiency of the thermoregulatory system, the relationship between muscular effort and skin temperature is still unknown. Therefore, the present study assessed the relationship between neuromuscular activation and skin temperature during cycle exercise. Ten physically active participants performed an incremental workload cycling test to exhaustion while neuromuscular activations were recorded (via surface electromyography - EMG) from rectus femoris, vastus lateralis, biceps femoris and gastrocnemius medialis. Thermographic images were recorded before, immediately after and 10 min after finishing the cycling test, at four body regions of interest corresponding to the muscles where neuromuscular activations were monitored. Frequency band analysis was conducted to assess spectral properties of EMG signals in order to infer on priority in recruitment of motor units. Significant inverse relationship between changes in skin temperature and changes in overall neuromuscular activation for vastus lateralis was observed (r<-0.5 and p<0.04). Significant positive relationship was observed between skin temperature and low frequency components of neuromuscular activation from vastus lateralis (r>0.7 and p<0.01). Participants with larger overall activation and reduced low frequency component for vastus lateralis activation presented a better adaptive response of their thermoregulatory system by showing fewer changes in skin temperature after incremental cycling test.

Evolución de las características de las arcadas dentarias en dos grupos de edad / Evolution of dental arches characteristics in two age groups

Introducción: Se comparan las características dimensionales de las arcadas dentarias entredos grupos de edades diferentes, adolescentes y adultos jóvenes, para analizar las variaciones asociadasa la edad, sexo y a la influencia del tratamiento ortodóncico. Material y método: Se utilizaron dosmuestras: 88 pares de modelos de escayola de adolescentes (edad media 14,05 años) y 65 de adultos(edad media 22,15 años). Se usó un método digital para la medición de los diámetros mesiodistales delos dientes, distancias intercaninas e intermolares, longitudes de las arcadas y se obtuvo el apiñamientodentario inferior. Para el análisis estadístico se agruparon las muestras de cada grupo de edad porsexos y por tratados/no tratados con ortodoncia. Resultados: Los diámetros mesiodistales de los chicoseran mayores a los de las chicas y los de los adolescentes mayores que los de los adultos, sobretodo en el sexo femenino. La distancia intercanina disminuyó con la edad en las chicas y la intermolarsuperior disminuyó en las chicas no tratadas, mientras que la inferior aumenta en los chicos. Ambaslongitudes de arcada tienden a disminuir en ambos sexos y sobre todo en los grupos de no tratados.Existó un aumento del apiñamiento inferior con la edad en ambos sexos en los individuos tratados.Conclusiones: La pérdida de material dentario con el paso de los años unido a una mayor pérdida delongitud de la arcada podría ser otro factor en el apiñamiento terciario. A su vez, el desplazamientodentario a mesial podría explicar la disminución de los diámetros transversales de caninos y molares,al ocupar una zona más estrecha del arco dentario

Introduction: Dimensional characteristics of dental arches between two groups of age, adolescentsand adults, are compared to analyze the variations associated with age, sex and influence oforthodontic treatment. Material and methods: Two samples of 88 pairs of stone models from adolescents(average age, 14.05 years) and 65 from adults (average age, 22.15 years) were selected. Aftercast scanning, a digital program was used to measure dental mesiodistal diameters, intercanine andintermolar widths, arch lengths and lower dental crowding. For the statistic analysis the samples ofeach age group were divided by sex and by the fact of having been treated or not with orthodontics.Results: The values of the mesiodistal diameters in males were greater than in females, and greater inadolescents than in adults, especially in females. The intercanine distance decreased with age in femalesand the maxillary intermolar distance decreased in untreated females, while the mandibular oneincreased in males. Both arch lengths decreased in both sexes, mainly in the untreated individuals. Thereis an increase of the anteroinferior dental crowding with age in both sexes in the treated group.Conclusions: The loss of dental material with age associated to a greater decrease of arch length couldbe another factor in the later crowding. Also the mesial displacement of the teeth to a narrower partof the arch could explain the decrease in the intercanine and intermolar widths