Orthodontic treatment in an elderly patient with extraction of upper premolar

In the past few years, life expectancy of the world's population has gradually increased and as a result the number of elderly patients seeking orthodontic treatment is becoming higher. The objective of this work is to report a clinical case of orthodontic treatment of an elderly patient in which a dental extraction was performed to correct the relationship between upper and lower arches. The results favoured an improved dental arch relationship and promoted adequate aesthetics and function.     

Individual tooth macrowear pattern guides the reconstruction of Sts 52 (Australopithecus africanus) dental arches

The functional restoration of the occlusal relationship between maxillary and mandibular tooth rows is a major challenge in modern dentistry and maxillofacial surgery. Similar technical challenges are present in paleoanthropology when considering fragmented and deformed mandibular and maxillary fossils. Sts 52, an Australopithecus africanus specimen from Sterkfontein Member 4, represents a typical case where the original shape of the dental arches is no longer preserved. It includes a partial lower face (Sts 52a) and a fragmented mandible (Sts 52b), both incomplete and damaged to such an extent to thwart attempts at matching upper and lower dentitions. We show how the preserved macrowear pattern of the tooth crowns can be used to functionally reconstruct Sts 52's dental arches. High‐resolutiondental stone casts of Sts 52 maxillary and mandibular dentition were mounted and repositioned in a dental articulator. The occlusal relationship between antagonists was restored based on the analysis of the occlusal wear pattern of each preserved tooth, considering all dental contact movements represented in the occlusal compass. The reconstructed dental arches were three‐dimensional surface scanned and their occlusal kinematics tested in a simulation. The outcome of this contribution is the first functional restoration of A. africanus dental arches providing new morphometric data for specimen Sts 52. It is noteworthy that the method described in this case study might be applied to several other fossilspecimens. Am J Phys Anthropol, 2013. © 2013 Wiley Periodicals, Inc.     

Human dental arch shape evaluated by Euclidean-distance matrix analysis

Form differences between biological structures can be evaluated using several approaches. When landmark data are available, a recently proposed method (euclidean-distance matrix analysis) seems to be able to differentiate between size and shape differences. This method also localizes those areas which differ most between the two structures. We have applied it to analyze the sexual dimorphism in dental arch form in a sample of 50 men and 45 women. Subjects ranged in age between 20 and 27 years, and had sound dentitions. Fourteen landmarks, corresponding to the centers of gravity (centroids) of the occlusal surfaces of all permanent teeth (right second molar to left second molar), were individualized on the dental casts of subjects. All the possible linear distances between pairs of teeth were computed, thus creating four mean form matrices (one for each arch within sex). Gender differences were tested by using euclidean-distance matrix analysis. No significant differences were demonstrated in the shape of arches, while male arches proved to be slightly bigger than female arches. © 1993 Wiley-Liss, Inc.     

Heritability of dental arch dimensions in humans.

The purposes of this study were to estimate the heritabilities of several human dental arch dimensions and compare the hereditary differences among kinships and among variables. The sample consisted of 102 Japanese families, each including both parents and one of their offspring, and on average all subjects had relatively well-aligned permanent dentitions. The heritabilities of all variables were estimated from the regression of offspring on parent and on midparent. Results showed that genetics played a role regarding dental arch dimensions, and arch perimeter (sum of tooth width) was a more definite genetic-related factor than other arch dimensions, such as width, length, or size. There were few significant hereditary differences between sons and daughters, and between upper and lower arches for each variable. Sex chromosomal involvement was not confirmed, but maternal effects were found to be more evident in daughters than in sons, for both arches. Comparisons among the heritabilities of overall and of anterior arch dimensions indicated that size of the anterior part of the dental arch might be less resistant to environmental factors, especially in case of the lower arch.     

The British dental arch

Thirty-two dimensions of the maxillary and mandibular dental arches were measured on 320 adult skulls derived from Anglo-saxon to modern times. Multivariate analysis showed varying patterns of contrast between the samples, depending upon which arch dimensions were considered. The results suggest that dental arch changes occur independently of jaw changes.     

儿童下牙弓发育的测量

本研究测量了１９３６名６－１２岁男女儿童的下颌牙弓的宽度和弦长。儿童前牙弓在７－９岁时增长最快,为此时恒尖牙萌出所致,１０岁以后各年龄组均数差异检验没有显著性意义。在整个替牙期,儿童前牙弓宽度约增加２ｍｍ,弦长增加１．８ｍｍ,儿童后牙弓的宽度和弦长约增加１ｍｍ左右。男孩前牙弓宽度比女孩大１ｍｍ左右。后牙弓的宽度和弦箕各年龄组均为男大于女,约１ｍｍ在右。可以把小学年龄阶段儿童的牙列分为乳牙弓、第１恒     

Orthodontic status and head morphology in young males

Complete anthropometrical data on a sample of 111 Russian males aged 20.0+/-2.3 years were obtained to investigate craniofacial morphology according to individual orthodontic status (OS). Subsample analyses were performed, using a variety of grouping factors. a) 1-spacing on both dental arches; 2-absence of crowding, spacing, rotation, or displacement of teeth on both dental arches; 3-crowding on both dental arches; b) 1-spacing on mandible; 2-absence of crowding, spacing, rotation, or displacement of teeth on mandible; 3-crowding on mandible; c) 1-spacing on maxilla; 2-absence of crowding, spacing, rotation, or displacement of teeth on maxilla; 3-crowding on maxilla. Wilks' Lambdas were found to be 0.29 to 0.59; all were significant. CONCLUSIONS: 1. Significant positive and negative correlations were found between craniofacial measurements and an individual's OS. 2. Measurements exhibited statistically significant differences between the groups with different OS at the p<0.05 level and some at p<0.01. 3. Using forward stepwise discriminant analysis, a high difference in craniofacial architecture between the groups with different OS was found. Canonical discriminant analysis indicates the face pattern connected to crowding: relatively high medial vertical mandible height in combination with a vertically long and narrow face; to spacing: a wide face with wide nose and high upper lip is combined with shortened medial vertical mandible height. 4. Depending upon the grouping factor, 10 to 12 variables were chosen in the canonical discriminant model. Classification functions and means of canonical roots were calculated; morphological interpretations of canonical roots were performed. 5. Definitive OS is a complicated product of interaction during the ontogenesis of jaws between the time of teeth eruption and the growth of two growth fields (alveolar and corpus) under the simultaneous influence of hormonal status and the chronological age of the individual.     

The use of metallic implants in the study of facial growth in children: method and application

On the basis of experience gained over a number of years, an account is given of the technique for insertion of the implants, the radiographic method, and the graphic procedure for preparation of growth tracings. Small pins of hard tantalum are hammered into the bone under local analgesia with a pencil-shaped instrument, in the tip of which the implant is placed. No surgical exposure is necessary. Because of remodeling resorption of the bone and eruption of the teeth, the implants can be placed only in certain places in the maxilla and mandible. In implant studies it is necessary to observe a high level of reproducibility in positioning the head in the cephalostat. An X -ray cephalostat with a built-in image intensifier has been designed which enables the position to be monitored by televison. In the graphic procedure, drawings of the arches from dental casts are incorporated in tracings of profile radiographs; the paths of eruption of the teeth and development or the arches can then be examined with the metallic implants as references.     

The influence of age and denture wear on the size of edentulous structures

Objectives : This study was designed to evaluate the influence of age and denture use on the size of arches and residual ridges in edentulous patients. Design : At two nursing homes, maxillary and mandibular stone casts of 302 fully edentulous patients were utilized to measure the size of the arches and residual ridges, according to age and use of complete dentures. Age cohorts were divided into three groups; 60–69, 70–79, and 80–89 years old. Two hundred and forty‐nine denture wearers used complete dentures for at least 2 years before examinations. Fifty‐three non‐denture users had never worn removable prostheses. Chi‐square analysis (p<0.05) was used to establish the possible relations between the linear values and the size indexes of the ridges and arches and the two examined parameters: age and denture wear. Results : Young old patients possessed edentulous structures that were not significantly larger than elderly old patients in both the maxilla and the mandible. Non‐denture users had significantly bigger arches and ridges in both edentulous jaws than denture users. Conclusions : Young old, non‐denture users tended to have bigger residual edentulous tissues compared to elderly old patients who used complete dentures.     

Experimental studies in human tooth wear: I

The construction of a machine called CANIBAL which is capable of simulating the actions of the human mandible during chewing is reported. Powered by an electric motor, a cam activated rocker arm assembly transmits force by means of wires to each point on the mandible where muscles would be attached. A separately adjustable cam, rocker arm, directional pulley and wire represents each muscle. Models of dental arches cast in dental stone or other materials can be mounted and subjected to extended wear. With different cam settings, wear patterns can be produced which resemble those seen on various fossil and living human dental arches.     

Murray James Barrett, dental anthropologist: Yuendumu and beyond

Murray James Barrett (1916-1975) graduated from the University of Adelaide's Bachelor of Dental Surgery programme in 1939 and subsequently became a colleague of Professor Thomas Draper Campbell (1893-1967). Campbell's passion for dental anthropology and his special interest in food habits and dental disease inspired Barrett to commence a longitudinal growth study in the 1960s of Aboriginal Australians living at Yuendumu in the Northern Territory of Australia. This study, referred to as the Dentgro project, involved the collection of dental records, growth data and cultural information about the Wailbri people.Murray Barrett's application of computer technology enabled him to automate the entry of data derived from the Dentgro study and to develop programmes to analyse those data. The collection of dental casts (over 1700 serial casts for more than 450 individuals) and other records have provided a unique resource for research and teaching purposes. The casts have been in constant use for over 40 years providing insights into many aspects of dental development, including: the timing and sequence of tooth emergence; the nature and extent of variation in dental crown size and morphology in human populations; the patterns of growth in the dental arches over time; the range of occlusal variation between individuals; and the effects of wear on the dentition. The Yuendumu cast collection, representing a population with limited exposure to European customs and dietary habits, continues to attract the Adelaide School of Dentistry many interstate and overseas researchers interested in genetic and environmental influences on human dental development.     

The relationship of dental crowding to tooth size, dental arch width, and arch depth

This study was undertaken to answer the question, "Are there any differences in the mesiodistal tooth diameters, dental arch width and dental arch depth between the crowded and noncrowded dentitions?" The materials submitted for study consisted of the Orthoscan intraoral occlusograms of 89 subjects with well-aligned dentition and those of 74 subjects with gross dental crowding. The tooth size and arch dimensions were measured from these intraoral occlusograms. The data were subjected to statistical treatment for comparison of noncrowded and crowded groups. The findings in this study lead to the following conclusions: The mesiodistal tooth diameters of the crowded group were significantly larger than those of the noncrowded group. The dental arch widths of the crowded group were significantly smaller than those of the noncrowded group. No substantial or significant difference in dental arch depth between the crowded and noncrowded subjects could be noted. From these findings it seems that tooth size and dental arch width are determining factors in the formation of dental crowding. Clinically, these results suggest that in the treatment of dental crowding, extraction of teeth and/or expansion of dental arches should be considered depending on what is the main causative factor.     

A study of the taxonomic significance of the dental arch.

Sixteen dimensions were measured from the maxillary and mandibular dental arches of different ethnic groups of man, apes and monkeys. Multivariate analysis showed that discrimination was possible among the ethnic groups of man on the one hand and between the ape and monkey samples on the other. Nevertheless, the actual degree of discrimination between the primate samples depended upon whether the maxillary or mandibular arch dimensions were analysed. Furthermore, subsequent inclusion of the dental arch dimensions of fossil hominoid samples into the analysis confirmed the taxonomic significance of the dental arch, although its importance must await the acquisition of the more non-human primate data.     

Accuracy in Dental Medicine,A New Way to Measure Trueness and Precision

Reference scanners are used in dental medicine to verify a lot of procedures. The main interest is to verify impression methods as they serve as a base for dental restorations. The current limitation of many reference scanners is the lack of accuracy scanning large objects like full dental arches, or the limited possibility to assess detailed tooth surfaces. A new reference scanner, based on focus variation scanning technique, was evaluated with regards to highest local and general accuracy. A specific scanning protocol was tested to scan original tooth surface from dental impressions. Also, different model materials were verified. The results showed a high scanning accuracy of the reference scanner with a mean deviation of 5.3 ± 1.1 µm for trueness and 1.6 ± 0.6 µm for precision in case of full arch scans. Current dental impression methods showed much higher deviations (trueness: 20.4 ± 2.2 µm, precision: 12.5 ± 2.5 µm) than the internal scanning accuracy of the reference scanner. Smaller objects like single tooth surface can be scanned with an even higher accuracy, enabling the system to assess erosive and abrasive tooth surface loss. The reference scanner can be used to measure differences for a lot of dental research fields. The different magnification levels combined with a high local and general accuracy can be used to assess changes of single teeth or restorations up to full arch changes.     

Osteology of a slave burial population from Barbados,West Indies

A unique seventeenth–nineteenth century slave cemetery population from Newton plantation, Barbados, allows examination of craniodental characters in relation to ethnohistorical data. Age-at-death estimates suggest life expectancy at birth of 29 years and low infant mortality; historical demography, however, suggests life expectancy of 20 years and very high infant mortality. Tooth decay, bilateral tooth loss, periodontal disease, root hypercementosis, and severe enamel hypoplasia are high in frequency. The teeth yield evidence of such cultural practices as pipe-smoking and incisor mutilation. Several skeletal features reflect periodic near-starvation. Directional and fluctuating dental asymmetry, relative tooth size, and hypoplasia distribution suggest slaves experienced considerable weaning trauma; metabolic stress at this time exceeded that of prenatal and immediate postnatal periods. Odontometrics and dental and cranial nonmetric traits indicate that modern Blacks are intermediate between the ancestral slaves and modern Whites but more similar to the latter, suggesting effects of environmental covariance exceed those of genetic admixture. Nonmetric trait distributions show nonrandom patterns according to area of burial in the cemetery, a possible result of family segregation.     

Embryological development of Salvator merianae (Squamata: Teiidae)

Here we describe the embryonic development of Salvator merianae external morphologic features, as based on observation of 28 embryos across different days of incubation at 31 ± 0.5°C. Observed developmental stages were grouped and classified into the early, middle, and late periods. The early period (Stages 3–11) is distinguished by the origin of the encephalic vesicles, sensory placodes, pharyngeal arches, and degree of body flexion and rotation. The medium period (Stages 8–15) is distinguished by limb differentiation and by cranium‐facial characteristics. The late period (Stages 15–18) is determined by scale patterns, pigmentation, and embryo growth.     

Oral and general health status in patients treated in a dental consultation clinic of a geriatric ward in Bern, Switzerland

doi: 10.1111/j.1741‐2358.2011.00529.x Oral and general health status in patients treated in a dental consultation clinic of a geriatric ward in Bern, Switzerland Introduction: This audit reports on the oral and general health of patients who were treated in a dental consultation clinic of a geriatric hospital. Material and Methods: Dental and medical records were obtained from 112 female and 80 male patients (mean age, 83.7 ± 8.2 years) who attended a dental consultation. Data analysis included the general health [American Society of Anesthesiologists (ASA) classification, number of diagnoses, cognitive function] and dental state in the age strata 60–69, 70–79, 80–89 and 90–99 years. Results: Seventy‐four per cent of patients were aged over 80 years. The prevalence of ASA‐P4 and P3 varied between age groups. Most patients (>86%) had more than three chronic diseases. Cognitive impairment was present in almost half of both older age cohorts (43 and 50%). Half of the patients (52%) were edentulous. In dentate patients, the average number of teeth was 12 ± 6 and differed in the maxilla significantly between age groups (p = 0.005). There was no significant association between dental state, ASA classification and systemic conditions. Conclusions: The profile of this cohort reflects a poor oral and general health status. The results underline the importance of an interdisciplinary consultation in a geriatric ward where oral health care is an integral part.     

Development of the helicoidal plane

In this study of thebelicoidal occlusal plane the relationships between tooth wear, the transverse slopes of mandibular molars and dental arch breadths were examined in 74 pre-contemporary Australian Aboriginal skulls. With increasing age and tooth wear the orientation of the mandibular occlusal surfaces increased towards the buccal. The differential occlusal orientation from first to third molars, present at eruption, tended to increase progressively with tooth wear. These functionally induced changes, together with regional differences in relative breadths of the maxillary and mandibular dental arches, are important in the development of abelicoidal occlusal plane.     

Hopping and swimming in the leopard frog Rana pipiens: II. A comparison of muscle activities

Electromyography (EMG) was used to examine muscle activity of the major hip, knee, and ankle extensors during both hopping and swimming in leopard frogs. Chronic EMG electrodes were implanted for periods of 7–10 days. This permitted us to record EMG activities during both hopping and swimming from the same electrode, allowing a direct comparison of the timing and amplitudes of muscle activity between the two behaviors. We could then relate these activities to the kinematics of locomotion. In both behaviors, all three extensors were synchronously activated 30–50 ms before limb extension began. However, the hip extensor turned on relatively earlier in hopping than in swimming when on time was expressed as percent of stride. The hip and knee extensors were activated relatively longer in hopping and the ankle extensor relatively longer in swimming. The amplitudes of the rectified, integrated EMG signals were roughly twice as large in hopping as in swimming for all three muscles, supporting the notion that propulsion in hopping requires more force than in swimming. The EMG burst durations differed little between the muscles or, in relative duration, between the behaviors. As has been found in other quadrupeds, the EMG bursts began before visible movement and ceased at or before hindlimb extension was completed. In our animals, however, we found a consistent, low level (10–30% of maximum amplitude) of EMG activity that continued 60–200 ms past the end of the burst and into the suspension periods in both hopping and swimming. We hypothesize that this unusual activity may be present in frogs so that the hind limb remains aero(hydro)dynamically stable as the frog arches through its leap or glides in swimming following completed limb extension. Thus, the timing and pattern of the EMG bursts are consistent with those present in other tetrapods and support conservatism of neural control. However, the prolonged low-level activity suggests flexibility in the control pattern and variation according to specific behaviors. © 1996 Wiley-Liss, Inc.     

Dental arch form in the cercopithecidae

The dental arches of the major genera of Old World monkeys (superfamily Cercopithecoidea) were studied by morphometric techniques. Bicanine and bimolar breadths and arch lengths were ascertained for maxillary and mandibular arches. This data was then subjected to a variety of statistical tests. Corresponding arch dimensions of the upper and lower dentition showed the highest correlations, while the lowest correlations were generally observed between comparisons of arch dimensions and body size. A new expression was developed, relative male palate size (RMPS), which quantified the degree of sexual dimorphism while correcting for body size. The four hierarchies examined using RMPS values were sexual dimorphism, modes of sexual selection and predator defense and diet. Maxillary bicanine breadth was the only parameter that exhibited sexual dimorphism consistently in each of the four hierarchies, although differences in arch size were identified for diet and predator defense. Species grouped by predator defense showed the most sexual dimorphism in arch parameters.