The canine is a tooth with special characteristics and adaptive significance that varies considerably between mammalian lines and the primates. No matter what the line, canine teeth are never involved in mastication and do not interfere with masticatory dynamics. Mastication, which is one of the most complex functions that monkeys and apes display, appears well before the large canines in both phylogeny and ontogeny. In apes, their size and shape have nothing to do with diet, but are linked to sexual selection. The human line of hominids possesses smaller canines that have become incisiform and have lost their sexual and social function. They are now used exclusively to tear apart meat and other types of solid foods. The development of a wide, short buccal surface that increased medial-lateral movement during the masticatory cycle, may explain this particular development in recent hominids including humans. From an evolutionary point of view this means that the human canine has been subjected to stresses imposed by the biomechanical environment of the masticatory apparatus. In other words, the human canine, as well as those of the other anthropoids, does not guide mastication but has acquired a morphology and position restricted by masticatory functions. In evolutionary terms, it is therefore referred to as an “exaptation”; it has acquired, not a function, but a passive characteristic which makes it a marker for rehabilitation – on condition that its eruption is related to normal masticatory functions in individual histories, but it never serves as a mediator of mastication.

There are many ways dentists can restore teeth prosthetically. Depending on its condition of relative integrity or more serious breakdown and the patient’s loss of other teeth, the practitioner can choose from a variety of quite different procedures ranging from the fabrication of a single ceramo-ceramic crown on a vital tooth to correction of considerable loss of teeth with an implant supported bridge. This paper will evaluate most of these treatment modalities and, in addition to purely prosthetic considerations, will discuss the integration into treatment of periodontal, implant, occlusal, and functional concepts.

The morphological particularities of the posteriorly rotated mandible, first described by A. Björk, may correspond to extremely variable clinical situations. We can derive important information by analyzing the forms and proportions of different mandibular entities. This article proposes to illustrate the most frequently encountered situations by describing a number of cases of posterior rotation and by explaining how Delaire’s architectural analysis can be used in clinical practice.

The exchange of position of two adjacent teeth constitutes a transposition. Maxillary canines are rarely affected; transpositions of upper canines occur in only .2% of the orthodontic population. They can be detected early in radiographic examinations and later, clinically, after they begin to erupt. Most writers affirm that transpositions, which are often associated with other dental anomalies, are caused primarily by some genetic defect but that local factors may contribute to their development. Practitioners should consider their muco-gingiva environment as an important factor in their evaluation of the iatrogenic risks that might accompany treatment and consider improving soft tissue status as a preparatory soft tissue therapeutic procedure. They must also differentiate between cases of incomplete transposition and partial complete transposition, which can almost always be successfully treated, from cases of total complete transposition that are relatively difficult if not impossible to treat.

In this paper we examine the placement of the human canine tooth in the dento-alveolar system in order to explain its phylogenesis and ontogenesis over the course of its interactions with other tissues. We explain the known genetic mechanisms that occur throughout its morphogenesis and during its eruption until the tooth takes its place in the oral cavity. We carefully examine the role that genetic and environmental factors play in causing anomalies in its form, maturation, eruption and function.

We show how environmental factors determine how well it becomes integrated into the already established dental functional schema.

The increasing number of questions posed by problems arising from the behavior of teenagers make it logical for us to ask whether or not we should consider adolescence to be a disease. The answer is obvious: of course not! And we can affirm that response with empirical evidence. Most adolescents we see in consultation do well without having any need for psychiatric assistance, an observation confirmed by a French Ministry of Health 2002 study that found only one out of eight adolescents suffered from mental disorders. This, of course, clearly implies that seven out of eight enjoy good mental health.

If adolescence is not a disease, it could become one if friends and families of teenagers fail to understand the profound changes these young people are passing through or misinterpret the manifestations of this crucial life stage.

The use of distraction osteogenesis to improve the airway volume of individuals affected by craniofacial anomalies is common practice today. The methods of assessing the outcomes of such surgical procedures have changed over the last several years.

Objective : The objective of the present pilot study was to determine if the CBCT imaging modality may serve as a simple and reliable method for craniofacial practitioners to evaluate airway volume changes following distraction osteogenesis.

Materials and Methods : Twelve patients who had previously undergone distraction osteogenesis for the primary purpose of improving their airways were enrolled in the current study. Pre (T0) and post-surgical (T1) CBCT’s volumes were analyzed to measure the nasopharyngeal (NP) and oropharyngeal (OP) volume changes. InVivoDental 4.0 (Anatomage Inc., San Jose, CA) (IVD) program was used to visualize and render the oropharyngeal (OP) and nasal passage (NP) volumes, separately. Means and standard deviations were calculated.

Results : Of the 7 males and 5 females in the study, 4 patients underwent mandibular distraction (MandDO) and 8 underwent maxillary distraction (MaxDO). Four in the MaxDO group were treated with internal distractors and 4 were treated with external distractors. Individuals who underwent internal MaxDO greatly improved their NP volumes (1605 ± 1736 to 3273 ± 3130 mm3) as did patients who underwent external MaxDO (5763 ± 5077 to 9243 ± 9442 mm3). In comparison, the MandDO group’s NP volume showed modest gains (3519 ± 1944 to 3894 ± 2516 mm3). With regard to the OP volumes, the MandDO group gained substantially (4906 ± 2347 to 11385.8 ± 6393.5 mm3) while the MaxDO groups showed humble increases; internal MaxDO group (1779 ± 273.8 to 2639.5 ± 898.4 mm3) and the external MaxDO group (8959 ± 5311 to 9734.13 ± 7124.7 mm3).

Conclusions : In the present preliminary study of assessing airway volume changes using CBCT on patients who have undergone different DO techniques, MandDO greatly increases OP volumes and MaxDO tends to increase NP volumes. The CBCT imaging modality holds great promise for craniofacial practitioners in its application to assess airways of individuals affected by craniofacial anomalies.

Measurements of nasal resistance do not give an exhaustive functional assessment of nasal breathing function. Nevertheless, an increase in its thermal endocranial exchanges during its operation, which are regulated specifically by respiratory nasal mucosa, can be utilized to construct an operative physiological definition of nasal breathing at a state of optimal rest. These precise assessments, in elucidating the etiology of oral-nasal malformations, can give a clear picture of the morphological characteristics that orthodontists should strive to optimize as the face develops over the course of their treatment of malocclusions.

In treating children who have a significant lack of space both for the correct placement of their teeth, in what is called an arch length discrepancy, as well as for proper accommodation of their airways resulting in the Obstructive Sleep Apnea Syndrome, it seems to us to be indispensable for specialists in dentofacial orthopedics and otolaryngology to share and combine their philosophies and treatment approaches. The three clinical cases that we are presenting in a virtually documentary cinemaphotographic fashion, dealing simultaneously with the skeletal, dental, and breathing aspects of the disorder, will, we hope, give an improved view of the landmarks and architecture of “facial insufficiency” and the ways in which it can be treated. Patients with “facial insufficiency” suffer from simultaneous impairment of the correct growth off the two maxillae. In addition, the failure of the two jaws to develop sagittally makes the problem difficult to detect. Patients with Class I bimaxillary retrusions make up the majority of patients seeking orthodontic treatment who have facial insufficiency. And it is only the oral examination the orthodontist makes about the lack of space for teeth that uncovers the accompanying problem of lack of space for the airways. It should be pointed out that not all patients with bimaxillary retrusions have insufficient airway space. Still orthopedic treatment of the dental problem, enlarging available space in the dental arches, also automatically increases available airway space. This procedure must await the restart of vertical posterior growth under the influence of upward pressure from the tongue against palatal supports that stimulate the mandibular condyles. It is understandable, then, that any blockage of nasal breathing, from, for example the inferior turbinates or enlarged adenoidal tissue or impediment to vertical tongue thrusts, from excess tonsilar tissue or tight lingual frenums would be a primary hindrance to the desired growth process. So the first orthodontic objective is freeing the tongue, the second is adjusting occlusion. Ramus growth, in fact, unlocks a verticotransverse “raising” action of the lower lateral sectors needed for occlusal recovery and advancement of the maxilla. The “mandibular lock” blocking maxillary advancement is thus opened vertically.

Biometric study of contemporary human maxillary incisors and canine coronal morphology

The orthodontic alignment or prosthetic rehabilitation of the upper anterior sector is based on available biometric data.

The aim of this study is to measure the angle formed between the functional lingual surface of the canine and central incisor and the axial-orbital plane.

Materials and methods

This retrospective study is based on an analysis of documents of young dental students.

The measurements were made on 49 silicone models of healthy, natural, functional teeth, in class I occlusion for the maxillary anterior group.

Results

The values of slope angulations of the lingual surfaces relative to the axial-orbital plane clearly decrease by 10° from the central incisor (57°) to the canine (47°).

If there is stability in buccal morphology, there is variability in anterior lingual morphology, particularly of the canine.

These variations in an essential zone on the functional level are marked enough to warrant being taken into account in clinical practice.

Impacted upper canines occur, in buccal or palatal sites, in about 3% of the population and pose a threat to neighbouring teeth. Before orthodontists can bring them into their proper positions in the arch, oral surgeons often have to uncover them. In this article we discuss the traction pathways, open or tunnelised, that orthodontists can then use to begin moving them. While orthodontists can use both techniques successfully, they should understand the advantages and disadvantages of both before making a decision.