Principles of occlusion in complete dentures
Occlusion is one of the most controversial subjects in dentistry and also one of the most important. Dental schools spend very little time teaching occlusal concepts, leaving a huge void in our knowledge of this critical area. After graduation, most of the sources of occlusal education teach the subject in manners that overburden learners with complicated, multimodule curricula, and strict philosophies. These approaches often make the process of treating occlusion appear more complicated than it should be. At the same time, occlusal disease in its many forms continues to ravage our patients’ teeth, making it the number one reason why our restorations fracture and fail.
It is a great service for our patients, and a great asset to clinical dentists, to understand how to provide a physiological and mechanically sound occlusion. Fortunately, giving our patients a sound occlusion is not as complicated as it may appear.
Dentists treat patients with a variety of occlusal approaches, from the incredibly meticulous and complicated gnathological approach with a fully adjustable articulator and cusp tripodation to a myofunctional approach all the way to the overly simplified and imprecise natural bite approach. Each modality has a number of followers who believe and feel deeply that the way they do dentistry is the correct way and may even view the other “occlusal camps” as inferior and/or inappropriate.
This intolerance and narrow-mindedness creates an environment that is conducive to neither dialogue nor consensus. The interesting point is, at all spectrums of the scale, clinicians report success and patients do well. Of course, each approach also has its downsides and failures. The differences from camp to camp are many. They start from such things as beliefs surrounding the position of the condyle to issues concerning when the bite needs to be changed. All of the buzzing coming out of the different camps makes many dentists want to just stay away from occlusal treatment altogether; unfortunately, that is impossible, since many things that a dentist does can affects the occlusion of a patient. Fortunately, there are some basic physiological and mechanical rules (or principles) that will apply to any camp, and they are equal to all: the “3 Golden Rules of Occlusion.”2,3
This article will discuss these relatively simple and scientific-based goals of occlusal therapy. The 3 Golden Rules of Occlusion make the goals of occlusal therapy very clear and simple to comprehend and to define. In addition, when we understand these rules and apply them, it becomes evident that occlusion is very mechanical and not as complicated as some wish to make it, and this should make occlusion less intimidating.4 Fulfilling these 3 rules will give our patients a physiologically and mechanically sound bite and the treating dentist clear goals to attain.
The 3 GOLDEN RULES OF OCCLUSION
The 3 Golden Rules of Occlusion can apply to any occlusal philosophy because they are sound physiological and mechanical principles that have been proven by both scientific research and common sense. Nevertheless, when the patient requires occlusal therapy, or when there is a need to reconstruct a bite, the most practical, anatomical, and physiological sound place to position the condyle is into the centric relation position.
The first Golden Rule is to have bilateral and even occlusal contact. The masticatory muscles can generate huge forces, often several hundred pounds of force per square inch.5 For this reason, bilaterally even contacts throughout the dentition are mechanically sound, allowing for proper load distribution and a stable occlusion. When a tooth interferes with full closure, it will trigger deflective interferences6-8 and cause any of the 7 signs and symptoms of occlusal disease such as hypersensitivity, abfractions, mobility, excessive wear or fractures, and muscle or temporomandibular (TM) pain. Posterior teeth deflections may create an occlusal avoidance pattern leading to excessive anterior tooth wear. Also, in order for muscles to function in coordination, teeth need to contact evenly. It is possible to induce muscle incoordination by introducing an occlusal interferences as shown by Sheikholeslam and Riise.9 Additionally, although controversial in the scientific literature, clinical experience shows that occlusal interferences in centric can trigger muscle or TM discomfort, and that removing them will bring about improvement of the symptoms.10
The second Golden Rule is posterior teeth disclusion, or anterior and canine guidance. Anterior and canine guidance allows for the immediate disclusion of molars and premolars when making lateral or protrusive movements, such as in chewing. This immediate posterior disclusion provides some important mechanical benefits, in that masticatory muscles significantly decrease activity and the amount of force applied to the anterior guiding teeth is greatly decreased.11,12 Williamson and Lundquist13 found that when posterior teeth touch, the muscles can function with full force. On the other hand, when only anterior teeth touch, the forces decrease significantly. An additional mechanical benefit is that since the mandible works as a Class III lever, the further a tooth is from the fulcrum (joint), the less force is applied to it. When a patient lacks this mechanical benefit, during lateral movements, the posterior teeth grind over each other with full muscular force, and it is typical to see these patients with severe signs and symptoms of occlusal disease.
Finally, the third Golden Rule of Occlusion is an unobstructed envelope of function.14 During the chewing motion, the mandible does not only swing laterally, it swings forward (protrusively) during the closure movement, returning back into the centric stop. This is called the envelope of function. It varies from patient to patient, but Lundeen and Gibbs15 found that the average was 0.37 mm. The correct amount of overjet allows the space for this protrusive movement to occur without interference. When the overjet is insufficient, or the lingual morphology of the anterior teeth is not concave enough, interference to the anterior path of closure will occur. The consequences of violating this principle while restoring anterior teeth are that patients may complain that their bite feels high or locked in. This often triggers parafunction activity. Also, this interference in the path of closure may cause a scraping of the anterior teeth, resulting in the typical wear pattern, severe “thinning” of incisal edges, or wear of the lingual surface of the maxillary anterior teeth with wear of the facial of mandibular anterior teeth. It can also cause other problems, including mobility, chipping, and fracture of the teeth.
CONCLUSION
Having a clear vision for what a healthy occlusal outcome should be for restorative dentistry is priceless, and the same is true for occlusal therapy. This clear vision, along with defined goals, will allow the clinician to make clear decisions during diagnosis. It will also allow the professional to measure results at the end of treatment, as well as address the severe and rampant problem of occlusal disease.
The 3 Golden Rules of Occlusion are clear, simple, scientifically sound principles. They are physiological and mechanical sound principles that allow the dentist to increase the quality and predictability of any dental procedure.
Occlusionis any joining of the teeth, a special case of articulation (A.Ya.Katts). The number of occlusion is great. The most important of them in practice are fourocclusions: centralocclusion, anterior and two lateral (left and right) occlusions.
It is clear thatocclusion being clinical expression of the chewing movements, breaks up into separate phases according to kinds of the chewing movements. The chewing movements of the mandible as well as its general are divided into sagittal, transversal and vertical. In this connection occlusion phases or phases of the dentitions should also be divided into sagittal (anteroposterior), transversal (lateral) and vertical (central). It coincides with division of the chewing process into three phases:
1) a phase of gripping and cutting of food which is characterized by sliding of the cutting edges of the lower anterior teeth along the palatine surfaces upward to their regional joining and backward; sagittal movement prevails in this phase and, hence, sagittalocclusion;
2)the phase of food crushing which is carried out by the vertical movement of the mandible and characterized by the maximal contact of the teeth of both jaws; occlusion of dentitions in this phase has received the name of central and is the initial and final moment of all chewing movements of the mandible;
3) the phase of grinding food which is characterized by alternating movements of the mandible to the sides. In movement of the mandible in any side the tubers of the masticatory teeth of the mandible will contact with same tubers of the maxilla (buccal with buccal, palatal with lingual) on this side.
The word “articulation” is derived from anatomy where it designates a joint, articulation, however many authors give different meaning to this word. In our dentistry the definition of this term given by A.J.Kats is of the greatest use – articulation is every possible positions and movements of the mandible in relation to the maxilla carried out by means of the chewing muscles.
This definition of articulation includes not only chewing movement of the mandiblebut also its movement during conversation, yawning, etc. For practical purposes it is most convenient to define articulation as a chain of variants of occlusion replacing each other. Such definition is more concrete, i.e. covers only chewing movements of the mandiblewhich studying is very important for construction of special devices reproducing them – articulators.
Occlusion is joining of dentitions on the whole or by separate groups of the teeth during a greater or smaller interval of time.
Thus, occlusion is considered to be a special case of articulation, one of its moments.
Four basic kinds of occlusion are distinguished: central, anterior and lateral (right and left).
Central occlusion is characterized by joining teeth at a maximum quantity of contacting points.
Signs of centralocclusion:
– the midline of the face coincides with a line passing between the central incisors;
– articular heads are located on the slope of the articular tubercle at its basis.
There is simultaneous and uniform contraction of the masticatory and temporal muscles on either side.
In the anterior occlusion there is a moving out of the mandibleforward. It is achieved by bilateral contraction of the lateral pterygoid muscles.
Signs of anterior occlusion:
– The midline of the face coincides with the midline which passes between the incisors;
– The articular heads in anterior occlusion are displaced forward and located at the top of the articular tubercles.
Lateral occlusion arises in moving of the mandibleto the right (right occlusion) or to the left (left occlusion).
Signs of lateral occlusion:
– in displacement of the mandible to the right the articular head remains at the basis of articular tubercle on the side of displacement, slightly rotating. On the left side the articular head is located at the top of the articulate tubercle;
– right lateral occlusion is accompanied by contraction of the lateral pterygoid muscles of the opposite (left) side and, on the contrary, left lateral occlusion – contraction of the same muscle of the right side.
Condition of relative rest of the mandible.
If there is no chewing and talking dentitions are usually open, i.e. the mandiblehangs and a lumen of 1-6 mm in size is observed between frontal teeth. In dropping of the jaw the muscles are a little stretched that causes irritation of the proprioceptors.
The study of dental occlusionis important aspect of dentistry. The study and practice of most branches of dentistry should be based on a strong foundation of the knowledge of occlusion.Orthodontics is no exception to this as many changes occur in the occlusion during orthodontic therapy. The orthodontist should know what constitutes normal occlusion in order to be able to recognize abnormal dental occlusion.
Angle defined occlusion as the normal relation of the occlusal inclined planes of the teeth when the jaws are closed. This definition is an over-simplification of what it actually constitutes.
It necessitates tonic contraction of the muscles which keeps the jaw in the specified position. Various groups of fibers are alternatively contracted in the masticatory muscles that providerest and at the same time allow to be ready to new contraction. Energy expenses of the muscles under the condition of relative physiological rest are minimal. The width of the lumen between the central incisors in position of rest of the mandibleis individually various. There are data that it increases with the years. Besides the position of relative rest of the mandibleis an expedient reflex act (an alternating masticatory pressure is physiological for the periodontium whereas constant rest would cause its ischemia and development of dystrophy).
Position of the rest of the mandibleis a protective congenital reflex. It is initial and final for all its movements.
Occlusion is a complex phenomenon involving the teeth, periodontal ligament, the jaws, the temporomandibular joint, the muscles and the nervous system. The aim of this article is to throw light oormal occlusion and to highlight the orthodontic aspects of dental occlusion.
Ideal occlusion: It is a pre-conceived theoretical concept of occlusal structural & functional relationships that includes idealized principles & characteristics that a dental occlusion should have.
Physiological occlusion: This refers to an occlusion that deviates in one or more ways from ideal yet it is well adapted to that particular environment, and is aesthetic and shows no pathological manifestations or dysfunction.
Balanced occlusion: A dental occlusion in which balanced and equal contacts are maintained throughout the entire arch during excursions of the mandible.
Functional occlusion: It is defined as an arrangement of teeth which will provide the least efficiency during all the excursive movements of the mandible which are necessary during function.
Therapeutic occlusion: A dental occlusion that has been modified by appropriate therapeutic modalities in order to change a non-physiological occlusion to one that is at least physiological if not ideal.
Traumatic occlusion: Traumatic dental occlusion is an abnormal occlusal stress which is capable of producing or has produced an injury to the periodontium.
Trauma from occlusal: It is defined as periodontal tissue injury caused by occlusal forces through abnormal occlusal contacts.
Types of Cusps
The human posterior teeth constitute two types of cusps. They are the centric holding cusps and the non- supporting cusps.
Centric holding cusps
The facial cusps of mandibular and palatal cusps of maxillary posterior teeth are called the centric holding cusps. They occlude into the central fossae and marginal ridges of opposing teeth. They are also called the stamp cusps.
Non supporting cusps
The maxillary buccal and mandibular lingual cusps are called non-supporting cusps. They contact and guide the mandible during lateral excursions & shear food during mastication. Hence they are also called hearing or guiding cusps.
Arrangement of Teeth in Humans
Human dentition exhibits two types of tooth arrangement when the upper and lower teeth occlude with one another. They are:
a. Cusp fossa occlusion
b. Cusp embrasure occlusion
Cusp- fossa occlusion
In this type of dental occlusion, the stamp cusp of one tooth occludes in a single fossa of a single opponent. The upper stamp Cusps fit into all except the mesial fossae of the lower teeth while the lower stamp cusps fit into all the upper fossae except the distal ones of bicuspids.
This kind of arrangement where contacts occur between single opposing teeth is called a cusp-fossa dental occlusion or a tooth to tooth arrangement
Cusp-embrasure occlusion
Another type of dental occlusion between the upper and lower teeth is called the cusp-embrasure or tooth to two teeth occlusion. In this type of arrangement each tooth occludes with two opposing teeth.
Centric relation (not centric occlusion)is the relation of the mandible to the maxilla when the mandibular condyles are in the most superior and retruded position in their glenoid fossa with the articular disc properly interposed.
Centric relation is also called ligamentous position or terminal hinge position. At centric relation both the condyles are simultaneously seated most superiority in their glenoid fossa.
In trying to obtain centric relation the mandible may be forced too far back, thus the term unstrained appears in some definitions.
Centric occlusion is that position of the mandibular condyle when the teeth are in maximum intercuspation. Centric occlusion is also called inter-cuspal position or convenience occlusion.
Centric relation and centric occlusion should coincide in order to have perfect harmony between the teeth, the temperomandibular joint and the neuromuscular system. Some studies have shown that majority of the population have a maximum inter-cuspation 1 —2 mm forward of centric.
Maximum cuspation can also occur without being in centric. This is called maximum intecuspation, habitual occlusion or acquired occlusion.
Centric Contacts
They are areas of the teeth that contact the opposing teeth. Centric contacts have been classified into posterior centric contacts and anterior centric contacts.
Posterior centric contacts
The posterior centric contacts consist of the facial range of contacts and the lingual range of contacts. Facial range of posterior centric contacts involve the mandibular Facial cusp tips contacting the central fossae and mesial marginal ridges of the opposing maxillary teeth.
Lingual range of posterior centric occlusion involve the maxillary lingual cusp tips contacting the central fossae and distal marginal ridges of the opposing mandibular teeth.
Anterior centric contacts
Anterior teeth have one range of centric contacts and are in line with facial range of posterior centric contacts.
Posterior centric contacts result in axially directed forces as convex cusp tips occlude on an opposing tooth area that is perpendicular to the force.
However centric contacts often occur in inclines of posterior teeth. These contacts that occur on inclines are called poded centric contacts.
The contacts occurring on inclines should be balanced by an equal contact on an opposing incline to resolve the forces in an axial direction. If the contacts occur on two inclines, the contact is termed bi-poded contact.
Contacts (not centric occlusion) that occur on three inclines are called triopoded contacts. Contacts that occur on four inclines are called quadra-poded contacts.
Occlusion, in a dental context, means simply the contact between teeth. More technically, it is the relationship between the maxillary (upper) and mandibular (lower) teeth when they approach each other, as occurs during chewing or at rest.
Malocclusion is the misalignment of teeth and jaws, or more simply, a “bad bite”. Malocclusion can cause a number of health and dental problems.
Malocclusion is the result of the body trying to optimize its function in a dysfunctional environment. It can be associated with a number of problems, including crooked teeth, gum problems, the temporomandibular joint (TMJ), and jaw muscles. Teeth, fillings, and crowns may wear, break, or loosen, and teeth may be tender or ache. Receding gums can be exacerbated by a faulty bite. If the jaw is mispositioned, jaw muscles may have to work harder, which can lead to fatigue and or muscle spasms. This in turn can lead to headaches or migraines, eye or sinus pain, and pain in the neck, shoulder, or even back. Malocclusion can be a contributing factor to sleep disordered breathing which may include snoring, upper airway resistance syndrome, and / or sleep apnea (apnea means without breath). Untreated damaging malocclusion can lead to occlusal trauma.
Some of the treatments for different occlusal problems include protecting the teeth with dental splints (orthotics), tooth adjustments, replacement of teeth, medication (usually temporary), a diet of softer foods, TENS to relax tensed muscles, and relaxation therapy for stress-related clenching. Removable dental appliances may be used to alter the development of the jaws. Fixed appliances such as braces may be used to move the teeth in the jaws. Jaw surgery is also used to correct malocclusion.
Static occlusion refers to contact between teeth when the jaw is closed and stationary, while dynamic occlusion refers to occlusal contacts made when the jaw is moving. Dynamic occlusion is also termed as articulation. During chewing, there is no tooth contact between the teeth on the chewing side of the mouth.
Centric occlusion is the occlusion of opposing teeth when the mandible is in centric relation. Centric occlusion is the first tooth contact and may or may not coincide with maximum intercuspation. It is also referred to as a person’s habitual bite, bite of convenience, or intercuspation position (ICP). Centric relation, not to be confused with centric occlusion, is a relationship between the maxilla and mandible.
Andrews’ Six keys of Occlusionare:
Molar inter-arch relationship
Mesio-distal crown angulation
Labio-lingual crown inclination
Absence of rotation
Tight contacts
Curve of Spee
Molar inter-arch relationship
The mesio-buccal cusp of the upper first molar should occlude in the groove between the mesial and medial buccal cusp of the lower first molar. The mesio-lingual cusp of the upper first molar should occlude in the central fossa of lower first molar. The crown of the upper first molar must be angulated so that the distal marginal ridge occludes with the mesial marginal ridge of lower second molar. This is first key of Andrew’s Six Keys.
Mesio-distal crown angulation
The second key makes use of a line that passes along the long axis of the crown through the most prominent part in the center of the labial or buccal surface. this line is called the long axis of the clinical crown.
For the occlusion to be considered normal, the gingival part of the long axis of the crown must be distal to the occlusal part of the line. Different teeth exhibit different crown angulation.
Labio-lingual crown inclination
The crown inclination is determined from a mesial or distal view. If the gingival area of the crown is more lingually placed than the occlusal area, it is referred to as positive crown inclination. In case the gingival area of the crown is more labially or buccally placed than the occlusal area it is referred to as negative crown inclination.
The maxillary incisors exhibit a positive crown inclination while the mandibular incisors show a very mild negative crown inclination. The maxillary and mandibular posteriors have a negative crown inclination.
Absence of rotation
Normal occlusion is charecterized by absence of rotation. Rotated posterior teeth occupy more space in the dental arch while rotated incisors occupy less space in the arch.
Tight contacts
To consider an occlusion as normal, there should be tight contact between adjacent teeth.
Curve of Spee
A normal occlusal plane according to Andrews should be flat, with the curve of Spee not exceeding 1.5mm.
Curve of Wilson a curve that contacts the buccal & lingual_cusp tips of the mandibular buccal teeth.
The Curve of Wilson is medio-Iateral on each side of the arch.
It results from inward inclination of the lower posterior teeth. Curve of Wilson helps in two ways
a. Teeth are aligned parallel to the direction of medial pterygoid for optimum resistance to masticatory forces.
b. The elevated buccal cusps prevent food from going past the occlusal table.
It refers to the antero-posterior curvature of the occlusal surfaces beginning at the tip of the lower cuspid & following the cusp tips of the bicuspids & molars continuing as an arc through the condyle.
If the curve is extended, it would form a circle of about 4 inch diameter. This is not in the case of Curve of Wilson.
The curve results from variation in axial alignment to the lower teeth. The long axis of the each lower teeth is aligned nearly parallel to its individual arc of closure around the condylar axis.
This requires a gradual progressive increased mesial tilting of teeth towards molars which creates the curve of Spee
The curve of Monson is obtained by extending the curve of Spee & Curve of wilson to all cusps & incisal edges.
A malocclusion is a misalignment of teeth or incorrect relation between the teeth of the two dental arches. The term was coined by Edward Angle, the “father of modern orthodontics”, as a derivative of occlusion, which refers to the manner in which opposing teeth meet.
Malocclusion is a common finding, although it is not usually serious enough to require treatment. Those who have more severe malocclusions may require orthodontic and sometimes surgical treatment (orthognathic surgery) to correct the problem. Correction of malocclusion may reduce risk of tooth decay and help relieve excessive pressure on the temporomandibular joint. Orthodontic treatment is also used to align for aesthetic reasons.
Malocclusions may be coupled with skeletal disharmony of the face, where the relations between the upper and lower jaws are not appropriate. Such skeletal disharmonies often distort sufferer’s face shape, severely affect aesthetics of the face and may be coupled with mastication or speech problems. In these cases the dental problem is, most of the time, derived from the skeletal disharmony. Most skeletal malocclusions can only be treated by orthognathic surgery.
Classification
Depending on the sagittal relations of teeth and jaws, malocclusions can be divided mainly into three types according to Angle’s classification method. However, there are also other conditions, e.g. crowding of teeth, not directly fitting into this classification.
Many authors have tried to classify or modify Angle’s classification. This has resulted in many subtypes.
Angle’s classification method
Class I with severe crowding and labially erupted canines
Class II molar relationship
Edward Angle, who is considered the father of modern orthodontics, was the first to classify malocclusion. He based his classifications on the relative position of the maxillary first molar. According to Angle, the mesiobuccal cusp of the upper first molar should align with the buccal groove of the mandibular first molar. The teeth should all fit on a line of occlusion which, in the upper arch, is a smooth curve through the central fossae of the posterior teeth and cingulum of the canines and incisors, and in the lower arch, is a smooth curve through the buccal cusps of the posterior teeth and incisal edges of the anterior teeth. Any variations from this resulted in malocclusion types. It is also possible to have different classes of malocclusion on left and right sides.
Class I: Neutrocclusion Here the molar relationship of the occlusion is normal or as described for the maxillary first molar, but the other teeth have problems like spacing, crowding, over or under eruption, etc.
Class II: Distocclusion (retrognathism, overjet) In this situation, the upper molars are placed not in the mesiobuccal groove but anteriorly to it. Usually the mesiobuccal cusp rests in between the first mandibular molars and second premolars. There are two subtypes:
Class II Division 1: The molar relationships are like that of Class II and the anterior teeth are protruded.
Class II Division 2: The molar relationships are class II but the central are retroclined and the lateral teeth are seen overlapping the centrals.
Class III: Mesiocclusion (prognathism, negative overjet) In this case the upper molars are placed not in the mesiobuccal groove but posteriorly to it. The mesiobuccal cusp of the maxillary first molar lies posteriorly to the mesiobuccal groove of the mandibular first molar. Usually seen as when the lower front teeth are more prominent than the upper front teeth. In this case the patient very often has a large mandible or a short maxillary bone.
Crowding of teeth
Crowding of teeth is where there is insufficient room for the normal complement of adult teeth.
Causes
Extra teeth, lost teeth, impacted teeth, or abnormally shaped teeth have been cited as causes of malocclusion. A small underdeveloped jaw, caused by lack of masticatory stress during childhood, can cause tooth overcrowding. Ill-fitting dental fillings, crowns, appliances, retainers, or braces as well as misalignment of jaw fractures after a severe injury are other causes. Tumors of the mouth and jaw, thumb sucking, tongue thrusting, pacifier use beyond age 3, and prolonged use of a bottle have also been identified as causes.
In an experiment on two groups of rock hyraxes fed hardened or softened versions of the same foods, the animals fed softer food had significantly narrower and shorter faces and thinner and shorter mandibles than animals fed hard food. Experiments have shown similar results in other animals, including primates, supporting the theory that masticatory stress during childhood affects jaw development. Only one small study has investigated this effect in humans. Children chewed a hard resinous gum for two hours a day and showed increased facial growth.
A 2011 paper suggested that “the changes in human skulls are more likely driven by the decreasing bite forces required to chew the processed foods eaten once humans switched to growing different types of cereals, milking and herding animals about 10,000 years ago.”
Treatment
Crowding of the teeth is treated with orthodontics, often with tooth extraction, Invisalign, or dental braces, followed by growth modification in children or jaw surgery (orthognathic surgery) in adults. Surgery may be required on rare occasions. This may include surgical reshaping to lengthen or shorten the jaw (orthognathic surgery). Wires, plates, or screws may be used to secure the jaw bone, in a manner similar to the surgical stabilization of jaw fractures. Very few people have “perfect” alignment of their teeth. However, most problems are very minor and do not require treatment.
Other condition
Open bite treatment after eight months of braces
Other kinds of malocclusions are due to vertical discrepancies. Long faces may lead to open bite, while short faces can be coupled to a deep bite. However, there are many other more common causes for open bites (such as tongue thrusting and thumb sucking), and likewise for deep bites.
Malocclusions can also be secondary to transverse skeletal discrepancy or to a skeletal asymmetry.
Etiology
Oral habits and pressure on teeth or the maxilla and mandible are etiological factors in malocclusion.
In the active skeletal growth mouthbreathing, finger sucking, thumb sucking, pacifier sucking, onychophagia (nail biting), dermatophagia, pen biting, pencil biting, abnormal posture, deglutition disorders and other habits greatly influence the development of the face and dental arches.
Pacifier sucking habits are also correlated with otitis media.
Dental caries, periapical inflammation and tooth loss in the deciduous teeth alter the correct permanent teeth eruptions.
