Tooth eruption and movement - PDF Free Download

Tooth eruption and movement Dr. Krisztián Nagy

Diphydont dentition Deciduous dentition primary dentition

Diphydont dentition Permanent dentition secondary dentition

Mixed Dentition: Presence of both dentitions

Tooth eruption

Teeth are formed in relation to the alveolar process. Epithelial thickening: Dental lamina Enamel organs: Series of 10 local thickenings on dental lamina in each alveolar process. Each thickening forms one milk tooth.

Stages in the formation of a tooth germ

Formation of enamel organs

Stages Bud stage : Characterized by formation of a tooth bud. The epithelial cells begin to proliferate into the ectomesenchyme of the jaw.

Cap stage : Formation of dental papilla. The enamel organ & dental papilla forms the tooth germ. Formation of ameloblasts. Formation of odontoblasts.

Bell stage : The cells on the periphery of the enamel organ separate into three important layers: Cuboidal cells on the periphery of the dental organ form the outer enamel epithelium. The cells of the enamel organ adjacent to the dental papilla form the inner enamel epithelium. The cells between the inner enamel epithelium and the stellate reticulum form a layer known as the stratum intermedium. The dental lamina begin to disintegrates, leaving the developing teeth completely separated from the epithelium of the oral cavity.

Crown stage : 1. Mineralization of hard tissues occur. 2. The inner enamel epithelial cells change in shape from cuboidal to columnar. The nuclei of these cells move closer to the stratum intermedium and away from the dental papilla. 3. The adjacent layer of cells in the dental papilla suddenly increases in size and differentiates into odontoblasts, which form dentin. 4. The inner enamel epithelium and the formation of odontoblasts continue from the tips of the cusps.

Preeruption phase- crown phase

Origin of germs of permanent teeth

Preeruption phase

Root formation

Eruption phase movement

Eruption phase breakthrough

Eruption phase occlusal contact

Eruption cascade

Sequence of tooth eruption

05/1985 04/1987 11/1989 04/1991 09/1996 02/1999

Sequence of tooth eruption Age Tooth Girls Boys 6 y 6-6 5,94 6,21 6 + 6 6,22 6,40 1-1 6,26 5,54 7 y 1 + 1 7,20 7,47 2-2 7,34 7,70 8 y 2 + 2 8,20 8,26 10 y 3-3 9,86 10,79 4 + 4 10,03 10,40 4-4 10,18 10,82 11 y 5 + 5 10,88 11,18 5-5 10,89 11,47 3 + 3 10,98 11,69 12 y 7-7 11,66 12,12 7 + 7 12,27 12,68 18-22 y 8 +/- 8

Eruption phase occlusal contact 5 months At birth 1 year 2 years 3.5 years 4.5 years

Posteruption phase 7 years-functional occlusion attained but root apex is still not fully formed 15 years incisal wear

Some data The rate of tooth eruption depends on the phase of movement Intraosseous phase: 1 to 10 µm/day Extraosseous phase: 75 μm/day

Presurgical naso-alvolear molding

Bilateral cleft lip, alveolus and palate

Secondary cases 18 months 2 years

Abnormalities 1. Dentitio tarda 2. External resorption 3. General resorption disorders 4. Ankylotic primary teeth 5. Aplasia, oligodontia, hypodontia 6. Remaining primary teeth 7. Eruption disorders

Dentitio tarda

Dentitio tarda 6.5 year 9 year 10.5 year 12 year

External resorption

General resorption disorde

Eruption disorders hormonal Familial, nonsyndromic PFE is caused by heterozygous mutations in the gene encoding the G protein-coupled receptor for parathyroid hormone and parathyroid hormone-like hormone (PTHR1) - Decker et al., 2008

Submerged primary teeth

Ankylosis

Retained primary teeth

Aplasia / oligodontia Anodontia = primary dental aplasia Total anodontia ectodermal dysplasia Partial anodontia (oligodontia) Hypodontia (last missing) M3 10-25% P2 3-4% I2 2%

Congenitally Missing Teeth

Natal and Neonatal Teeth

Eruption disoders Frontal region Canine region Premolar region Molar region Wisdom tooth region

Supporting zone

Lost of support

Maintain space! Space maintainer Lip-bumper Transpalatinal-arch Lingual-arch

Tooth movement

Eqilibrium theory BITE TONGUE LIP, BUCCAL TISSUES ERUPTION

Dental movement Physiological: Eruption Pathological: Early primary or secondary tooth extraction Tumor Thumb sucking Muscular dysfunction Therapeutical: Orthodontics

Guidance with functional apparatus Fränkel III

Guidance with functional apparatus Lip bumper

Basic principles of orthodontics Bony appositon by traction and resorption on pressure Too much pressure will cause capillary compression and hyalinization Effective orthodontic force correlates with root surface Newton III. rule: Action=Reaction. It is impossible to move only one tooth, only with skeletal anchorage

Guided extrusion of impacted tooth

Box-loop

Skeletal anchorage Headgear

Skeletal anchorage Palatinal mini- implant Vestibular mini-implant

Forced extrusion in periodontally lost case Only traction bony apposition

Thank you very much for your kind attention! nagykrisztian@me.com

Histology Surrounding tissues The surrounding fibers change from being parallel to the tooth surface to bundles that are attached to the tooth surface and extending towards the periodontium (bone) The periodontal ligament have contractile properties and changes drastically during eruption During eruption, collagen fiber formation and turnover are rapid enabling fibers to attach and release and attach in rapid succession. Some fibers may attach and reattach later while the tooth moves occlusally as new bone forms around it and the fibers will organize and increase in number and density as the tooth erupts rxdentistry.net

Histology Underlying tissues As the tooth moves occlusally it creates space underneath the tooth to accommodate root formation Fibroblasts around the root apex form collagen that attach to the newly formed cementum Bone trabeculae fill in the space left behind as the tooth erupts in the pattern of a ladder which gets denser as the tooth erupts After tooth reaches functional occlusion periodontal fibers attach to the apical cementum and extend into the adjacent alveolar bone

Mechanisms of Eruptive Tooth Movement Eruption is a multifactorial process The accepted theories of tooth eruption are: 1. Root Formation. Should be an obvious cause of tooth eruption. But studies have not provided evidence for this. If a tooth that is continuously erupting (rodent incisor and guinea pig molar) is prevented the root still forms by causing bone resorption. Rootless tooth still erupt, some teeth erupt more than the total length of the roots and the teeth still erupt after completion of root formation. Therefore root formation is accommodated during eruption and may not be the cause of tooth eruption. One point of importance is that, the tissue beneath the growing root resists the apical movement of the developing root. This resistance results in the occlusal movement of the tooth crown as the root lengthens.

Mechanisms of Eruptive Tooth Movement 2. Bone Remodeling. Major proof is when a mand PM is removed without disturbing its follicle or you wire down the tooth germ, an eruptive pathway still forms within bone as osteoclasts widen the gubernacular canal. If the dental follicle is also removed no eruption path develops. So not sure if bone remodeling plays a significant role but is involved. One point to remember: Bone formation also occurs apical to the developing tooth Dental Follicle. Studies have shown that the reduced dental epithelium initiates a cascade of intercellular signals that recruit osteoclasts to the follicle. By providing a signal and chemoattractant for osteoclasts, it is possible that the dental follicle can initiate bone remodeling which goes with tooth eruption. Teeth eruption is delayed or absent in animal models and human diseases that cause a defect in osteoclast differentiation.

Mechanisms of Eruptive Tooth Movement 4. Periodontal ligament. Formation and renewal of PDL can be a factor in tooth eruption because of the traction power of the fibroblasts. However, presence of PDL does not always correlate with tooth eruption. Other factors involved are vascular pressures within the PDL. Examples of PDL being present but tooth not erupting and rootless teeth erupting have been reported.

Post Eruptive Tooth Movement 1. Movements to accommodate the growing jaws. Mostly occurs between 14 and 18 years by formation of new bone at the alveolar crest and base of socket to keep pace wit increasing height of jaws. 2. Movements to compensate for continued occlusal wear. Compensation primarily occurs by continuous deposition of cementum around the apex of the tooth. However, this deposition occurs only after tooth moves. Similar to eruptive tooth movement. 3. Movements to accommodate interproximal wear. Compensated by mesial or approximal drift. Mesial drift is the lateral bodily movement of teeth on both sides of the mouth. Very important in orthodontics.