The effect of occlusal forces on the periodontium is influenced by what 4 things?
How does periodontium respond to magnitude?
1. widening of the periodontal ligament space
2. increase in number and width of periodontal ligament fibers
3. increase in density of alveolar bone
How does the periodontium respond to change in direction of occlusal forces?
principle fibers of the periodontal ligament are arranged so that they best accommodate occlusal forces along the long axis of the tooth
Which directions of occlusal force are most likely to injure the periodontium?
What is the definition of "trauma from occlusion"?
tissue injury resulting from occlusal forces that exceed the adaptive capacity of the tissue-used in connection with injury to periodontium-not symptoms
What are some symptoms of excessive occlusal forces?
(these are not "trauma from occlusion"-which connotes injury to periodontium)
Discuss acute trauma from occlusion.
acute trauma can cause pain, sensitivity to percussion, mobility
these can dissipate by shift in tooth position or tooth wear of correction of problem as injury will heal
otherwise injury worsens and necrosis, periodontal access,
also "cementum tears" can result
Discuss chronic trauma from occlusion.
More common than acute and of greater clinical significance.
Most often from gradual changesin occlusion produced by tooth wear, drifting, extrusion, parafuncional habits and not sequelae to acute perio trauma
What is the criterion that determines if an occlusion is traumatic?
if it produces periodontal injury-
may occur when occlusion appears normal, not all malocclusions are traumatic
what are some other terms associated with traumatic occlusion?
What is primary occlusal trauma
caused by alteration in occlusal forces
What is secondary occlusal trauma?
caused by reduced capacity of periodontium to withstand occlusal forces
What are some examples of primary occlusal trauma?
prosthetic replacement creates excess force on abutment or antagonistic teeth
drifting or extrusion
Changes produced by primary trauma do not alter what periodontal tissue? why is this probably true?
level of connective tissue attachment and do not initiate pocket formation
Probably because supracrectal gingival fibers are not affected and therefore prevent apical migration of junctional epithelium
Explain how secondary trauma from occlusion occurs.when
Marginal inflammation>bone loss>reduced periodontal ligament attachment area>change in leverage on remaining tissues>periodontium becomes vulnerable to injury>previously tolerated occlusal forces become traumatic
What are the 3 situations on which excessive occlusal forces can be superimposed?
-Normal periodontium and normal bone height=(primary trauma from occlusion) -Normal periodontium and reduced bone height=(secondary trauma from occlusion) -Marginal periodontitis and reduced bone height=(secondary trauma from occlusion)
(see figure 29-3)
What is a theoretical mechanism found in experimental animals that could result in secondary trauma from occlusion?
systemic disorders can reduce tissue resistance and previously tolerated occlusion can become excessive
Tissue response to increased occlusal forces occurs in what three stages?
Discuss what happens in the first phase, injury phase of tissue response to increased occlusal forces?
If the force is chronic, periodontium is remodeled to cushion the impact. The ligament is widened at the expense of bone resulting in angular bone defects without periodontal pockets and the tooth becomes loose
What are the areas of periodontium most susceptable to injury from excessive occlusal forces?
Injury to periodontium from excessive occlusal forces causes a temporary depression (return to normal after dissipation of forces) in what?
-mitotic activity and rate of proliferation and differentiation of fibroblasts -collagen formation -bone formation
Discuss the second phase, repair phase of tissue response to excessive occlusal forces.
Constant repair is normal, traumatic occlusion stimulates increased activity Damaged tissues are removed, new connective tissue, bone, cementum formed
forces remain traumatic only as long as damage produced exceeds reparative capacity of tissue
Discuss stage 3, the adaptive remodeling of tissue in response to excessive occlusal forces.
occurs when the repair phase cannot keep pace with destruction periodontium is remodeled -thickened periodontal ligament which is funnel shaped at the crest, angular defects in bone, no pocket formation, involved teeth become loose
Histiometrically, the injury phase shows increased areas of resorption and ____________, the repair phase shows decreased resorption and __________.
-decreased bone formation -increased bone formation
What are the effects of insufficient occlusal forces? What situations can cause it?
insufficient stimulation causes thinning of periodontal ligament atrophy of fibers osteoperosis of bone reduction in bone height
hypofunction from open bite, lack of antagonistic tooth, unilateral chewing
What affects reversibility of traumatic lesions?
injurious force must be relieved
presence of inflammation as result of plaque accumulation may affect it
What is the effect of occlusal forces on dental pulp?
not established in animals pulpal reactions noted unless force is minimal or occured over short periods-no pulpal reaction
How does trauma from occlusion in humans differ from trauma from occlusion in animal experimental models?
Occlusal forces act alternitively in opposing directions as opposed to a continuous or intermittent force in one direction
Studies performed attempting to determine mechanisms by which trauma from occlusion affects periodontal disease showed what?
none of the experimental methods caused gingival inflammation or pocket formation but did show different degrees of functional adaptation to increased forces
Why is the marginal gingiva unaffected by trauma from occlusion?
Its blood supply is not affected even when the vessels of the periodontal ligament are obliterated by excessive occlusal forces It was bacterial plaque accuulation that initiated gingivitis and resulted in pp formation and affected marginal gingiva - trauma from occlusion occurs in supporting tissues and not in the gingiva
Define the "zone of co-destruction" as described by Glickman
As long as inflammation if confined to gingiva the inflammatory process is not affected by occlusal forces. when inflammation extends into supporting periodontal tissues (gingivitis becomes periodontitis) plaque induced inflammation enters the zone influenced by occlusion
When trauma from occlusion is eliminated reversal of bone loss occurs except in the presence of periodontitis. What does this indicate and how is this used clinically?
indicates inflammation inhibits the potential for bone regeneration
It is important to eliminate marginal inflammatory component in cases of trauma form occlusion because the presence of inflammation affects bone regeneration after the removal of the traumatizing contacts
Trauma from occlusion changes the shape of the alveolar crest. Describe this.
widening of the marginal periodontal ligament space, narrowing of the interproximal alveolar bone, shelf-like thickening of the alveolar margin therefore trauma from occlusion changes the architecture of the area around the inflamed site (though the trauma does not influence inflammation)
There are 5 theories to explain absence of inflammation vs presence of inflammation and response to trauma from occlusion. What are they? no's 2 thru 5
2-altered pathway of extension of gingival inflammation to underlying tissues -it goes to periodontal ligament instead of bone and resulting bone loss is angular -pockets become infrabony 3-trauma induced areas are favorable for plaque and calculus may cause deeper lesions 4-supragigngival plaque becomes subgingival as tooth is tilted -favorable for infrabony pocket 5-loose teeth have a pumping effect on plaque metabolites increasing their diffusion
There are 5 theories to explain absence of inflammation vs presence of inflammation and response to trauma from occlusion. What are they? no 1
1-absence of inflammation==response to trauma from occlusion is limited to adaptation to the increased forces presence of inflammation==changes in shape of alveolar crest may be conducive to angular bone loss and existing pockets may become infrabony
What are the clinical signs of trauma from occlusion alone?
increased tooth mobility-most common(cannot be considered pathologic-an adaptation and not a disease process)
What are the possible radiographic signs of trauma from occlusion alone?
1- Widened periodontal space often with thickening of lamina dura along lateral root aspect, apical region, and bifurcation areas(not pathologic- an adaptation) 2- Vertical rather than horizontal destruction of interdental areas 3-Radiolucency and condensation of alveolar bone 4-Root restoption
define pathologic tooth migration
tooth displacement that occurs when the balance of factors that maintain physiologic tooth position are disturbed by periodontal disease and tooth movement results-common and can be an early sign of disease
what is pathologic migration along the occlusal or incisal direction called
What two major factors play a roll in maintaining normal position of teeth? how does this relate to pathologic migration?
1-health and normal height of periodontium 2-forces exerted on teeth (forces of occlusion, lips, cheeks, tongue) thus path. migr. occurs under conditions that weaken the periodontal support,increase or modify forces exerted on teeth, or both
What are the 6 factors that are important when related to forces of occlusion?
1-tooth morphologic features and and cuspal inclination 2-presence of full complement of teeth 3-physiologic tendency toward mesial migration 4-nature and location of contact point relationships 5-proximal, incisal, occlusal attrition 6-axial inclination of teeth
Discuss weakened periodontal support in relation to pathologic migration of teeth
forces that are acceptable to an intact periodontium become injurious when periodontal support is reduced. as position changes tooth is subjected to abnormal occlusal forces which aggravate the periodontal destruction and tooth migration migration may continue after tooth no longer contacts its antagonist-tongue, food bolus, proliferating granulation tissue may provide the force is also an early sign of "localized aggressive periodontitis"
How do changes in forces exerted on teeth induce pathologic migration of teeth?
unreplaced missing teeth, failure to replace first molars, trauma from occlusion, pressure from tongue, pressure from granulation tissue
Discuss "slightly excessive pressure" vs "slightly excessive tension.
excess pressure=resorption of alveolar bone, widened periodontal ligament space results, blood vessels are numerous and reduced in size
excess tension= elongation of PDL fibers and apposition of alveolar bone, blood vessels are enlarged.
Define "undermining resorption"
pressure is severe enough to force root against bone, necrosis of PDL and bone, bone is resorbed from viable PDL adjacent to necrotic areas and from marrow spaces
Define buttressing bone
Bone is resorbed by excessive occlusal forces and the body attempts to reinforce the thinned bony trabeculae with new bone it is an important feature of the reparative process also occurs when bone is destroyed by inflammation or osteolytic tumors
When buttressing bone occurs within the jaw it is termed what? when it occurs on the bone surface it is called what?
central buttressing peripheral buttressing
what is lipping?
peripheral buttressing produces a shelf-like thickening of the alveolar margin
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