33. Functional appliances- Monoblock and Activator Flashcards
(21 cards)
Monoblock characteristics
- Tooth borne appliance(can be combined)
Monoblock elements
- Bi maxillary acrylic base
- Labial bow(0.8-0.9mm)
- Retention claps(0.7mm)
- Active springs and or expansion screws
Monoblock uses
- Maxillary prognathism-II
- Mandibular prognathism- III
- Symetrical bimaxillary compression
- Lateral deviation of mandible
- Deep and open bite
Monoblock working bite registration
- Sagittal plane-Mesial and distal/Class II/Class III
- Vertical plane
- Sagittal plane
- Mesial and distal occlusion recorded in class I/ In class II mandible protruded forward, in class III mandible retracted until edge to edge
- 1-2 mm bite opening between incisal edges of max and man teeth
- Midlines aligned
Monoblock acrylic base borders in maxilla
- Incisal egde of incisors and canines buccally
- Middle of occlusal surfaces of premolars and molars
- Distally-distal surface of molars
Monoblock acrylic base borders in mandible
- Lingual surfaces of mandibular anteriors-2-3 mm under cervices
- 5-6mm below mylohoid line in molars and premolars
Activator characteristics
- Tooth borne passive myotonic appliance
- Effective for class II=>
- Correction of muscle function
- Growth spurt utilisation
- Eruption guidance
Activator elements
- Labial bow (0.8-0.9mm)=>
- Anterior area for retention and/or tooth movement
- Retention clasps (0.7-0.8mm)=>
- Adams, circumferential clasps
- Supplemental elements=>
- Active springs, coil springs for headgear, expansion screws
- Acrylic base
circumferential clasp where molar tubes for headgear are present
Activator construction bite
- Sagittal plane=>maximal mandible protrusion then 3mm distally
- Vertical plane-=>bite opened between incisal edges of maxillary and mandibular anterior teeth- 4,8,10
- Sagittal plane-=>midlines aligned
Activator indications
- Class I open bite/deep bite
- Class II division 1 and 2
- Class III
- Laterognathia
- Post treatment retention
-Laterognathia-Central midline not aligned w/ facial midline at rest or in occlusion=>True cross bite
Activator contra-indications
- Class I problems w/ crowding
- Nasal stenosis
Nasal stenosis-narrowing of nasal cavity
Activator advantages
Little routine adjustments
Activator disadvantages
- Bulky
- Requires good patient co-operation
- No precise detailing of occlusion
Monoblock advantages
- Treats occlusal problems
- Changes muscle function
- Eliminates bad habits
- Acceptable wear time-14-16 hours
Difference between activator and monoblock
- Working wax bite
- Increased vertical opening
- Midlines aligned
- Greater length of lingual wings
Monoblock therapeutic principle
- Mandibular protraction to class I=>
- Moved mesially and condyle position changed
- Anterior interocclusal acrylic intrudes mandibular front teeth
- Posterior interocclusal acrylic discludes bite=>corrects deep overbite(vertical discrepancies)
- Acrylic grinded distally in maxilla and mesially in mandibe=>posterior teeth eruption guidance and bite opening
Monoblock therapeutic principle when expansion screw added
- Interocclusal acrylic transfers active force to posterior teeth=>
- Moved buccally
Monoblock time of use
At night and 2-3 hours during the day
Activator fabrication requirements
- Precise impression taking
- Lower impression tray extended manually to reach mylohoid line=>
- Where lower border of activator lies
Acrylic base of activator
- Extends to palate, interocclusal space between posterior teeth and then to lingual surfaces of mandiular anteriors
- In mandibular posterior area=>extends 12 mm apically to first molar gingival margin
- Mandibular anterior teeth area relieved with wax
Wax seperation to avoid acrylic lodging in area of mylohyoid line
Wax relief to present mandibular anterior teeth proclination
Activator time use
- Optimal time is during second premolar eruption phase=>peak of pubertal growth
- Worn at night(12-14 hours)
- Can be used w/facebow headgear
