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Permissible limit for mandibular expansion /certified fixed orthodontic courses by Indian dental academy
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Permissible limit for mandibular expansion /certified fixed orthodontic courses by Indian dental academy

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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078

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  • 1. Permissible limit for mandibular expansion INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  • 2.  Mandibular expansion is brought about by lateral tipping of the molars.  Excessive expansion may result in excessive buccal tooth inclination which may disturb the occlusal relationship.  Inclination movement was used as a clinical index to determine the permissible limit of mandibular expansion.  Inclinations in occlusal surface of the first molar and intermolar width was measured before expansion, after expansion and before edgewise treatment. ABSTRACT www.indiandentalacademy.com
  • 3.  Average change in intermolar width was 5.42mm and the average angle of buccal tooth inclination was 10.16˚.  No significant correlation was found between age prior to treatment and treatment period when they were compared with intermolar width increments and inclination angles.  Significant positive correlation between retention duration and amount of expansion.  According to the study 1mm of expansion is accompanied by 5˚ of moalr lateral tipping.  The regression coefficient of the angle of buccal tooth inclination to the increment of the intermolar width was 0.2. www.indiandentalacademy.com
  • 4.  According to Hass,mandibular expansion is localised to the alveolar bone and is brought about by tooth inclination.  Adequate occlusal contact relationship provides normal stomatognathic functions.  The occlusal relationships are related to the mesiodistal and buccal-lingual tooth inclination.  Mandibular expansion can result in excessive tooth inclination and disturb normal occlusal functions. www.indiandentalacademy.com
  • 5.  Control -11 children -4 boys -7 girls -Angle’s class I malocclusion. -minimum crowding -no restorations covering the cusp tips.  Subjects 29 subject -10 males -19 females -age ranged from 6 yrs 10 months to 11 yrs 7 months. -With Angle’s class I malocclusion with posterior crossbite. -Some crowding in the lower arch. -No restorations covering the cusp tips. Subjects and methods www.indiandentalacademy.com
  • 6.  Appliance used in this study for expansion- Schwarz appliance www.indiandentalacademy.com
  • 7.  Reference plane –the lower occlusal plane including the midpoint of the tips of the right and left central incisors along the mesiobuccal cusp tips of the right and left first molars.  Occlusal surface of the molars was defined as a plane including the mesiobuccal ,mesiolingual and distobuccal cusp tip of the molars.  Angle of inclination-difference between the two angles. www.indiandentalacademy.com
  • 8.  The 3D measurements were made using a contact 3D measuring system.  All measurements were made ny one examiner to reduce intra examiner errors. www.indiandentalacademy.com
  • 9.  Statistical analysis  The data obtained were analysed using a statistical software package  Treatment changes pretreatment, post- treatment,and before start of edgewise treatment were measured in the treatment group and control group.  A index to estimate the permissible limit of mandibular expansion was obtained. www.indiandentalacademy.com
  • 10. Inference from the analysis  The increase in intermolar width with the expansion plate was 5.42mm  Mean molar inclination change-10.16˚during treatment.  Relapse was observed despite using a maintenance plate.  Molar width decreased to 4.12mm and molar inclination decreased to 8.26˚  Expansion at the beginning of edgewise treatment was 76% of the expansion achieved.  Longer retention period can maintain a greater amount of expansion. www.indiandentalacademy.com
  • 11.  Regression coefficient of the angle of buccal tooth inclination to the intermolar width increment =0.2  Permissible limit for mandibular expansion= =(θr+θl)×0.2 θr and θl are the angles of the occlusal surface of the first molars to the occlusal reference plane. www.indiandentalacademy.com
  • 12. An experimental study on mandibular expansion – increase in arch width and perimeter-Motoyosi et al, EJO 2002  Using 3D simulation the increase in arch width and perimeter was measured.  A space of 1.43mm opened between the canine and the first premolar with an increase in arch perimeter of 2.86mm.  The tip of the mesiolingual cusp moved 3.88mm laterally with an increase in intermolar width of 7.76mm.  A 1mm increase in arch width increased the arch perimeter by 0.37mm. www.indiandentalacademy.com
  • 13. Stability of transverse expansion in the mandibular arch AJO2003  An expanding lingual arch used for less than 6 months with the mandibular fixed edgewise appliance caused an increase in both the transverse and sagittal dimensions of the mandibular dental arch.  Transverse expansion was more stable in the posterior region of the mandibular dental arch than in the anterior region.  Mandibular intercanine width increase could be maintained only by fixed retention.  Although the maxillary and mandibular incisors were advanced and proclined, lip protrusion did not occur. www.indiandentalacademy.com
  • 14. Increase in arch perimeter due to orthodontic expansion. AJO 1991  Increase in midline arch width length by incisor advancement was four times more effective than molar expansion.  Combination of molar-canine expansion and canine incisor expansion yields results comparable to the total effect of expanding individual teeth. Combined molar canine expansion created increase in arch perimeter that was slightly less than those generated by incisor advancement alone. www.indiandentalacademy.com
  • 15. Treatment of Brodie bite by lower lateral expansion-a case reportJCPD1998  A brodie bite is a unilateral posterior scissor bite.  A patient 4 yrs 4 months was given a schwarz appliance to expand the lower arch.  The treatment duration was one year 2 months.  At the end of treatment the patient achieved good occlusion, muscle function and the function of the tmj improved. www.indiandentalacademy.com
  • 16. Modified mandibular Schwarz appliance-JCO 1998 Traditional schwarz appliance made patient co- operation difficult The clasps did not fit well in the undercuts. The pyramidal shape of the crowns produced an occlusal riding effect when the screw was activated. Provided exceptional overall retention. Reduces breakage. Maximum lingual extension to enhance alveolar expansion. www.indiandentalacademy.com
  • 17. www.indiandentalacademy.com For more details please visit www.indiandentalacademy.com
  • 18. The relationship of arch length to alterations in dental arch width- AJO2000 www.indiandentalacademy.com