Experimental forward mandibular displacement in sheep

Trabecular anisotropy and collagen fibre orientation in the mandibular condyle following experimental functional appliance treatment using sheep

“…Thed etailede xperimentalp rocedure has been reportede lsewhere (22). In brief,a totalo fe ight, four-month-old,c astrated male Australian Merino sheep from the sameflockwererandomlyassignedequally into experimentala nd control groups.E xperimentala nimalsr eceivedf unctionala ppliances thatw erea nalogous (22) to the Clark Tw in Block whichiscommonlyused to treat human mandibular deficiency.Ineffect,the appliances were cast metalsplints cementedt ot he maxillarya nd mandibular teeth such thatt he guide planesd eflected the mandible forwarda st he sheep triedt o chew.T heyw ered esignedt od isplace the mandible forwardb yf our mm.O therwise, alla nimalsw erem anaged in the same manner.Another four sheep from the same flockwereinitiallyassignedtoathirdgroup wearing an appliance without forwardd isplacemento ft he mandible. Twos heep in this group died from reasons other than wearing the appliances.…”

“…Because differences between the left and right sideso ft he condyle were not previouslyfound for anyvariable (21)(22)(23), the data from both sideswerepooled for analysisproviding eight condyles in each group. Our previous results demonstratedi ncreased mandibularc ondylar length in responsetoexperimentalfunctionalappliance intervention to asimilardegreereported for human studies (16).…”

“…The mandibularcondyle is agrowthsite within the TMJb ut currentk nowledge of the responses of the mandibular condylar tissuet of unctionala ppliances comes mainlyfrom animalexperiments.Inorderto mimic orthodontic treatment procedures, specific functional appliances have been used to promptthe mandible to aprotrusive position in various animals pecies (9,22,26). The overallr esults of the subsequent bone adaptation have showni ncreased bone-forming activity of the mandibular condylar tissue.…”

Possíveis efeitos do aparelho propulsor mandibular sobre o crescimento da mandíbula e tipos de fibras nos músculos mastigatórios.

“…A base do crânio, maxila, mandíbula e ATM são anatomicamente similares e as características funcionais do sistema estomatognático, também são semelhantes (ISAACSON et al, 1990 O carneiro foi proposto como um modelo animal alternativo para pesquisas sobre o crescimento facial (PRINCE et al, 1997;MA et al, 2002) e cirurgia bucomaxilofacial (KARAHARJU-SUVANTO et al, 1990. Apesar das diferenças funcionais, as ATMs de carneiros e humanos são similares quanto ao tamanho e à anatomia (BOSANQUET e GROSS, 1987).…”

“…Entretanto, apesar das semelhanças, existem diferenças funcionais e anatômicas do sistema estomatognático que precisam ser levadas em conta. Carneiros possuem o arco superior significativamente mais largo que o inferior, de modo que não é possível o contato oclusal em ambos os lados simultaneamente; não possuem incisivos superiores e há um espaço edentado de 9 cm entre a região dos incisivos inferiores e os molares (MA et al, 2002). Os movimentos mandibulares são primariamente médio-laterais, possibilitando ao animal triturar, moer os alimentos e quebrar as fibras de celulose para que possam ser digeridas (DOVITCH e HERZBERG, 1968).…”