Malocclusion Class ll:Distocclusion In this situation,the upper molars are placed not in the mesiobuccal groove but anteriorly to it. Usually the mesiobuccal cusp rests in between the first mandibular molars and second premolars. 190 Class II: Distocclusion In this situation, the upper molars are placed not in the mesiobuccal groove but anteriorly to it. Usually the mesiobuccal cusp rests in between the first mandibular molars and second premolars. Malocclusion