Three-dimensional assessment of palatal area changes after posterior crossbite correction with tooth-borne and tooth bone–borne rapid maxillary expansion: A randomized controlled trial with 5-year follow-up

ObjectivesTo assess and compare the three-dimensional treatment changes in palatal surface area and volume using either tooth-borne (TB) or tooth bone–borne (TBB) rapid maxillary expanders and to evaluate the long-term effects of the two devices and the incidence of the relapse between the groups.Materials and MethodsA total of 52 consecutive patients who met the eligibility criteria were recruited and allocated to either the TB group, mean age 9.3 years (standard deviation [SD], 1.3), or the TBB group, mean age 9.5 years (SD, 1.2). Study casts were taken before, directly after, 1 year after, and 5 years after expansion. Study casts were digitized, superimposed, and evaluated. Participants were randomly allocated in blocks of different sizes using the concealed allocation principle in a 1:1 ratio.ResultsChanges in palatal volume, palatal surface area, and palatal projection area within and between the groups up to 5 years after expansion followed the same pattern and did not show any statistically significant differences between the groups. Relapse was seen in 15% of the patients. It seemed that open-bite and a Class III growth pattern could be assumed as prognosis-deteriorating factors in regard to stability of the treatment.ConclusionsThere were no significant differences between the TB and TBB groups in palatal volume, palatal shell area, or palatal projection area directly after expansion or at 1 year and 5 years after expansion, which implies that the two devices gave rise to the same immediate and long-term outcomes.     

Lactate dehydrogenase isoenzymes of the human periodontal ligament

The isoenzymes of lactate dehydrogenase (E. C. 1. 1. 1. 27.) from the periodontal ligament on the root surface of extracted erupted permanent human teeth have been separated and quantitated by means of cellulose acetate membrane electrophoresis.
LDH-3 and LDH-4 were the predominating isoenzymes. and smaller amounts of LDH-2 and LDH-5 were also present. Only traces of LDH-1 could be seen. The results indicate the presence of both aerobic and anaerobic metabolic pathways in the human periodontal ligament.
These pathways bring about an efficient, economical energy production under normal circumstances, and make the survival of this tissue possible under hypoxic conditions, when the blood supply is briefly interrupted. The results further show that determinations of the survival time of the periodontal ligament on a tooth outside its alveolus have to be made by activity measurements of both aerobic and anaerobic enzymes.