A prospective study of lip adaptation during six months of simulated mandibular dental arch expansion.

The stability of dental arch expansion with conventional orthodontic treatments is disappointing. An increase in labial soft tissue pressure resulting from the expansion may contribute to this instability. An 8-month study of lip pressure changes resulting from lip bumper wear has been conducted, but no long-term studies have been conducted on pressure changes resulting from conventional expansion using fixed appliances. The purpose of the current study was to investigate changes in labial soft tissue pressures when conventional expansion was simulated. Twenty-two subjects wore a stent simulating mandibular dental arch expansion. They were instructed to wear the stent full-time. Lip pressure was recorded initially at 1 week, and monthly for 6 months. A repeated measures ANOVA was used for statistical analysis. A statistically significant (P < or = 0.05) increase in pressure was documented after initial insertion of the expansion-simulating stent. The increase was not maintained, suggesting an adaptation of the labial soft tissues.

Lip adaptation to simulated dental arch expansion. Part 1: Reliability and precision of two lip pressure measurement mechanisms.

Understanding the influence of lip and tongue pressure on tooth position requires a reliable method of measuring pressure. A transducer with a beam mechanism has been used extensively in the past. A transducer with a diaphragm mechanism has been recently introduced. Comparative in-vivo tests of these transducers have not been published. The purpose of this study was to investigate transducer reliability and precision. Transducers were placed intraorally in 22 subjects, and two lip pressure measurements were recorded. Paired t-tests and interclass correlations were used to evaluate repeatability and reliability. The error of the method was analyzed for each transducer type. Both transducer types produced measurements that were repeatable and reliable. The error was smaller for the diaphragm transducer. The diaphragm transducer is more precise.

Lip adaptation to simulated dental arch expansion. Part 2: One week of simulated expansion.

An increase in resting lip pressure and the resulting disruption of the intraoral pressure equilibrium may be responsible for the poor stability found with orthodontically expanded dentitions. Passive expansion strategies seek improved stability by altering lip pressure, thus creating a new equilibrium. One of these strategies has been shown to alter pressure favorably. However, pressure changes associated with conventional expansion need to be studied before conclusions regarding the superiority of passive expansion can be drawn. The purpose of this study was to examine lip pressure changes after 1 week of simulated conventional expansion. Twenty-two subjects agreed to wear a mandibular expansion-simulating stent full-time for 1 week. Resting pressure was measured in the midline and right canine areas. Midline lip pressure decreased significantly after 1 week. Resting pressure was measured in the midline and right canine areas. Midline lip pressure decreased significantly after 1 week while pressure in the canine area did not change significantly. This finding suggests an adaptive response that varies according to anatomic location.

Synthesis of some benzofuran and furocoumarin derivatives for possible biological activity.

Condensation of 5-formyl-6-methoxy-2,3-diphenylbenzofuran (I) and 6-formyl-5-methoxy-2,3-diphenylbenzofuran (II) with aliphatic or aromatic primary amines led to the formation of the corresponding anils (IIIa-k and IVa-c). The anils (IIIa,f,k or IVa-c) reacted with ethyl cyanoacetate, ethyl acetoacetate, or diethyl malonate to form the respective esters (Va-c or VIa-c). When Va-c or VIa-c were treated with pyridine hydrochloride, demethylation occurred followed by cyclization to form the corresponding furocoumarins (VIIa-c or VIIIa-c). Reduction of the anils using sodium borohydride furnished the corresponding Mannich bases (Xa-d and XI). The antimicrobial activity of compounds IIIi, IVc, Va, VIa, and VIIIa was investigated.