Evaluation of Swallowing Function in Relation to Oropharyngeal Dysphagia in Patients with Operated Unilateral Cleft Lip and Palate

OBJECTIVE

To determine the occurrence of oropharyngeal dysphagia (OD) signs and symptoms in patients with operated unilateral cleft lip and palate (CLP).

MATERIALS AND METHODS

This prospective study was conducted on 15 adolescents with operated unilateral CLP (CLP group) and 15 non-cleft volunteers (control group). Initially, the Eating Assessment Tool-10 (EAT-10) questionnaire was administered to subjects. OD signs and symptoms such as coughing, the sensation of choking, globus sensation, the need to clear the throat, nasal regurgitation, difficulties of bolus control multiple swallowing were evaluated by patient complaints and physical examination of swallowing function. Also, the Functional Outcome Swallowing Scale was used to determine the severity of the OD. Fiberoptic endoscopic evaluation of swallowing (FEES) with water, yogurt, and crackers was performed.

RESULTS

The prevalence of OD signs and symptoms based on patient complaints and physical examination of swallowing was low (range, 6.7 to 26.7%), and nonsignificant differences were observed between the groups for these parameters as well as for EAT-10 scores. According to the Functional Outcome Swallowing Scale findings, 11 of 15 patients with CLP were asymptomatic. Fiberoptic endoscopic evaluation of swallowing indicated that post-swallow pharyngeal wall residues with yogurt were significant in the CLP group with a prevalence of 53% ( P < 0.05), whereas differences between the groups in terms of cracker and water residues were nonsignificant ( P > 0.05).

CONCLUSION

OD in patients with repaired CLP was manifested mainly in the form of pharyngeal residue. However, it did not appear to cause significant increases in patient complaints compared with healthy individuals.

Evaluation of swallowing in transverse maxillary deficiency patients before and after rapid maxillary expansion

OBJECTIVES

To evaluate swallowing function in relation to oropharyngeal dysphagia (OD) in adolescents who had transverse maxillary deficiency with posterior crossbite and high-arched palate, before, and after rapid maxillary expansion (RME).

MATERIALS AND METHODS

Twenty patients (mean age: 13.0 ± 3.1) with bilateral posterior crossbite and high-arched palate (RME group: RMEG) and 20 volunteers (mean age: 13.4 ± 2.6) with Class I crowding without posterior crossbite or high-arched palate (control group: CG) were recruited. OD signs and symptoms were evaluated using the Eating Assessment Tool-10 (EAT-10) questionnaire, patient complaints, and physical examination of swallowing function before (T1) and 7 months after (T2) RME. Additionally, fiberoptic endoscopic evaluation of swallowing (FEES) with water, yogurt, and cracker was performed. In CG, evaluation of swallowing was performed only once, corresponding to T1 of RMEG.

RESULTS

Prevalence of OD signs and symptoms based on patient complaints and physical examination of swallowing was low (5%-15%), and nonsignificant differences were observed between CG and RMEG at T1 for these parameters as well as for EAT-10 scores. Total post-swallow pharyngeal residue with yogurt was significantly different between CG and RMEG at T1, with a prevalence of 60% in RMEG (P < .05). There was no significant difference regarding residue with yogurt between T1 and T2 in RMEG (P > .05).

CONCLUSION

Patients with a maxillary transverse deficiency were affected by pharyngeal residue as indicated by FEES, but it did not appear to improve in short-term follow-up in patients treated with RME.

Comparison of 2 different wear protocols of vacuum-formed retainers with respect to the conventional parameters and 3-dimensional superimpositional analysis

INTRODUCTION

This study aimed to compare the effectiveness of 2 different wear protocols of vacuum-formed retainers (VFR) in terms of angular and linear displacement of teeth using 3-dimensional (3D) superimpositional analysis and conventional model parameters.

METHODS

The study was conducted on 2 groups, each consisting of 17 patients randomly assigned to the part-time group or full-time group of VFR wearing after a nonextraction treatment. While conventional model measurements were assessed on 3D dental casts, 3D tooth movements were evaluated by digitally superimposed scans of casts acquired at 4-time points (debonding and 1, 3, and 6 months after debonding). Regarding conventional parameters, the difference between time-dependent changes among the groups was tested using the nonparametric Brunner-Langer and parametric linear mixed models. Considering 3D measurements, comparisons of groups were made using the Student t tests.

RESULTS

There were no significant intergroup differences regarding conventional model parameters at any time (P >0.05). Significant intergroup differences were observed regarding angular and linear relapses in the labiolingual direction for maxillary and mandibular incisors, as well as the rotational relapses for maxillary left canine and mandibular right lateral incisor, which were greater in the part-time group in the first month and at the end of 6 months (P <0.05).

CONCLUSIONS

Conventional model parameters appear to play a debatable role in evaluating the effectiveness of a retainer wear regimen. Three-dimensional analysis of tooth movements revealed that part-time VFR wear was less effective in retaining labiolingual and rotational tooth movements for the first month after debonding.

Three-dimensional digital evaluation of tooth symmetry and volume in patients with missing and peg-shaped maxillary lateral incisors

INTRODUCTION

This study aimed to evaluate the 3-dimensional tooth crown symmetry and the crown volumes of maxillary and mandibular teeth in patients with unilateral or bilateral missing or peg-shaped maxillary lateral incisors.

METHODS

Six groups were established for the possible clinical variations in patients with unilateral missing or peg-shaped maxillary lateral incisors, bilateral presence of these tooth anomalies, and a control group (CG) with normal lateral incisors. The study was conducted on digital dental models of 132 patients. The morphologic symmetry of the antimere teeth was investigated using 3-dimensional deviation analysis. Volumes of contralateral teeth were compared within and among groups for the maxilla and mandible. Furthermore, volumes of teeth were compared in missing and peg-shaped quadrants and quadrants of CG. Intergroup differences were tested using one-way analysis of variance and Kruskal-Wallis tests, whereas paired t and Wilcoxon tests were used for parametric and nonparametric variables, respectively, for intragroup comparisons.

RESULTS

Significant deviations in symmetry of antimere teeth were not detected (P >0.05). The volumes of mandibular central and lateral incisors in missing or peg-shaped lateral incisor groups were smaller than in the CG (P <0.05). Per quadrant analysis, volumes of the maxillary central incisor and mandibular central incisors, canines, and first molars in quadrants with missing or peg-shaped lateral incisors were smaller than in the control quadrants (P <0.05).

CONCLUSIONS

Neither unilateral nor bilateral presence of missing or peg-shaped maxillary lateral incisors affected the morphologic symmetry of antimere teeth but did affect tooth volume, especially in the mandibular arch.

Bond strength of metal brackets to feldspathic ceramic treated with different surface conditioning methods: an in vitro study

Purpose:

To compare MEP which is originally manufactured for increasing bond strength between organic resins and ceramic with conventional surface treatment methods in preparation of leucite-reinforced FC surfaces regarding shear bond strength (SBS) of stainless steel brackets and the mode of bond failure.

Materials and methods:

Forty specimens that were fabricated from FC material and glazed were randomly assigned to four surface conditioning methods: (1) CoJet Sand; (2) MEP; (3) HF acid etching followed by silane coupling agent; (4) Diamond bur followed by silane coupling agent. The SBS was determined using universal testing machine. Bond failure sites were classified according to Adhesive Remnant Index (ARI).

Results:

No statistically significant difference (p less than 0.05) was found in SBS between the groups while significant intergroup differences were detected concerning ARI scores (p less than 0.001). Group 1 had ARI score 1 and 2 indicating mode of failure at the adhesive interface with greater percentage of the adhesive left on bracket base. The other groups had higher frequency of ARI score 3 and 2. The quantity of the ARI retained on the ceramic surface was highest in Group 3, followed by Group 4 and Group 2.

Conclusion:

MEP can be a suitable alternative for bonding metal brackets to FC surface.

Root resorption due to orthodontic treatment using self-ligating and conventional brackets : A cone-beam computed tomography study

OBJECTIVES

Purpose of the present study was to compare external root resorption (ERR) volumetrically in maxillary incisors induced by orthodontic treatment using self-ligating brackets (Damon Q, DQ) or conventional brackets (Titanium Orthos, TO) with the help of cone-beam computed tomography (CBCT).

PATIENTS AND METHODS

A sample of 32 subjects, with Angle Class I malocclusion and anterior crowding of 4-10 mm, was divided randomly into two groups: a DQ group, in which self-ligating DQ brackets with Damon archwires were used; and a TO group, in which conventional TO brackets with large Orthos archwires were applied. The study was conducted using CBCT scans taken before (T1), and near the end (9 months after the initiation of treatment; T2) of the orthodontic treatment. The extent of ERR was determined volumetrically using Mimics software. Changes in root volume were evaluated by repeated-measures analysis of variance as well as by paired and independent t-tests.

RESULTS

While significant differences were found between T1 and T2 for root volume in both groups (p < 0.05), there was no difference between the groups regarding the amount (mm³ or relative change) of ERR (p > 0.05). Maxillary central and lateral incisors showed similar volume loss (p > 0.05). Furthermore, the TO group showed a higher prevalence of palatinal and proximal slanted RR compared with the DQ group (p < 0.05).

CONCLUSIONS

It is not possible to suggest superiority of one bracket system over the other only considering root resorption pattern or amount. Higher incidence of slanted RR found in patients treated with the TO system warrants further research to identify possible specific causes.

Modifications in Presurgical Nasoalveolar Molding Treatment of Bilateral Cleft Lip and Palate Patients With Severely Malpositioned Premaxillae

OBJECTIVE

The aim of this study was to evaluate a modified presurgical nasoalveolar molding (PNAM) treatment for patients with bilateral cleft lip and palate (BCLP) with severely malpositioned premaxillae.

SETTING

This study was conducted at the Faculty of Dentistry, Department of Orthodontics, Ege University, Bornova, Izmir, Turkey.

METHOD

Retention arms were manufactured using a mold that we developed, and prefabricated retraction apparatuses were applied to the plaster model obtained from the patient. During the acrylic curing process, the flanges of the appliances were elongated into the sulcus without including the premaxilla. The premaxilla was aligned with the midline with an elastic band system, and the lip hanger was constructed with 0.023-in stainless steel wire. Elastic bands were stretched between the retraction apparatuses and the lip hanger based on the desired force. Nasal stents were added to the retention arms when the cleft width was reduced to less than 6 mm.

CONCLUSION

The modified PNAM treatment enabled faster derotation of the premaxilla and earlier initiation of retraction. The prefabricated retraction apparatus and retention arm provided efficient PNAM for patients with BCLP.

The effects of maxillary expansion on the soft tissue facial profile

Purpose

The aims of this retrospective study were to evaluate the possible changes in soft tissue facial profile induced by orthopedic rapid maxillary expansion (RME) and surgically assisted rapid maxillary expansion (SARME), and to correlate them with the underlying hard tissue alterations.

Materials and Methods

16 patients who received bone borne SARME and 25 patients who were subjected to RME using metal cast splint hyrax appliance were analyzed retrospectively. This research was conducted on lateral cephalometric radiographs taken on 2 occasions: before expansion (T1) and at the beginning of any further orthodontic treatment (T2). Investigated lateral cephalometric parameters consisted of Holdaway soft tissue measurements with some supplementary soft tissue, skeletal and dental assessments.

Results

The acquisition of T2 cephalograms which conforms to the initiation of further orthodontic treatment corresponded to 83.25±3.51 days for SARME and 85.68±4.37 days for RME after the expansion was completed. The only significant change in soft tissue profile of the SARME group was a decrease in upper lip thickness (p<0.05), whereas in the RME group, decrease in soft tissue facial profile angle and increase in H angle were found to be statistically significant (p<0.05 for each). For the RME group, the changes in soft tissue facial profile angle and H angle correlated only with the changes in SNB angle (p<0.05).

Conclusion

While bone-borne SARME did not seem to possess the potential to alter soft tissue profile, tooth-borne RME caused a more convex soft tissue profile related to a reduction in SNB.

Evaluation of mandibular hard and soft tissues in cleft patients

Purpose:

The aim of this study was to compare the mandibular hard and soft tissue measurements of unilateral and bilateral cleft lip and palate patients with non-cleft individuals.

Materials and Methods:

The study sample comprised of lateral cephalograms of 45 subjects. Sample included 15 non-cleft (NC), 15 unilateral cleft lip and palate (UCLP) and 15 bilateral cleft lip and palate (BCLP) cases whose age were between 15 to 17. 1 angular 13 linear measurements were carried out using Arnett and Gunson soft tissue cephalometric analysis and 4 angular measurements were calculated with Steiner Analysis.

Results:

Mandibular incisor inclinations relative to the occlusal plane (Md1-Md OP) were significantly greater and mandibular incisor projections (Md1-TVL) were significantly retrusive in cleft subjects (p<0.05). Projection values pertaining to lower lip anterior (LLA-TVL), soft tissue B point (B’-TVL), and soft tissue pogonion (Pog’-TVL) were significantly deficient as well in cleft patients (p<0.05). Sagittal position of the maxilla (SNA) (p<0.001) and intermaxillary relation of the jaws (ANB) were significantly deficient in UCLP subjects (p<0.05) and BCLP individuals (p<0.01). LLA-TVL and B’-TVL correlated with SNB in cleft patients (p<0.05).

Conclusion:

Decreased lower lip and chin projection values suggest that mandibular region of cleft patients should be taken into account in forming the treatment plan to improve the esthetic outcome of orthodontic and plastic surgery interventions.

Comparative Evaluation of the Pharyngeal Airways and Related Soft Tissues of Unilateral and Bilateral Cleft Lip and Palate Patients with the Noncleft Individuals

Aim

This study is a comparison of pharyngeal airways and associated soft tissues of unilateral and bilateral cleft lip and palate patients with the noncleft individuals.

Materials and Methods

Twenty-four unilateral cleft lip and palate patients (UCLP), 21 bilateral cleft lip and palate patients (BCLP), and 26 noncleft patients (NC) between ages 15 to 17 were included in the study. Eleven linear, 1 angular, and 1 proportional measurements were carried out on pretreatment lateral cephalometric head films of these individuals.

Results

The nasopharyngeal depths were markedly reduced in BCLP when compared with the NC (P < .001) and UCLP (P < .01) with a significant difference (P < .01) also among UCLP and NC. Minimum space behind the tongue concerning BCLP and UCLP were significantly lower compared to the NC (P < .001 and P < .01, respectively). In pairwise comparison among the clefts, BCLP showed significant (P < .05) narrowing of this distance. Tongue heights and velar lengths were significantly (P < .001) lower in cleft groups compared to the controls. Similarly, the hyoid bone was positioned in a significantly (P < .01) anterior and inferior direction in cleft patients. Comparison of the mean ratio of velar length to nasopharyngeal depth of the three groups revealed significant (P < .001) inadequacies in cleft patients with significantly (P < .05) more severely reduced values in BCLP.

Conclusion

Pharyngeal airways and involved soft tissues of cleft patients show serious inadequacies compared to controls, with significant diversities among cleft types pertaining to some of the parameters investigated. It should be kept in mind that these variations can influence function in terms of respiration and phonation.

Class II subdivision treatment with the Forsus Fatigue Resistant Device vs intermaxillary elastics

OBJECTIVE

To compare the effectiveness of comprehensive fixed appliance treatments implemented in combination with Forsus or intermaxillary elastics in Class II subdivision subjects.

MATERIALS AND METHODS

Twenty-eight Class II subdivision patients were allocated to two groups using matched randomization: Forsus group (mean age, 14.19 ± 1.02 years) and elastics group (mean age, 13.75 ± 1.16 years). Patients received fixed appliance therapy in combination with either Forsus or intermaxillary elastics. The study was conducted on lateral cephalograms and digital models acquired before orthodontic treatment and 10-12 weeks after the fixed appliances were removed.

RESULTS

The treatment phase comprising the use of Forsus (4.53 ± 0.91 months) was significantly shorter compared with elastics application (6.85 ± 1.08 months). This was also true for comparing duration of overall comprehensive treatment in both groups. Extrusion and palatal tipping of maxillary incisors and clockwise rotation of the occlusal plane were greater in the elastics group (P < .05). The mandibular incisors were proclined in both groups (P < .001), but no significant difference was observed between groups (P > .05). The mandibular incisors showed intrusion in the Forsus group and extrusion in the elastics group; the difference between groups was significant (P < .05). Overbite was decreased in both groups (P < .001) in similar amounts. Improvement in overjet, mandibular midline deviation, and correction of molar relationship on the Class II side were greater in the Forsus group (P < .05).

CONCLUSION

Forsus is more effective for correcting Class II subdivision malocclusion in a shorter treatment period with minimal patient compliance required.

Comparison of anterior and posterior mini-implant-assisted maxillary incisor intrusion: Root resorption and treatment efficiency

OBJECTIVE

To compare, through cone-beam computed tomography (CBCT), the root resorption and treatment efficiency of two different mini-implant-assisted modalities in intruding the maxillary incisors.

MATERIALS AND METHODS

Thirty-two adults who had deep bite and elongated maxillary incisors were randomly allocated to two groups: anterior mini-implant group (AMG) and posterior mini-implant group (PMG). In the AMG, approximately 40 g of force was applied per side with elastic chains from mini-implants placed between the lateral incisors and canines and in the PMG, with beta-titanium wires from mini-implants placed between the second premolars and first molars. This study was conducted on CBCT scans taken before intrusion and after 4 months of intrusion. Data were analyzed by means of a paired t-test, independent t-test, and Pearson's correlation test.

RESULTS

One patient was excluded from the AMG due to mini-implant loosening. While the incisors showed a significant reduction in length and volume, this amount was greater in the AMG, especially in the central incisors (P < .05). Together with the mean intrusion rates of 0.62 and 0.39 mm/mo in the AMG and PMG respectively, the center of resistance of the incisors showed distal movement with labial tipping; these changes were greater in the PMG (P < .001). Volumetric root resorption was correlated with the amount of intrusion (P < .05).

CONCLUSIONS

Intrusion anchoring from posterior mini-implants is preferred in cases of upright incisors, as the use of such mechanics directs the roots into the spongiosa where they undergo less root resorption and more labial tipping.

Comparison of stepwise vs single-step advancement with the Functional Mandibular Advancer in Class II division 1 treatment

OBJECTIVE

To compare two groups of subjects at the peak of the pubertal growth period treated with the Functional Mandibular Advancer (FMA; Forestadent, Pforzheim, Germany) appliance using either single-step or stepwise mandibular advancement.

MATERIALS AND METHODS

This study was conducted on 34 Class II division 1 malocclusion subjects at or just before the peak phase of pubertal growth as assessed by hand-wrist radiographs. Subjects were assigned to two groups of mandibular advancement, using matched randomization. Both groups were treated with the FMA. While the mandible was advanced to a super Class I molar relation in the single-step advancement group (SSG), patients in the stepwise mandibular advancement group (SWG) had a 4-mm initial bite advancement and subsequent 2-mm advancements at bimonthly intervals. The material consisted of lateral cephalograms taken before treatment and after 10 months of FMA treatment. Data were analyzed by means paired t-tests and an independent t-test.

RESULTS

There were statistically significant changes in SNB, Pg horizontal, ANB, Co-Gn, and Co-Go measurements in both groups (P < .001); these changes were greater in the SWG with the exception of Co-Go (P < .05). While significant differences were found in U1-SN, IMPA, L6 horizontal, overjet, and overbite appraisals in each group (P < .001), these changes were comparable (P > .05).

CONCLUSION

Because of the higher rates of sagittal mandibular skeletal changes, FMA using stepwise advancement of the mandible might be the appliance of choice for treating Class II division 1 malocclusions.

Nasopharyngeal Airway Volume for Different GOSLON Scores in Patients with Unilateral Cleft Lip and Palate

Objective

The aim of this study is to evaluate the nasopharyngeal airway volumes of patients with unilateral cleft lip and palate (UCLP) with different GOSLON scores.

Methods

The study sample consisted of 34 patients with UCLP and 20 controls with no cleft history. In the UCLP group, three experienced examiners used the GOSLON Yardstick to rate dental arch relationships, and the sample was divided into three groups as GOSLON 2 (G2) (n = 13), GOSLON 3 (G3) (n = 10), and GOSLON 4 (G4) (n = 11). Airway volumes were constructed using three-dimensional computed tomography data and divided into four compartments named the nasal airway, and superior, middle, and inferior pharyngeal airways.

Results

No statistically significant difference was detected among G2, G3, and G4 between the constitutive airway departments of the nasopharyngeal region. However, nasal airway volumes were significantly higher in the control group when compared with the UCLP group.

Discussion

Although there was no correlation among the investigated parameters, it is also a fact that airway capacities display a great variability among patients when investigated three dimensionally.

Conclusion

Although the severity of GOSLON scores might predetermine the extent of which the airways are affected from the cleft, a larger sample size is needed in future studies.

Influence of lateral cephalometric radiographs on extraction decision in skeletal class I patients

BACKGROUND

Radiographic examination is considered 'justified' only when detection of a condition that would change the mechanisms and timing of treatment is possible. Radiographic safety guidelines have restricted the indication of lateral cephalometric radiographs (LCRs) to presence of distinct skeletal Class II or Class III. However, they are taken routinely in clinical practice and considered to be part of the 'gold' standard for orthodontic diagnosis. Therefore, the aim of this study was to test the null hypothesis that lateral cephalometric radiograph (LCR) evaluation would not alter the extraction/non-extraction decision in orthodontic treatment planning of skeletal Class I patients.

MATERIALS AND METHODS

Intraoral and extraoral photographs, dental casts and extraoral radiographs of 60 skeletal Class I patients were prepared digitally for assessment using a presentation software. One experienced (EO) and inexperienced orthodontist (IO) was asked to decide on extraction or non-extraction on a Likert-type linear scale for treatment planning. This procedure was repeated 4 weeks later with a mixed order of patients and the LCRs being omitted. Kappa, Weighted Kappa (WK) and McNemar scores were computed to test decision consistency and Bland-Altman plots together with 95% limits of agreement were used to determine measurement accuracy and presence of systematic bias.

RESULTS

Both EO (WK = 0.67) and IO (WK = 0.64) had good level of decision agreement with and without LCR evaluation. EO did not present a shift towards extraction nor non-extraction with LCR evaluation (McNemar = 0.999) whereas IO showed a tendency to extraction (McNemar = 0.07) with LCR data. Including LCR evaluation created a systematic inconsistency between EO and IO (Line of equality = 0.8, Confidence interval = 0.307-0.707).

CONCLUSIONS

Lateral cephalometric radiograph evaluation did not influence the extraction decision in treatment planning of skeletal Class I patients. Reconsidering the necessity of lateral cephalograms in orthodontic treatment of skeletal Class I patients may reduce the amount of ionizing radiation. Key words: Lateral cephalometric radiograph, extraction, treatment planning, skeletal Class I.

Comparative Evaluation of Nasopharyngeal Airways of Unilateral Cleft Lip and Palate Patients Using Three-Dimensional and Two-Dimensional Methods

Aim

Comparison of nasopharyngeal airway dimensions among UCLP patients and the control group.

Materials and Methods

Computed tomography imaging data and cephalometric films of 20 patients with UCLP and 20 controls were acquired prior to treatment. Three-dimensional (3D) reconstructions of nasal, superior, middle, and inferior pharyngeal airways were carried out from dicom data, and volumes of these compartments were calculated. Nasal width and superior, middle, and inferior nasopharyngeal areas were calculated from cephalometric films.

Results

The only statistically significant difference among the cleft and noncleft patients was detected in nasal volume ( p < .01). Upper and middle pharyngeal airway areas were found to display significant larger areas in the noncleft group on cephalometric appraisal. Nonsignificantly larger nasal widths were measured in the cleft group.

Discussion and Conclusion

Evaluation of the nasopharyngeal airways of cleft and noncleft patients was done, resulting in only the nasal region showing statistically significant difference. Our results showed significantly lower nasal volume measurements of cleft patients when compared with the healthy individuals (p < .01). This inadequacy can be interpreted as an outcome of the deficiency. The controversy among results of cephalometric appraisal and 3D imaging can be associated with superimpositions, density, and contrast inadequacies and obscured landmarks. When 2D data are compared with 3D data, the former can be insufficient and therefore deceiving. Consequently, although the radiation dose of 3D imaging systems is greater, they have the advantage of superior diagnostic outputs.

Free radical scavenging and antioxidative properties of 'silibin' complexes on microsomal lipid peroxidation

The antioxidant properties of silibin complexes, the water-soluble form silibin dihemisuccinate (SDH), and the lipid-soluble form, silibin phosphatidylcholine complex known as IdB 1016, were evaluated by studying their abilities to react with the superoxide radical anion (O2-.), and the hydroxyl radical (OH.). In addition, their effect on pulmonary and hepatic microsomal lipid peroxidation had been investigated. Superoxide radicals were generated by the PMS-NADH system and measured by their ability to reduce NBT. IC50 concentrations for the inhibition of the NBT reduction by SDH and IdB 1016 were found to be 25 microM and 316 microM respectively. Both silibin complexes had an inhibitory effect on xanthine oxidase activity. SDH reacted rapidly with OH radicals at approximately diffusion controlled rate and the rate constant was found to be (K = 8.2 x 10(9) M-1 s-1); it appeared to chelate Fe2+ in solution. In hepatic microsomes, when lipid peroxidation was induced by Fe2+, SDH inhibited by 39.5 per cent and IdB 1016 by 19.5 per cent, whereas when lipid peroxidation was induced by CuOOH, IdB 1016 exerted a better protective effect than SDH (29.4 per cent and 19.4 per cent inhibition, respectively). In both microsomal systems lipid peroxidation proceeded through a thiol depletion mechanism which could be restored in the presence of silibin complexes. Low levels of lipid peroxidation in pulmonary microsomes point out the differences between in-vitro lipid peroxidation occurring in microsomes of different tissues. The results support the free radical scavenger and antioxidative properties of silibin when it is complexed with a suitable molecule to increase its bioavailability.