الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
This randomized clinical trial was conducted to introduce and evaluate a new technique using CAD/CAM additive manufacturing in the direct construction of one-piece closed hollow bulb obturators and compare them to conventional heat-cured acrylic resin obturators for patients with acquired maxillary defects.
Twelve patients; ten females and two male patients, that were partially dentate with unilateral maxillary surgical defects with extensions following Aramany’s classes I or II that were indicated for construction of hollow bulb obturators were selected for this study. All surgical defects were healed with at least six months elapsed from the completion of the surgical and/or adjunctive treatment. All patients were non smokers and patients’ ages ranged from 20 to 60 years.
Patients were randomly allocated to two equal groups (n=6), group A (Study) and group B (Control). For every patient in group A, two obturators were fabricated using CAD/CAM additive manufacturing and conventional heat-cured acrylic resin. While for group B patients, conventional heat-cured acrylic resin obturators were fabricated.
During six months follow up period, digital evaluations were carried out to calculate obturators dimensional deviations and to quantify obturators tissue misfit. Patients’ acoustic evaluation of speech was carried out using Computerized Speech Lab. Acoustic nasality evaluation was also made for all patients participated in this study using the Nasometer. Obturators weights were recorded on timely basis using a laboratory analytical balance. Microbiological evaluation for patients’ mucosal foundation and their obturators were carried out monthly to isolate, identify and count various bacterial and fungal isolates. Oral assessment guide and Kapur’s index were used to clinically evaluate patients and their obturators. Patients’ degree of satisfaction was evaluated using the obturator functioning scale.
The resulting dimensional deviations within group A at day of delivery were statistically significant negative values for CAD/CAM obturators with highest values recorded at teeth surfaces under any used registration reference. Heat-cured obturators showed statistically significant positive deviation values with highest values at teeth and polished surfaces. The resulting deviations of both groups after sixth month were statistically insignificant positive values that were highest at teeth surfaces.
The resulting tissue misfit of obturators of group A at day of delivery was of statistically insignificant lower values for CAD/CAM obturators. The highest misfit values were recorded at the oral surfaces of both obturators.
Acoustic assessment of patients’ speech formant frequencies F1and F3 of vowels /a/, /i/ and /u/ showed that frequency values without the obturators were always significantly higher than those with the obturators. F1 frequencies of vowels /a/ and /u/ at delivery appointment with the obturators were significantly higher than those after third month of follow up, while F3 frequencies were lowest for third month of follow up for any test vowel. F2 values were significantly lower for all test vowels without the obturators than with the obturators, and were significantly lower at delivery appointment with the obturators than those after third month of follow up for vowel /a/ only. When both groups were compared, group A showed higher percent of change values for F1, higher values for vowels /a/ and /u/ for F2, and lower values for F3.
The Nasometric assessment revealed that the use of obturators in both groups showed a decrease in nasality values for all test sounds; vowels, consonants, and test sentences. A general decrease in nasality, although not always significant, for all test sounds was observed between delivery appointments with the obturators and the third month of follow up. When both groups were compared, group A obturators, although mostly insignificant, showed higher improvement values.
The resulting weight values of obturators of group A showed that CAD/CAM obturators were significantly lighter in weight than Heat-cured ones. The results of weight changes of both groups showed that heaviest weights were recorded when obturators were retrieved and initially weighed at sixth month of follow up. No fluid accumulations within bulbs of obturators of both groups were detected. Statistically significant lower water sorption and insignificant lower material loss values were calculated for CAD/CAM obturators of group A.
The results of microbial isolation and identification revealed that 11 bacterial and fungal isolates were identified. Isolation frequencies were insignificantly higher for Staphylococcus aureus, Viridans streptococci, Non-hemolytic streptococci, and Bacillus cereus, significantly higher for Klebsiella pneumoniae and Pseudomonas aeruginosa, insignificantly lower for Streptococcus mutans, Staphylococcus epidermidis, Streptococcus pyogenes and Bacteroides, and significantly lower for Candida albicans in group A. For microbial counting, group A generally showed higher counts for all test periods which were statistically significant different for only the fourth and sixth months of follow up. All samples obtained from bulb cavities of obturators of both groups were sterile.