Trial design and setting
The study was designed to be crossover clinical trial.
Six partially edentulous patients having unilateral total maxillectomy defects approaching midline (class I Aramany classification) were selected from the outpatient clinic, Prosthodontics Department, Faculty of Oral and Dental medicine Cairo University or referred from the National Cancer Institute.
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Control group (Group I): all the patients first received definitive obturator which fabricated using conventional heat cured acrylic resin.
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Study group (Group II): after that the obturator was removed from all the patients and then relined with heat cured soft silicone material.
Trial registration
The study protocol was approved by Evidence-based Dentistry Committee, Prosthodontics Department Board and Ethics Committee of Faculty of Oral and Dental Medicine, Cairo University.
Eligibility criteria
Inclusion criteria
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1.
Partially edentulous patients having unilateral total maxillectomy defects approaching midline.
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2.
At least four months were elapsed from the date of surgery.
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3.
Adult patients with age ranged between 20 and 60 years old with an average age of 45 years.
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4.
All patients had a full set of natural teeth on the intact side of the arch and intact opposing arch.
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5.
Cooperative patients and follow the instructions.
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6.
Remaining palatal mucosa was free from inflammatory conditions.
Exclusion criteria
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1.
Patients with systemic disorders that might disturb oral ecology were excluded, such as diabetes mellitus, blood diseases, T.B.
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2.
Patients were not receiving chemotherapy or radiotherapy or any drugs that could affect bacterial balance during the study period.
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3.
Smoking patients. Because it will affect the healing process.
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4.
Uncooperative patients. Because it will not return for follow-up
Patient examination
Patient's assessment was done to determine whether the patient met the study inclusion criteria. These assessments include a medical history questionnaire, a clinical examination, and radio-graphic assessment.
Patient consent form
Diagnostic data, suggested treatment and alternatives were reviewed with participants for this study. Illustrative consultation, treatment period, prosthodontics device and ultimate difficulties as well as hazards were all written in a consent form. The patients were fully educated about the possible consequences of the proposed research and signed a special written consent form designed for this purpose. All patients were requested to sign an informed consent form; this was translated into the Arabic language to be understood by the patients. The trial was conducted in accordance with the Declaration of Helsinki (2008).
Interventions and study procedures
A conventional obturator was fabricated for all patients following the traditional steps.
Construction of the definitive obturator
A suitable maxillary perforated stock tray was selected according to patient arch form and size. The tray was modified either by reduction or addition of modeling waxFootnote 1 in order to cover the area of defect and allow the impression material to extend to the required borders.
Training appliances and muscle relaxants were prescribed for patients suffering from trismus. Topical anesthesia was applied to the defect to reduce pain during procedure and undesirable undercuts were blocked out with vaselinated gauze.
Upper and lower primary impressions were made using irreversible hydrocolloid impression material and poured into dental stoneFootnote 2 to obtain study casts.
SurveyingFootnote 3 of the maxillary diagnostic cast was carried out.
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A.
Mouth preparation
Mouth preparation was done according to the planned design.
Support
Support was achieved through the palatal plate major connector, in addition to multiple occlusal rest seats were prepared distal to the first premolar, mesial to the second premolar, distal to the first molar and mesial to the second molar. A cingulum rest was prepared just above the cingulum of the canine tooth.
Retention
Retention was achieved through double Aker’s clasps on the premolars and molars with alternating buccal and lingual retention.
Bracing and reciprocation
Bracing and reciprocation were obtained through the double Aker’s clasps and the minor connectors.
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B.
Final impression
A custom made acrylic tray with wax spacerFootnote 4 was fabricated with a wax spacer. Any undesirable undercuts in the defect side was blocked out using vaslinized gauze.
A rubber base adhesive was applied to the fitting surface of the special tray and the final impression was made using medium body rubber base.Footnote 5
The Impression was disinfected and assessed for extension, anatomical landmarks, rolled borders and surface details.
The final impression was then boxed and poured into dental stoneFootnote 6 to obtain the master cast.
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C.
Framework construction
On the obtained master cast, relief and block out were made. The planned design was then transferred to the refractory cast and wax pattern was fabricated.
The Refractory cast was then invested, burnt out and cast. Framework was trimmed, finished, polished and tried in the patient’s mouth.
The fitting surface of the metal framework was coated with pressure indicating paste (PIP)Footnote 7 before insertion and any interference was eliminated. It was checked for fitness, retention, extension, stability and finally it was checked for occlusion.
After metal framework try in, framework with trial denture base and occlusal rim were fabricated.
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D.
Centric relation record and setting up of teeth
The Framework with trial denture base and occlusal rims were inserted in the patient's mouth and asked to close with gentle force on softened waxFootnote 8 so that the occlusal imprints of the opposing teeth are recorded. Then the upper and lower casts were mounted on a semi adjustable articulator.Footnote 9
The teethFootnote 10 shade, size and form were determined; setting up of artificial teeth was carried out and arranged following the guide lines of the lingualized concept of occlusion.
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E.
Final try in stage
The waxed up definitive obturator teeth was tried in patients mouth and checked for retention and comfort. Extension of the posterior and lateral borders of the obturator and restoration of the normal facial contour were also evaluated.
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F.
Processing of the obturator
Definitive obturators were fabricated using conventional heat cured acrylic resinFootnote 11 (group I). During packing a hollowed obturator bulb was constructed using the lost salt technique. A long curing cycle was performed (74 °C for 9 h).
Adequate time was allowed for proper cooling of the flask after curing prior to the deflasking procedure. The obturator was highly finished and polished.
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G.
Obturator insertion
Finished obturator was checked carefully for blebs, bubbles, artifacts in either metal or acrylic and borders were checked for sharp edges.
At the time of delivery (Figs. 1, 2), the prosthesis was checked intra-orally for proper extension, retention, adaptation, pressure areas, and occlusion. The patient was instructed to come back in the next day and any necessary adjustment was carried out.
Patient instructions
One week before obturator insertion, patients were instructed to remove the interim prosthesis all day except during eating, perform Chlorohexidene mouthwash in addition to Penicillin 500 mg. and Metronidazole 500 mg, during this period any other medications that might alter the oral flora were avoided.
After obturator insertion, patients were instructed to wear the prosthesis during daytime, eating and to be removed from mouth for approximately 8 h daily (sleeping hours) to reduce trauma to the underlying mucosa. Patients were instructed to avoid any medications or mouthwashes.
The prosthesis should be cleaned after each meal under running water over a basin filled with water to avoid accidental drop and breakage. While not in use it should be placed in a container with tap water.
Microbiological samples for obturator with heat cured acrylic resin bulb
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At time of obturator insertion: one swab was taken from each patient from the nasal surface of the surgical cavity. It was considered a base line for each patient.
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After obturator insertion: one swab was taken at the following follow-up periods:
Relining of the obturator
After the fourth week swab was obtained, 2 mm of the heat cured acrylic resin bulb were reduced and the obturator was relined with chair side soft liner.Footnote 12 The patients were instructed not to remove the prosthesis for the next 48 h and come back for further relining procedures.
While prosthesis still in place, an overall impression using a hydrocolloid impression materialFootnote 13 in a perforated stock tray was done. The obtained cast with the obturator was flasked. After deflasking, the chair side soft liner was replaced with heat cured soft silicone materialFootnote 14 (group II) prior to application of silicone liner an adhesive primer with a solvating effect must be used on the denture base.
At the time of delivery, the prosthesis was checked intra-orally for proper extension, retention, adaptation, pressure areas, and occlusion. The patient was instructed to come back in the next day to adjust any problem related to the prosthesis (Fig. 3).
Microbiological samples for obturator with heat cured silicone bulb
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At time of obturator insertion: one swab was taken from each patient from the nasal surface of the surgical cavity. It was considered a base line for each patient.
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After obturator insertion: one swab was taken at the following follow-up periods:
Microbiological procedures
For all patients, microbiological samples were collected and evaluated by semi quantitative culture of microorganisms in the following manner.
Isolation of microorganisms was carried out using gamma sterilized disposable swabs (Fig. 4).
Microbial growth evaluation was made as following:
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The swabs were emulsified in 1 ml sterile nutrient broth then after good shaking; it was added to 9 ml nutrient broth in a sterile tube making a dilution of 1:10.
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Serial dilutions were done to reach a dilution of 1: 1000.
20 micron from the nutrient broth was taken by micropipette (Fig. 5) and applied to the surface of Sabouraud Dextrose Agar plate, another 20 micron to Blood Agar and Macconkey plates and distributed on them by glass rod. Then these plates were incubated at 37 °C for 24 h in an incubator.
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After incubation, the plates were examined for the growth of Candida on Sabouraud Dextrose Agar plates, Staphylococcus aureus on Blood Agar plates and Gram negative on Macconkey plates. Colony Forming Unit (CFU) were counted (number of Candida, Staphylococcus aureus and Gram negative /sample was calculated)
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Identification was done by morphological examination and gram-staining.
Morphological examination: Candida (Fig. 6)
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Appear on Sabouraud Dextrose Agar plates as cream colored pasty colonies.
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The Colonies have a distinctive yeast smell.
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Appear as large dark violet budding organisms in gram stain.
Staphylococcus aureus (Fig. 7)
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Appear on Blood Agar plates as yellow or occasionally white 1–2 mm in diameter surrounded with a clear zone of complete hemolysis (β hemolysis).
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Pigment is less pronounced in young colonies.
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Colonies are slightly raised and easily emulsified.
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Appear as gram positive cocci arranged in clusters.
Gram negative bacteria
Statistical analysis
In this study, data of Candidal and Bacterial colonies were coded, edited, collected, and analyzed as means and standard deviations for both groups (before and after relining) before insertion as base line, 2 weeks and 4 weeks follow-up periods.
Statistical analysis was carried out using Microsoft Excel 2010 program. While testing significance was performed using SPSS® 20 (Statistical package for scientific studies, SPSS, Inc., Chicago, IL, USA) and Minitab ® statistical software Ver. 16.
Collected values were calculated according to the equation, CFU/ul = Total number of colonies counted in the plate X inversion of the saline dilution (1000)/10.
Data were explored for normality using Kolmogrov-Smirnov test and Shapiro–Wilk test. Exploration of data revealed that the collected values were not normally distributed.
Kruskal–Wallis test followed by multiple comparisons test were performed to test the significance between the follow-up periods within each group to detect the effect of time on candida and bacterial growth.
In addition, Mann–Whitney U test was performed to test the significance between both groups at each follow-up periods to compare the candida and bacterial growth between both groups.
A probability level of P ≤ 0.05 was considered statistically significant.