Study design
A randomized clinical trial design was adopted in this present research.
The study setting
Clinical procedures were performed at Pediatric Dentistry Department, Tanta University.
Sample size calculation
The sample size was calculated by using Epi-Info computer software version 7, assuming that confidence level at 95% with 5% margin of error and design defect in power analysis in two calculated samples was 20 patients.
Ethical considerations
The purpose of this study was explained to the parents and they were informed that all prepared abutment teeth would be compensated by single crowns after removal of the bridge to protect them until exfoliation time then written informed consents were obtained from the parents according to the guidelines on human research performed by the Internal Research Ethics Committee, Faculty of Dentistry, Tanta University (info_REC@dent.tanta.edu.eg).
All methods were performed in accordance with the relevant guidelines and regulations.
Approval of the trial protocol
The trial protocol was approved by the Internal Research Ethics Committee, Faculty of Dentistry, Tanta University in 2/11/2022.
Study sample and group assignment
A total of forty preschool children from both genders aged between 3–5 years old were selected and randomly assigned (Through closed envelopes) into two groups as follow:
Group I (study group): Twenty preschool children used a modified fixed bridge in their anterior extraction site. (Fig1, 2, 3)

Premature loss of upper ant teeth.

Rehabilitation of extraction site with modified fixed bridge.

Palatal view of modified fixed bridge.
Group II (control group): Twenty preschool children used a modified Nance appliance in their anterior extraction site. (Fig4, 5)

Premature loss of upper ant teeth.

Rehabilitation of extraction site with modified Nance appliance.
Inclusion criteria6:
Healthy cooperative children
Children with normal occlusion
Sound abutment teeth (Primary canines)
Premature loss of primary incisors due to trauma or damaged stage of rampant caries
children from both genders aged between 3–5 years old were selected
Exclusion criteria7:
Medically compromised children or children with special needs.
Permanent teeth were near to eruption as evaluated in x-ray film.
Badly destructed abutment teeth or exhibit root resorption as appeared in preoperative x-ray.
Children with bruxism or abnormal habits.
Children with abnormal occlusion like cross-bite or deep-bite
Practical procedures
Group I
Each child was examined carefully to be compatible with inclusion criteria then preoperative preapical x-ray film was captured to assess stage of succedaneous teeth development, ensured that there were not any root fragments of primary incisors and evaluated the roots of abutment teeth.
Topical anesthesia was applied before administration of local anesthesia for abutment teeth before preparation. Then preparation of abutment teeth was carried out according to manufacturing instructions for acrylic fixed bridge (Polymethyl methacrylate acrylic (PMMA)) by using tapered diamond bur (Komet® 8862.FG.010, Feather Edge Diamond Preparation Bur, Germany). As conservative preparation was followed, first incisal reduction (1–1,5mm) was performed to obtain incisal clearance then vertical grooves was applied on labial and lingual surfaces by feather edge diamond bur to guide the amount of the required reduction then follow uniform and anatomical reduction in all surfaces while tapered diamond bur was parallel to long axis of the abutment tooth, consequently reduction with slight incisal convergence was obtained. Finally smoothness of all sharp edges was performed. (Fig. 6).

Schematic figure of the prepared tooth.
Impression with putty rubber base material was taken (Zhermack Zetaplus Putty Impression Material, Germany) according to manufacturing instructions as was placed into an impression tray; then they were both inserted into child mouth and pushed onto their teeth in order to take an impression. Once the dental putty was set the impression was removed. An impression was also taken of the opposing teeth, so the technician could see how child bite together. A temporary crown (Charm Temporary CrownR ) was cemented onto the prepared tooth by (Charm Temporary cement) to protect them until the bridge was being fabricated. The impressions were sent to the dental laboratory.
A modification was carried out in the bridge by split it through midline into two segments, then 1cm of stainless steel wire with diameter 0.8 mm was embedded into one segment (Male part) with free end, while the other segment a small tunnel was prepared to allow insertion of free end of the stainless steel wire into it (Female part) (Figs. 7, 8).

New Modified fixed bridge.

New Modified fixed bridge.
After fabrication of the modified bridge, it was received from the lab then temporary crowns were removed and the prepared abutment teeth were totally cleaned from any cement. Finally, the appliance was cemented with conventional glass ionomer cement.
Group II:
The first step was done in group (I) was performed, then primary impression was taken for selection appropriate stainless-steel bands on second primary molars. After proper adaptation of the bands, secondary impression was taken and sent them to the dental laboratory for construction of modified Nance appliance.
A modified Nance appliance was constructed by 0.9 mm rigid stainless steel wire welded to each band then extended to the raugae area of hard palate where heat cure acrylic resin poured into it, then part of the acrylic resin extended into alveolar ridge as artificial acrylic teeth would embedded in the acrylic resin. Figure 5
Evaluations of maxillary development for both groups were assessed by measuring the inter-canine arch width as a parameter of anterior maxillary growth immediately (base line) after insertion of appliances, at six and twelve months follow up. Also, parental satisfaction about performance of each appliance was evaluated at the end of the study by questionnaire similar to one used by Kupietzky and Waggoner8.
The questionnaire was mentored for ease of understanding on forty parents who attended the pediatric dentistry clinics Faculty of Dentistry, Tanta University. A trained dental practitioner explained the questionnaire to the accompanying parent. Also treated children were not present during the interview time. The parents evaluated their child’s restoration directly.
Measurement of inter-canine arch width was carried by Digital vernier caliper
First, dental casts that were obtained by taking an impression after insertion of appliances immediately, six and twelve months follow up.
Marking of reference points on the dental casts were performed by a sharp lead pencil on cusp tips of each upper primary canine, so inter-canine arch width could be measured as distance between two cusp tips by Digital vernier caliper (Zurcher model 042,751, Dentaurum, GmbH & Co., Ispringen, Germany). Figure 9.

Measurement of inter-canine arch width by Digital caliper.
A single examiner was responsible for performing all measurements to avoid any intra-observer error. The intra-examiner repeatability of the measurements was determined to be 0, 2 or less.
To evaluate any error in identification of the landmark, five dental casts were randomly selected and measured twice by the same examiner over period of one week.
Data analysis
Shapiro–Wilk test used to test the normal distribution of the data. Statistical analysis of all data were done using SPSS 24 (IBM, Armonk, NY, United States of America) after they were collected and tabulated. Independent-samples t-test was used when comparing between two groups. Paired t-test was used when comparing between two times in same group. Chi-square (X2) test was used in order to compare proportions between two qualitative parameters.