Comparative evaluation of image quality, colour accuracy and resolution of intra-oral photographs made using a DSLR camera with macro lens and smartphone cameras

**NEED FOR THE STUDY:**Photography is a widely used medium for recording data in various fields including medicine and dentistry. The continuously evolving modern-day technology leads to a revolution in photographic standardization. Communication with lab technicians (shade matching, teeth selection), high-resolution pictures for research publications, patient education, and data recordings are some of the major applications of photography in the noble field of dentistry. Nowadays, many clinicians prefer their smartphone cameras to record case, intra-oral and extra-oral pictures over DSLR cameras. Owing to the advantages like easy to handle, being cheap comparatively, and providing a wide range of editing options, there is still a big question mark on the accuracy, resolution, distortion and quality of the images captured using a smartphone device camera. Hence, in the evolving world of digitalization, there is a need for this study to know where the standard of mobile phone photography lies, and to what extent it can be used efficiently for recording intra-oral and extra-oral photographs in the field of dentistry.

**RESEARCH QUESTION:**To assess the differences in image quality, distortion, magnification of images, colour accuracy, and resolution (in pixels per inch) of images captured by a DSLR camera set up for intraoral photography and different smartphone devices available currently in the market.

**HYPOTHESIS (ALTERNATE/NULL): NULL HYPOTHESIS:**The null hypothesis states that there will be no difference in the image quality, distortion, magnification of images, colour accuracy, and resolution (in pixels per inch) of images captured by a DSLR camera set up for intraoral photography and, iPhone 15 PRO smartphone camera, a Google Pixel 8 smartphone camera and Samsung S24 ultra smartphone device camera.

**AIM:**The study aims to compare the image quality, distortion, magnification of images, colour accuracy, and resolution (in pixels per inch) of images captured by a DSLR camera set up for intraoral photography, an iPhone 15 PRO smartphone camera, a Google Pixel 8 smartphone camera and Samsung S24 ultra smartphone camera under optimal light conditions.

OBJECTIVES:

1.      To evaluate and compare the distortion of the image by measuring the dimensions of the Maxillary Central incisor (height* width) captured by a DSLR Camera, iPhone 15 Pro, Google Pixel 8 and a Samsung S24 Ultra smartphone device.

2.      To evaluate and compare the extra-oral magnification of the image by measuring the inter-canthal distance from the image captured using a DSLR camera, iPhone 15 Pro, Google Pixel 8 and a Samsung S24 Ultra smartphone device.

3.      To evaluate and compare the intra-oral magnification of the image by measuring the inter-canine distance from the image captured using a DSLR camera, iPhone 15 Pro, Google Pixel 8 and a Samsung S24 Ultra smartphone device.

4.      To evaluate and compare the colour of teeth using the HSV (Hue, saturation, value) values for the maxillary central incisor through an image captured via DSLR camera, iPhone 15 Pro, Google Pixel 8 and a Samsung S24 Ultra smartphone device.

5.      To evaluate and compare the picture resolution obtained in pixels per inch (PPI) for images captured using a DSLR camera, iPhone 15 Pro, Google Pixel 8 and a Samsung S24 Ultra smartphone device.

 METHODOLOGY:

STUDY DESIGN: Cross-sectional study design.

STUDY SITE: Department of Prosthodontics, Crown and Bridge, Yenepoya Dental

College, Mangalore.

FUNDING DETAILS: Self-funded

STUDY DURATION: 2 months. (October-November 2024)

 SOURCE OF DATA:

·        Out-patient department of Yenepoya Dental College, Mangalore.

·        After selecting the participants, they will be informed about the study details in the language they understand. (Annexure I)

·        Participants will be asked to sign the consent letter of participation. (Annexure 4).

 SAMPLE SIZE:

Using G* Power software, under ANOVA, it is suggested to collect data from 10 patients with 4 measurements in each patient (10*4=40) at 95% confidence level and 80% power. The effect size=0.5621 is calculated using mean and standard deviations reported in the literature by Saincher R et al. (2022). [3]

 METHOD OF SAMPLING (SAMPLING TECHNIQUE):

Convenience sampling method.

 INCLUSION CRITERIA:

1.      Dentulous participants with a complete set of teeth

2.      Male and female participants within the 18-50 years age group.

3.      Participants those who agree with the informed consent.

 EXCLUSION CRITERIA

Participants with prosthetic rehabilitation in the anterior tooth region, and ongoing orthodontic treatment.

Participants with malocclusion anomalies like crowding of teeth, rotation and spacing of teeth.

WITHDRAWAL CRITERIA

Participants have the right to withdraw from the study at any time.

 DISCONTINUATION CRITERIA

Participants having any kind of identity issues with their photographs may be included in the discontinuation criteria.

 STUDY TOOL:

Static photographic records

 DESCRIPTION (QUESTIONNAIRE; INTERVIEW SCHEDULE; SCALES; SCORES; DATA COLLECTION FORM; PROFORMA; ETC)

Data collection form.

METHOD:

DETAILS OF THE METHODOLOGY INCLUDING DETAILS OF SAMPLE COLLECTION:

A. Materials and Armamentarium

Armamentarium:

Nikon Z50 HDSLR Camera with 100mm lens and Macro Twin lite MT-24EX

I-phone 15 PRO

Google Pixel 8 smartphone

Samsung S24 Ultra

 Materials:

Cheek retractors

Black contrastor

Black chart paper

Intra-oral mirror

Methodology:

Participants will be recruited from the outpatient department of Yenepoya Dental College. An informed consent sheet and participant information sheet will be provided and the study procedure will be explained to them prior.

 Study groups:

Control group: Nikon Z5 DSLR with 105mm macro-lens and Twin lite MT-24EX flash.

Case group:

Group 1) iPhone 15 pro smartphone.

Group 2) Google Pixel 8 smartphone.

Group 3) Samsung S24 Ultra smartphone.

 Pictorial records: 5 sets of images per participant.

1. Maximum Intercuspation image

2. Anterior teeth with black contrast image

3. Right lateral occlusion image

4. Mandibular occlusal view using intra-oral mirror

5. Extra-oral portrait image

Method: the participant is seated on a dental chair; informed consent is provided.

A plastic cheek retractor is used to provide sufficient retraction, and isolation is done with

suction tips.

Intraoral mirrors are used to record the images.

5 sets of images are captured for a participant per group.

Light conditions are standardized as daylight conditions.

DSLR Camera with a 100mm macro lens is used as the control group, the device is used at a faster shutter speed (200), longer focal length (f/25), magnification of 1:2 and higher aperture size for intra-oral pictures.

For extra-oral portrait pictures, the DSLR camera is set at shutter speed (60), focal length(f/10), and magnification ratio of 1:10.

The mobile phone groups (iPhone, Google Pixel 8 and Samsung S24 ultra) are used in auto-focus mode, at a standardized zoom(2x) and equal focal length (25cm) for all the groups.

Each intra-oral image is cropped (4:3) and the extra-oral image (3:4) in JPEG file format is uploaded to a secured folder in the investigator’s laptop for data analysis.

 Data measurement:

Distortion of the image will be evaluated in the Maximum intercuspation image by measuring the dimensions (height in mm) of the maxillary right central incisor using digital software GIMP Version 2.1 for the control and case group.

Extra-oral Magnification will be checked by measuring the intercanthal distance (in mm) for each frontal view image captured in portrait mode using the same software.

Intra-oral Magnification will be evaluated by measuring inter-canine width (in mm) in the mandibular occlusal view picture for each participant.

The resolution of the image will be measured in DPI (dots per inch) in the Right lateral occlusion picture using GIMP 2.1 software.

Shade evaluation: manual method:

The anterior teeth with black contrastor image will be used.

The shade of anterior teeth (preferably Maxillary right Canine) in all the test-group images will be compared with the control group by the investigator.

HSV values will be obtained using digital software (GIMP 2.1) for better correlation with the colour of the selected tooth.

All the readings obtained from the pictures will be stored efficiently in a data collection sheet (Microsoft Excel) for further statistical analysis.

 DETAILS OF ANALYSIS: (Including statistical tests):

Data points will be coded in MS Excel and all statistical analysis will be done using IBM SPSS 27 software.

The Shapiro-Wilk test will be used to check the normality.

The summary of quantitative variables will be presented using counts, mean or median and standard deviation/interquartile range depending on normality.

The significant difference between the four groups of measurements will be assessed through one-way ANOVA or the Kruskal Walli test depending on normality. If the null hypothesis is rejected, then post hoc tests are to be carried out for pair-wise comparisons.