Abstract
— In this paper, we proposes a machine vision system to approximate  depth  of  drilled  dental  plaster  model  in  training  process  of  young  dentist  and  undergraduate  dentist.  The  system  is  based  on  basic  laser  scanner  and  machine  vision  technique.  The  proposed  system  consists  of  two  main  parts:  an  image  acquisition  process  using  basic  line  laser  scanner  and  depth  measurement  system  based  on  a  right  and  isosceles  triangle.  450  laser  points  on  each  dental  plaster  model  sample  are  extracted  for  testing.  From  our  experimental  result,  our  system  is  more  effectiveness  to  inspect  the  practiced  dental  plaster  model  than  manual  inspection  by  a  senior  dentist.  Our  efficiency  proposed  system is 0.1 mm error in depth on measurement range 0.2 to 1.2 mm depth.
Keywords-laser  beam;  depth  estimation;  skeleton;  3D  model;dental drill machine; machine vision;
I.
INTRODUCTION
A dental drill is an important and basic tool for the dentist in dental treatment; remove infected and polish from teeth [1]. In skill training procedure, dental students are trained by dental plaster models with the dental drill. An inspector, senior dental, rates  their  skill  by  measuring  drilled  plaster  models  with  a  periodontal  probe  in  1  mm.  scale.  This  process  takes  a  long  time.   It   is   subjective   measurement   relying   on   inspector’s   experience,   physical   condition,   and   others.   An   automatic   surface   inspection   by   machine   vision   system   is   role   in   industrial very fast. Many advantages of machine vision system are  non-destructive  testing,  contactless,  high  reliability,  100%  inspection,  real-time  working.  Human  vision  knowledge  is  easily applied to the system.  Normally,  surface  inspection  system  integrates  two  main  parts:  light  source  system  (light  bulb  and  laser  beam)  and  machine  vision  algorithms  [2-10].  For  the  light  bulb,  a  single  light bulb for road surface inspection by using reflected surface characteristics  [2],  multi-color  light  bulbs  for  rail  surface  inspection  by  using  color  surface  characteristics  [3].  Laser  beam   is   applied   for   high   resolution   and   high   quality   applications. One or more laser colors and one or more digital cameras  are  applied  to  increase  performance  [4,  5],  a  mobile  car  laser  scanner  for  road  surface  inspection  system  [6,7],    surface  of  metal  steel  inspection  system  which  detects  shiny  and smooth surface of iron sheet [8,9], sphere defect detection by using 3D model [10], and others. These applications help to improve  speed,  precision,  and  accuracy  of  inspection  system.
However, some system is complicated and expensive.   In  this  paper,  we  present  a  simple  dental  plaster  model  inspection  system.  In  Section  II  presents  inspection  system  prototype and image acquisition, followed by our implemented system in Section III, and finally experimental result in Section IV.dental laser tips
II.INSPECTION SYSTEM AND IMAGE ACQUISITIONA.Inspection System Prototype Distinguished laser properties are very high luminance and narrow band, which is not been disturbed by other light sources and reflection patterns: diffuse, nearly ideal specular and mixed diffuse,   and   specular   reflection   [11,   12].   In   our   system,      we  design  a  simple  system  which  is  based  on  basic  laser  scanner ideal using a line laser beam as a light source shown in Fig. 1.
shows  efficiency  of  our  system.  450  testing  points  from  the  dilled  dental  plaster  model  are  measured  by  dual  gauge  for  'real  depth  measurement'  and  our  introduced  system for “depth approximation”. Error rates of the real depth measurements  and  depth  approximations  are  compared  and  shown  in  Table  I.  In  term  of  effectiveness  measurement  is  shown in Table II. Our introduced system works faster than an expert inspection with 3 times.       
In   this   paper,   we   introduced   an   automatic   system   to   inspection  dental  plaster  model  examples  for  young  dental  practice  and  undergraduate  dentist  by  basic  laser  scanner  and  machine  vision  techniques.  The  system  reduces  amount  of  verifying  and  scoring  the  practice  dentals  and  also  provide  high accuracy. Future work, variation of dental practices such as  smooth  drilled,  curve  drilled,  sine  wave  drilled,  and  others  will be integrated to create a method to measuring and scoring model for young dental practice scoring.
This research is support by faculty of engineering, Prince of Songkla  University  (PSU).  We  would  like  to  acknowledge  all  suggestions from all researchers at intelligent system laboratory (iSys), department of computer engineering, PSU.