Create A Function To Remove Dirty Words From User Input Text?

I am trying to create a function to remove dirty words from user input text and want to replace those dirty words with four ****. In my scenario , i have list of dirty words where i would iterate the input user text and want to replace. Say for example.,

Dim InputTxt As String = "hi bush how are you.... $hit and @ss"
Dim OutPut As String = " hi **** how are you... **** and ****";

Problem: It works fine to replace some word like " bush" however fails in the below function doesn't replace "$hit" and "@ss".

Note: I do not want to use string.Replace because it doesn't have word boundary in the sentence..

Public Function pReplaceWords(ByVal dirtyWord As String, ByVal inputText As String, ByVal options As RegexOptions) As String
Try

[Code]....