A dental hygiene detection apparatus for detecting the presence of a substance on a surface, the detection apparatus comprising: a distal oral insertion portion defining a proximal end and a distal end, the distal oral insertion portion including: a distal optical gum detector transmission portion defining a proximal end and a distal tip, the distal tip of the distal optical gum detector transmission portion extending to the vicinity of the distal end of the distal oral insertion portion; and a distal optical gum detector reception portion defining a proximal end and a distal tip, the distal optical gum detector reception portion extending to the vicinity of the distal end of the distal oral insertion portion, the apparatus being configured such that the distal optical gum detector transmission portion and the distal optical gum detector reception portion are in a position to transmit and to receive, respectively, an optical signal that upon transmission of the optical signal and reception of the optical signal by a controller, characterized in that the distal oral insertion portion further comprises a distal probe portion of a stream probe configured to be immersed in a first fluid, the distal probe portion defining a distal tip having an open port to enable passage of a second fluid (30, 35) therethrough, the open port of the distal tip having a size and shape configured to detect a substance that may be present on a surface (31, 33), wherein the apparatus is configured such that passage of the second fluid through the distal tip of the distal probe portion enables detection of a substance that may be present on the surface (31, 33) based on measurement of a stream probe signal correlating a substance at least partially obstructing the passage of fluid (30, 35) through the open port of the distal tip of the distal probe portion, and wherein the controller is enabled to determine if the open port of the distal tip of the distal probe portion is in contact with a substance at least partially obstructing the passage of fluid (30, 35) through the open port and not in contact with the gums of a subject or of a user of the detection apparatus. a distal oral insertion portion defining a proximal end and a distal end, the distal oral insertion portion including: a distal optical gum detector transmission portion defining a proximal end and a distal tip, the distal tip of the distal optical gum detector transmission portion extending to the vicinity of the distal end of the distal oral insertion portion; and a distal optical gum detector reception portion defining a proximal end and a distal tip, the distal optical gum detector reception portion extending to the vicinity of the distal end of the distal oral insertion portion, a distal optical gum detector transmission portion defining a proximal end and a distal tip, the distal tip of the distal optical gum detector transmission portion extending to the vicinity of the distal end of the distal oral insertion portion; and a distal optical gum detector reception portion defining a proximal end and a distal tip, the distal optical gum detector reception portion extending to the vicinity of the distal end of the distal oral insertion portion, the apparatus being configured such that the distal optical gum detector transmission portion and the distal optical gum detector reception portion are in a position to transmit and to receive, respectively, an optical signal that upon transmission of the optical signal and reception of the optical signal by a controller, characterized in that the distal oral insertion portion further comprises a distal probe portion of a stream probe configured to be immersed in a first fluid, the distal probe portion defining a distal tip having an open port to enable passage of a second fluid (30, 35) therethrough, the open port of the distal tip having a size and shape configured to detect a substance that may be present on a surface (31, 33), wherein the apparatus is configured such that passage of the second fluid through the distal tip of the distal probe portion enables detection of a substance that may be present on the surface (31, 33) based on measurement of a stream probe signal correlating a substance at least partially obstructing the passage of fluid (30, 35) through the open port of the distal tip of the distal probe portion, and wherein the controller is enabled to determine if the open port of the distal tip of the distal probe portion is in contact with a substance at least partially obstructing the passage of fluid (30, 35) through the open port and not in contact with the gums of a subject or of a user of the detection apparatus.