Since root resorption is a frequent consequence of orthodontic treatment, DSP are non-collagenous dentin-specific matrix proteins postulated to be involved in the mineralization of pre-dentin into dentin. Calculating the amount of DSP -Dentine Sialo Protein- produced upon root resorption might be an indicative biological marker for root resorption

Histological and radiographic observations have shown that root resorption is a frequent consequence of orthodontic treatment (Reitan, 1974; Rygh, 1977; Harry and Sims, 1982). In most patients this resorption is minor and of no importance. A few teeth however exhibit severe resorption. In a study by Goldson and Henrikson (1975) it was found that 6 per cent of 924 teeth were resorped more than 2 mm after treatment with a Begg appliance and Malmgren et al. ( 1982) found a similar degree of root resorption in 10 percent of 264 incisors treated with an edgewise appliance and in 5 percent of 176 incisors treated with a Begg appliance(1).

Root resorption resulting from undesirable orthodontic force is an unwanted sequele , that fears all orthodontists including their experts as well(2).

DSP are non-collagenous dentin-specific matrix proteins postulated to be involved in the mineralization of pre-dentin into dentin (3,4) .Dentin undergoes continuous deposition throughout life as a secondary dentin only on the pulpal surface. Therefore, these proteins are not routinely released into the surrounding space as dentin does not undergo the process of remodeling as in bone. It is only in the presence of active external root resorption that these proteins could be freed into the periodontal ligament space(5).

Since periapical -intraoral- radiograph gives a two dimensional information, which detect root resorption after 60- 70% of the mineralized tissue is lost. (6) So, it's not sensitive in detecting early root resorption so in this study the investigators introduce the biological marker DSP to monitor root resorption from its onset by collecting samples from the GCF -gingival crevicular fluid- for its detection.

Calculating the amount of DSP -Dentine Sialo Protein- produced upon root resorption might be an indicative biological marker for root resorption.

Inclusion Criteria:

• Adolescent female patients age ranging from 15- 18 yrs, with the full set of the permanent dentition.
• No previous orthodontic treatment.
• Class I crowding or Class II malocclusion whose treatment requires extraction of first maxillary premolars.
• Adequate oral hygiene.

Exclusion Criteria:

• Systematic diseases.
• Bad Oral hygiene.
• Missing permanent teeth (except for third molars).
• Uncontrolled Pathological Conditions that may contra-indicate immediate orthodontic treatment (caries, gingivitis, periodontitis).