The Prospective Observation Of The Clinical Effect Of Minimally Invasive Crown Lengthening Combined With Nanoresin On Repairing The Subgingival Wedge-shaped Defect

Wedge shaped defect?WSD?is commonly referred to as"non-carious tooth neck surface defect".It is a kind of non-carious tooth neck hard tissue disease,which is a"V"shaped defect formed by the long-term external force on the tooth neck hard tissue at the gingival margin^[1].In oral clinical work,the cervical margin of the tooth is the common area of the defect^[2],which is usually divided into supragingival wedge defect and subgingival wedge defect.At present,the main treatment methods for supragingival and subgingival wedge-shaped defects are filling repair.According to the analysis of the position of the gingival marginal wall of wedge-shaped defect,when the gingival square of wedge-shaped defect is less than 0.5mm from the gingival groove base,we usually use the method of direct filling when the gingival margin of the whole mouth is healthy.However,due to the stimulation of materials and the removal of surface stain layer,the biological width may be violated during operation or repair,and cause a series of periodontal problems^[3-4].In recent years,with the continuous development of oral surgery and the continuous progress of microscopy,such defects can finally be repaired through the reconstruction of Biological width?BW?^[5]in the treatment process,such as crown lengthening^[6].Inclusion criteria:1)teeth aged 33⁶5 years old,with subgingival wedge defect,no obvious self-conscious symptoms,and the defect gingival square distance from gingival groove base<0.5mm;2)X-ray showed that the ratio of crown and root of all affected teeth was coordinated,the oral hygiene was good,and there was no systemic disease or allergy history.Exclusion criteria:1)short tooth roots,and the length of clinical crown was greater than that of clinical root;2)those whose general conditions are not suitable for surgery;3)poor compliance.From August 2016 to February 2018,60 patients with subgingival wedge-shaped gingival defects whose gingival fonda was less than 0.5mm were selected,which was not conducive to dental restoration.The 60 affected teeth were divided into two groups:the minimally invasive crown lengthening group?experimental group?and the conventional crown lengthening group?control group?,each with 30 affected teeth.The two groups were prospectively observed for 6 months.Objective To explore the clinical effect of minimally invasive crown lengthening combined with nano-resin in the repair of subgingival wedge defects.Methods From 2016-08 to 2018-02,a total of 60 patients with subgingival wedge-shaped defects reaching the gingival crevicular trench bottom<0.5mm,were randomly assigned to the minimally invasive crown lengthening group?experimental group?and the conventional crown lengthening group?control group?to prospectively observe the clinical efficacy.Record the preoperative and postoperative 8 weeks,six months out diagnosis depth?the probing the depth,PD?,attachment loss?attachment loss,AL?,preoperative and postoperative week,eight weeks and six months of bleeding index?bleeding index,BI?,loose teeth,tooth mobility,MD),postoperative visual analogue scale method?visual analogue scale,VAS?of one,three,seven days.Results Both groups showed improvement after surgery.The postoperative values of PD,AL,MD and VAS in the experimental group were significantly lower than those in the control group?P<0.05?,and there was a positive correlation between AL and MD?P<0.05?.Conclusion Minimally invasive crown lengthening combined with nano-resin in the repair of subgingival wedge defects can achieve a more satisfactory clinical effect.