Analysis And Solution Of Poor Proximal Contact Between Fixed Implant-supported Dental Prostheses And Adjacent Teeth

BackgroundCurrent research suggests the high levels of long-term survival rate of implanted fixed repaire[1,2].The 5-year survival rate of the implants is between 96%and 97%,the 5-year survival rate of the restorations is between 87%and 97%.10-year survival rate of single crown restoration implants is 95%,and the prosthesis survival rate was 89%[2].According to systematic reviews[2-4],the most common mechanical complications of single crown restorations are cemented-retained prosthesis that falls off due to loss of adhesive force,abutment screws loosen and porcelain collapsed.However,in recent years,food impaction caused by poor proximal contact between implant-supported fixeddental prostheses and adjacent teeth has also been considered as one of the common complications.Compared with implant-supported fixed restorations,the incidence of natural tooth prosthesis is low.Poor proximal contact refers to the weakness or of the dental floss passes through the prostheses and adjacent teeth,and the location and area of the contact point are unsatisfactory.Food impaction is defined as three types,the food is introduced into two adjacent tooth spaces by occlusal forces(vertical impaction)or by tongue or cheek muscle strength(horizontal impaction),and the two conditions coexist.Factors associated with food impaction include poor proximal contact,unsatisfied position and area of contact points,borderline ridge defects,filling cusps,and the black triangle due to gingival recession or periodontal disease[6].Some researcher believe that food impaction is significantly associated with poor proximal contact[7,8],but the food impaction is not affected by the filling of the Gingival papilla[7].According to long-term clinical observations,the main cause of patient discomfort is vertical food impaction.Horizontal food impaction has no pressxure on the periodontal tissue,and it is easy to remove the impacted food,so it is called food retention.Food impaction greatly reduces patient satisfaction with prostheses,and increases the risk of dental caries,depth of probing in the periodontium,and leads to progressive loss of alveolar bone,so that proper proximal contact between implant-supported fixeddental prostheses and adjacent teeth is very important to prevent food impaction,tooth movement and other periodontal complications[6,9].Therefore,vertical food impaction caused by poor proximal contact is a question worthy of attention of clinicians.At present,the common clinical method for solving the problem of poor proximal contact between implant-supported fixeddental prostheses and adjacent teeth is to remove the restoration and add porcelain or redo the prostheses.The upper prostheses of the implant is required to be easy retrievability.Screw retention requires technique sensitivity of the surgery,temporary adhesives increased probability of prostheses lost retention,permanent cemented restorations could destory the abutments and implants during demolition.The fracture of the porcelain requires restoration time,multiple visits,and certain costs,causing great inconvenience to the patient.Objection:By investigating patients who have fixed implant restoration,explore the relationship between food impaction and poor proximal contact and the possible causes of this phenomenon.In order to solve the problem of food impaction caused by poor proximal contact of implant-supported fixed restorations,we designed a new type of Mesio-distal adjustable crown(MDA crown)can solve the food impaction caused by poor proximal contact several times.The problem is that the crown must be simple to produce and can be widly used.The patients who participated in the study were regularly visited to observe the restorations and the treatment of food impaction.Material and methods:According to the inclusion and exclusion criteria,a total of 104 patients(56 males and 48 females)with an average age of 59 years old and 104 restorations(166 contacts)were recruited from the Stomatological Hospital of Southern Medical University from 2005 to 2017 and 118 implants were included in this study.Statistical analysis of the incidence of food impaction after implant restorations,and poor proximal contact between implant-supported fixed dental prostheses and adjacent teeth.In this part,SPSS20.0 software was used to analyze and graph the experimental results.Kaplan-Meire method was used to draw the survival curve.Log-rank was used to test the differences between groups.The Cox proportional hazards model was constructed to explore the factors affecting food impaction.P<0.05 was considered statistically significant.In view of the poor proximal contact between implant-supported fixeddental prostheses and adjacent teeth,we designed a prosthesis to solve the problem of food impaction caused by poor proximal contact.Communicating with the technicians of the denture processing factory to improve the design of the MDA crown and the precautions for the production of the denture,and to complete the final denture model to solve the food impaction caused by the high incidence of poor proximal contact.From April 2017 to September 2017,44 patients were treated with MDA crowns,and the minimum observation period was 6 months.There were 44 prostheses,including 20 males(48%)and 22 females(52%).The age ranged from 24 to 77 and the average age was 55 years old.MDA crown design:In the presence of natural teeth on the side(prosthesis near and far),2 types of inlays are reserved when the inner crown is cast.After the porcelain is finished,the material is placed in the cavity with a resin material.If there is a problem of food impaction,the inlay can be removed,the seat can be filled with resin,or the inlay can be repaired.The patient does not need to dismantle the superstructure during treatment.Through follow-up,the restorations was observed,and whether the solution of food impaction problems was convenient and effective.Results:A sample survey was conducted on patients who had completed fixed implant restorations.Of the 104 implants supported by 118 implants,the incidence of food impaction was 57%,and the incidence of poor proximal contact was 57%.Of the 174 contact surfaces between adjacent teeth,65(37%)were found to be in poor proximal contact,and 49(47%)of the mesial contact surfaces have poor proximal contact.The distal contact position accounted for 16(23%)of the total number of distal contacts.When poor proximal contact,food impaction occurred at 3(2%)contact surfaces.In addition to the physiological factors,the restoration of the porcelain ffacture caused the poor proximal contact was 8(13%),and the neighboring natural teeth were loose and there was 21(32%)contact surfaces with poor proximal contact.The manufactured MDA crown is satisfactory in terms of aesthetics and functionality.All the materials used can be completed by a conventional denture processing factory,and the production process is easy to grasp and promote.Among the 44 prostheses of 44 patients who have MDA crown restoration,44 were intact in the follow-up period,6 had food impaction,5 were completely resolved after 1 visit,and the other resolved through 2 follow-up visits.All patients were followed up for 6-10 months,with an average of 7 months.Conclusions:Food impaction caused by poor proximal contact between implant-supported fixeddental prostheses and adjacent teeth is very common,and the rate of progression over time increase continue.Due to the tooth physiological drift,the looseness of adjacent natural teeth and other factors,the contact loss between the implanted fixed restoration and the natural tooth may increase with time,seriously affecting the patient's satisfaction with restorations.It is very important to solve the problem of food impaction caused by the poor proximal contact between implant-supported fixed dental prostheses and adjacent teeth countries many times and cheaply.The design of MDA crown can simply and repeatedly solve the problem of food impaction caused by poor proximal contact between implant-supported fixed dental prostheses and adjacent teeth and guarantee the aesthetic effect of the crown.However,the current observing time is short so it takes longer clinical observation to discover complications and further complete.