ABSTRACT：BACKGROUND：The use of regular-sized dental implants is generally recommended to ensure adequate bone to implantcontact. However，when the width of the edentulous crest is insufficient for the placement of a regular-sizedimplant，the use of a narrow-diameter implant（NDI）should be considered to prevent the need for invasivereconstruction techniques such as grafting procedures. The aim of the present study was to evaluate the clinical effect of narrow diameter implants by observing of narrow diameter implants in the repair of the absentmaxillary central incisors.METHODS： selected 20 patients with narrow diameter space were collected on the column，and all cases of patients with narrow diameter implants for maxillary and mandibular in column implant repair，follow-up 3 months’ observation of the patients before and after surgery，before and after repairmen with CPB values，CPB CP（BC（neighbor）and tooth groove the distance from the crest），which is mainly used to measure the effect of distance on the gingiva papilla on the maxillary incisor in single implant appearance after the repairmen.RESULT：After 3 months，among 20 cases of patients after the healing period，19 cases of patients were dental implant stability，1 patients was slight loosening of the implant，and the success rate was 98.33%，50 patients in 6 months follow-up showed no implant loosening and shedding and inflammatory changes. After surgery and before repair，the average value of CPB variable was in the range of -0.16~0.67mm，and the average value was（0.24 ±0.13）mm，and the difference was statistically significant（t =2.123，P=0.043）.CONCLUSION：The maxillary central incisor dentition defect with narrow diameter implants can significantly meet the aesthetic requirements of patients，and with the maximum use of the original alveolar bone，there are fewer complications. It is suggested the clinical application of narrow diameter implant because of its well clinical effect in the repair of maxillary central incisor.
Keywords：narrow-diameter implants，implant restoration，maxillary central incisor，dentition defect，clinical effect
1. Introduction
The dental implant is a very successfultool in the treatment of partial andcomplete edentulism，making it a popular treatment modality[1，2]. In particularcases of single or multiple tooth loss，preparation of healthy teeth adjacent to theedentulous areas is avoided，and the alveolar boneis preserved with implant restorations[3]. The use of a wide or regular-sized implant（>4.0mm）is generally recommended to ensure sufficientbone to implant contact[4–6]. However，it should bepointed out that a minimum of 1 mm of bonethickness must surround the entire implant surface[7]. In cases of bone atrophy of the long-termedentulous areas or bone loss due to periodontaldiseases，periapical pathologies，and traumatictooth extractions，bone width is usually notadequate for regular-sized implants[8–11]. This isbecause the width of the buccal and lingual bonewalls will be diminished and，in particular，theheight of the buccal socket wall will be reduced[10，11].Placing a regular-sized implant in such situationsmay cause large dehiscences，and thus，a risk ofcomplications and failure[7]. Moreover，the use ofnarrow-diameter implants（NDIs）in alveolar bonewith a limited buccolingual or mesiodistal widthmay prevent the risk of injury to neighboringteeth[7，12]. To overcome the above mentioned andadditional problems related to reduced interdentalspaces due to migration or drifting of the remainingteeth，replacement of mandibular incisors andmaxillary lateral teeth，and narrow denture-bearingareas in edentulous patients，almost all implantmanufacturers have introduced NDIs（diameter<3.75 mm）[4，13–15]. Nevertheless，it has been shownthat implants with wider diameters help to reducemaximum stress values in the bone，are mechanically more resistant，and have higher removaltorque values than NDIs[16–19].
Although NDIs have been available for morethan 10 years，few studies have analyzed the clinicaloutcomes[7，15，16，20，21]. These studies mostly showedsuccess rates similar to those of standard-diameterimplants.
Maxillary central incisors are more common in patients with injury and loss in dentistry. Because of the special position of the maxillary central incisor，located in the middle of the mouth，and slightly prominent，making it more vulnerable to damage，and the impact on people's face after injury is also the largest. Therefore，it is a widely studied problem that choose what kind of surgical treatment of maxillary central incisor missing. In this study，we had do some research about what kind of implant diameter we’d better use just after the maxillary incisor，and through the maxillary incisor extraction in 20 cases of patients with defect of column，using a narrow diameter implant restoration，observe the treatment complications and aesthetic effects，to evaluate the clinical effect of narrow diameter implant.
2.Materials and Methods
2.1 general information20 cases of patients with defect of incisor extraction column of University Zhongnan Hospital Department of Stomatology in recent three years were extracted，including 11males，9 females，who aged 18 to 50 years old，with the average（34.12 ±5.27）years old，among which unilateral dentition defect were 12 cases，bilateral were 8 cases. Inclusion criteria：（1）periodontal health or patients with periodontitis after treatment tend to be normal；（2）alveolar bone lip palate thickness of 4.5 to 6 mm；（3）the edentulous space of alveolar ridge and adjacent teeth far side of alveolar crest height gap；（4）patients who smoke less than 5 per day. Exclusion criteria：（1）patients with severe organ dysfunction，endocrine diseases，malignant tumors or other diseases；（2）the patient's condition is not suitable for dental implant surgery，etc..
2.2 research method Physicians who are to check and design asked patients the necessary systemic and oral examination，and by X ray to understand the tooth loss area of sclerotin and bone mass，to determine whether patients suitable for dental implants. And in accordance with the selection of patients to determine the treatment plan，firstly embed the implants under local anesthesia，and take out stitches1 week after suture. If the implant bone graft，bone healing is prolonged；healing abutment connection when the implant combined with the jaw，the implants connected to a healing abutment，the soft tissue in the 3W forming；complete the repair when the soft tissue cuff after the formation of the doctor with a permanent abutment replacement healing abutment，impression，the design of the restoration of teeth，tooth crown or bridge well，then can wear the implant supported teeth.
The implant and jaw bone formation with general in 4 ~ 6 months after surgery，with a special instrument of implant in implantation under local anesthesia in the corresponding gums cut 1 small mouth，the implant was exposed after the installation of upper gum pile. We can repair modulus，make planting tray and dentures7 ~ 10d after the two stage operation.
2.3 Research IndicatorsThe difference of CPB value before and after the operation，before and after the repair for 3 months was observed. CPB was used to measure the distance between the adjacent points（contact point，CP）and the crest of alveolar ridge（alveolar bone crest，BC），and to evaluate the effect of the distance on the appearance of the gingival papilla after implant restoration.
2.4 statistical methodsUsing SPSS 13 statistical analysis software，the measurement data to "x ± s"，before and after treatment and before and after repair using paired t test. The difference of P<0.05 was statistically significant.
3. Results
20 patients after a period of 3 months of healing，there were 19 cases of dental implant stability，and one patient with a slight loosening，accounting for 1.77%，and the planting success rate is 98.33%. 19 patients were followed up for 6 months without loosening，shedding and inflammation. 19 patients in a small diameter is dentition defect before and after operation，the CPB value is（0.23±0.13）mm，before and after repair，the CPB value is（0.08 ±0.02）mm，andbefore and 3 months after repairment，the CPB value is（0.02±0.01）mm，which showed no difference statistical significance（t=2.342，P= 0.074）. And after the operation and before the repairmen，the average value of CPBrange from -0.16 mm to 0.67 mm，the average value is（0.24±0.13）mm，the difference was statistically significant（t=2.123，P=0.043）.
4.Discussion
4.1 maxillary central incisor tooth defectThe location and the number of missing teeth are different[21]. The method of artificial replacement of material is the main way to restore the morphology and physiological function of missing teeth[22]. The repair methods include fixed denture，removable partial denture，removable partial denture，implant denture，etc. And each method has its specific scope of application. The central incisor dentition defect is the main area of the dental aesthetic defects，because it not only seriously affects the aesthetic view [23]，but also is difficult to treat，so it is the focus and the difficulty of the study.
4.2 The application narrow diameter implant The selection of the implant is very important，and the main index is diameter and crudeness or fineness and so on[24]. Bone regeneration and autologous bone graft is the massive dental aesthetics，guided bone regeneration and autologous bone block graft technique is lack of aesthetic bone volume before planting commonly used technique of bone augmentation [25-27]. It should be pointed out that a clarification on nomenclature may need to be addressed by the field of dental implantology concerning mini，narrow，standard，or wide diameter implants. They seem to be blending together in diameter specifications. Although some authors believe an implant with a diameter <3.75 or 4 mm is narrow or small，others think these implants require a minimum mesiodistal space of 6 to 6.5 mm to allowadequate implant to tooth distance and call implants with a diameter <3 mm NDIs. However，implant designs with diameters below 3 mm have been introduced into the market under the banner of ‘‘mini implants.’’ In a few published studies，small- or narrow-diameter implants were classifiedin a specific dimension range. Comfort et al 20 regarded implants of 3.0–3.3 mm in diameter as small；whereas implants with a diameter of 3.0 to3.4 mm were called narrow by Davarpanah et al. Inall of these studies，implants with a diameter of 3.75 or 4.0mm were regarded as regular-sized implants.The implants that we evaluated were 3.3 to 3.5 in diameter and were all below the regular size；thus，calling them narrow was deemed appropriate in the present study. As the smaller-diameter implants known as mini implants were not used in this study，the results cannot be applied to these mini implants. Through the analysis of 20 cases of patients with dentition defects，the application of CPB evaluation index，evaluation of the effect of the transplantation，the results showed that 20 cases of patients after 3 months after the healing period，19 cases of patients with dental implant stability，1 of the patients had slightly loose，the success rate of implant was 98.33%. 19 patients in a narrow diameter before and after operation，the CPB value before and after repair，the CPB value before and 3 months after repairmen had no significant difference. And after surgery and before the restoration，the difference ofthe CPB was statistically significant. And we can consider that the CPB valuebefore the repairmen is significantly higher than that after surgery.
5. Conclusion
The anatomic structure of the maxillary central incisor is the most complicated，and the implant is relatively difficult. There have been different views on the selection of implant diameter. The diameter of the maxillary central incisor implant is about 4mm，and we adjust the specific size according to the specific situation of patients[28]. Narrow diameter implants generally refers to the diameter of implants which are 3.5mm and below [29]. The wide implant has a large load capacity，but has some adverse effects on the growth of the teeth and the osseointegration of the implant.
The use of narrow diameter implants for the repair of the maxillary central incisors has not been recognized since the narrow diameter implant may not has as large as the load intensity，and itcan not meet the requirement of the function of the maxillary central incisor [30]. But this test showed that the occlusal strength of narrow diameter implants were not worse than conventional implants，with narrow diameter grown in the alveolar bone condition of maxillary central incisor in the absence of body to effectively reduce the probability of planting body rough surface exposed，reduced the possibility of alveolar bone continuasilly lossing，and lay the foundation of the stability for osseointegration in the long-term. At the same time，due to occlusal load bearing incisor was significantly lower than the posterior teeth，in the premise to improve the blending，implant，abutment and screw fracture associated with implant diameter of mechanical complications were significantly increased. The results of this study showed that narrow diameter implants haswell clinical effects in the repair of maxillary central incisor and the occlusal satisfaction，appearance satisfaction，comfort satisfaction and etc. can meet the requirement， and the complications are less.
To sum up，the clinical effect of narrow diameter implant for the repair of maxillary central incisor missing is good，it is recommended to
be used in clinic.
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论文作者:Marwa Alkhameri Jiangang Chen，
论文发表刊物:《航空军医》2017年第4期
论文发表时间:2017/4/19
标签：UNDERSTAND论文; area论文; sclerotin论文; ray论文; systemic论文; oral论文; examination论文; 《航空军医》2017年第4期论文;