Dental implant placement on alveolar bone grafted patients after cleft lip and palate reconstructive surgery

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Ministry of Education & Training Ministry of National Defense 108 Institute of Clinical Medical & Pharmaceutical Sciences  VO VAN NHAN DENTAL IMPLANT PLACEMENT ON ALVEOLAR BONE GRAFTED PATIENTS AFTER CLEFT LIP AND PALATE RESCONTRUCTIVE SURGERY Specialty: Odonto - Stomatology Code: 62.72.06.01 PH.D THESIS SUMMARY Hanoi - 2014 THE RESEARCH WAS FINISHED AT 108 INSTITUTE OF CLINICAL MEDICAL & PHARMACEUTICAL SCIENCES Full name of scientific instructors: 1. Assoc.Prof. Ph.D. Le Van Son 2. Ph.D. TaAnh Tuan Judge 1:Assoc.Prof. Ph.D. Trinh DinhHai Judge 2: Ph.D. Le Hung Judge 3: Prof. Ph.D. Le GiaVinh The thesis will be defended before the Thesis Assessment Council at Institute level At , date month year Be able to search the thesis at: 1. National library 2. 108 Institute of Clinical Medical & Pharmaceutical Sciences Library 1 I. RATIONALE OF THE SUBJECT Cleft lip and palate (CLP) is the most frequently reported congenital birth defect in the cranio-maxilo-facial field. According to WHO, the overall incidence of cleft lip and palate is reported around 1/500 live births [138]. This incidence is different depending on regions and races:it’s low in the black and high in Japanese, Chinese and Indian-American. In Vietnam, this incidence is about 1/709 to 1/1000 [2], [7]. Around the world, some clinicians successfully applied implant treatment for cleft lip and palate patients like Verdi (1991) [139], Kearns (1997) [68],…. In Vietnam, the research on cleft lip and palate patients mainly assess epidemiology and cleft lip - palate closing technique [1], [3], [4], [5], [7], a few studies were takenabout alveolar bone graft such as study of Nguyen Manh Ha (2009) [6], or implant placement in normal patients without defects of Ta Anh Tuan (2007) [8]. Thus, the implant placement on the grafted bone and implant prosthetic on CLP patient is the problem that has not been studied comprehensively in Vietnam. Meanwhile, the demand for treatment is huge since most CLP patients have not had bone grafts and dental restorations as of yet. With the desire to implement the implant technique for CLP patients in Vietnam and perform a systematic scientific research, we conducted the thesis "Dental implant placement on alveolar bone grafted patients after cleft lip and palate reconstructive surgery". II. RESEARCH OBJECTIVES 1. Evaluate jaw bone condition after alveolar cleft bone graft 2. Evaluate the success of implant treatment. 2 III. MEANING The thesis provides a new treatment method for patients with cleft lip and palate defect, not only torecoverthe function but also to meet the aesthetic demand helping patients communicate confidently for community integration. IV. THESIS STRUCTURE The thesis consists of 121 pages, not including appendices and references. The contents of the thesis are: Introduction (2 pages), Literature review (31 pages), Research subjects and method (29 pages), Research results (20 pages), Discussion (36 pages), Conclusion (2 pages), Recommendations (1 page). The thesis has 23 tables, 4 diagrams, 12 charts, 69 pictures, 144 references (9 Vietnamese, English 135). Chapter 1: LITERATURE REVIEW 1.1. CLEFT LIP AND PALATE Cleft lip and palate are birth defects causing deficiency and deformities of the nose, lips, palate that affects the formation of unerupted tooth, teeth eruption, malocclusion, mastication, distortion of the mesial floor and inferior floor of the facial, pronunciation, the aesthetic and psychological diseases [94], [65]. Therefore, those who suffer from this malformation always feel inferior andcan feel distance from community. The treatment of CLP defects is a long process from the child still in the womb to anadult with the cooperation of many experts and various techniques including psychological counselling, primary lip and palate repair surgery, alveolar cleft bone graft surgery, orthodontic treatment, dental restorations, ... [101], [106]. 3 1.2. ALVEOLAR CLEFT BONE GRAFT 1.2.1. The necessity of alveolar cleft bone graft Alveolar cleft bone graftingprovides room for orthodontic movement of the teeth in the position of #3 and #2 (canine and lateral incisor) to erupt into the cleft or for dental prosthesis, maintain bony support of teeth adjacent to the cleft, preserve the health of the arch and facilitates closing of the fistula in the secondary bone grafting [138]. 1.2.2. Flap preparation forgrafted recipient Flap designs in alveolar cleft bone graft surgery are extremely important to determine the success of the surgical procedure as it provides adequate soft tissue for the closure over the bone graft without flap tension and dehiscence. There are many flap design techniques such as thelateral sliding flap, the oblique sliding flap, the buccal finger flap, the nasal lining flap and the palatal flap [18].The flap designs can be used by single or multiple techniques, depending on the clinical situation for optimaltensionfree closure. 1.2.3. The choice of donor site for graft material Autogenous bone can be taken from many different sourcesin which the tibia is first used, followed by iliac crest, ribs, chin and calvarial bone (SindetPerdersent and Enermark 1988) [116]. Some authors have done a lot of research in order to replace the autogenousbone material in alveolar bone grafting,such as with demineralized freeze-dried bone combined with iliac cancellous bone of Steven (2009) [121], β Tricalxium-phospate (TCP) of Ruiter (2012) [107] or BMP-2 (bone protein) of Dickinson (2008) [39] but studies using these materials is still not advancedand is 4 not commonly applied. Therefore,autogenousgrafted bone is still considered as the golden standard for graft material of alveolar cleft recovery.Ananth’s research (2005) summarized 110 centers with 240 CLP surgical teams, which showed iliac crest bone is still the most popularmaterial used by 83% [19]. 1.2.4. Techniques of placing grafted bone There are many techniques in placing the grafted bone in the cleft such as iliac crest cancellous bone graft [46], iliac crest bone block graft [31], autogenous bone graftwithartificial membrane barriers covering graft material [100], the use of a cortex bone plate (CBP) along the lining of thepalatal suture line[85] and lateral corticalbone plates from the symphysis[127]. But so far, these techniqueshave not been commonly used in alveolar cleft bone grafting. 1.2.5. Evaluation methods of bone graft result 1.2.5.1. Means of evaluation Some authors evaluate the results of bone graft by histology [60] but the most popular is still by computed tomography, including periapicalradiography, occlusalradiography, panoramic radiography, conventional CT and Cone Beam CT. The results of alveolar cleft bone graft was previously mainlyassessed by periapicalradiography and occlusalradiography[46], [54], [55], [72], [81] but these films did not measure the buccal-lingual distance of the graft [77]. Therefore, Cone Beam CT today has become popular and useful in assessing changes in volume and size in 3-dimension[59], [137]. 1.2.5.2. Evaluation scale 5 Nowadays, for the assessment of the alveolar bone graft outcome, most of thestudies usethe combination of two-dimensional film (periapicalradiography and occlusalradiography) through the evaluation scale of the bone bridge formation in the cleftand CTCone Beam to examine the 3dimensional size or volume of the Figure 1.16:Enermark scale[42] graft [24], [26], [61], [79], [128], [137]. Several scales are applied such asEnermarkscale (1987) [42], Berglandscale (1986) [24] using periapical radiographyand Kindelanscale (1997) [71] using occusal radiographyto assess the bone heightbetween the teeth in the cleft areas, successful results was obtained when more than 50% bone fill in the cleft areas (Figure 1.16). Thesescales are popular because it is easy to apply in comparison with Long scale [81] and Witherow scale [140]. 1.3. DENTAL IMPLANT Osseointegratedimplant that was developed by professor Branemark in the 1960s has now becomeconventional treatment method to restore the missing teeth as well as congenital teeth deficiency in CLP patients. In 1991, Verdi [139] reported a first case of successful alveolar bone grafting and implant treatment, then followed by some reports of implant treatment in similar situation as Fukuda (1998) [50], Kearns (1997) [68], Lilja (1998) [79], Takahashi [130], [131], ... Implants have the supported fixationcomponent whichauthors have developed many flexible solutions for implant prosthesesfor various and complex situations of CLP patients after alveolar cleft bone grafting. However, most 6 of the above studies have evaluated the success of implant osseointegration, not the aesthetic of implant prostheses. Chapter 2: RESEARCH OBJECTS AND METHOD 1.1. Research subject - Patient selection criteria: Patients over 15 years old, in good health for endotracheal anesthesia, already has had palatoplasty, complete unilateral alveolar cleft, lack of permanent tooth germ in the cleft andhas not had any alveolar cleft bone graft. - Elimination criteria: No alveolar cleft, no unilateral or bilateral alveolar cleft.Patientswho disagree to participate in the research. 1.2. Research method 1.2.1. Research design: This thesis useda prospective uncontrolled clinical trial method to evaluate alveolar cleft bone graft outcomes and implant success. Sample size: 32 patients by the averageestimating formula. 1.2.2. Research time:August, 2010 to February, 2014. 1.2.3. Research procedure: Firstly, patient information was collectedwith a case history form. After orthodontic and general dental treatment, alveolar cleft bone grafting surgery was conducted with the technique of 2 iliac corticocancellousbone block autograft. 4 to 6 months later, the implant placement was performed; 6 months later, prostheses on the implant was executed.There was continued follow-up 15 and 18 months after the alveolar cleft bone grafting. 1.3. Surgical procedure 1.3.1. Iliac bone block harvesting surgery A5cm incision over the superior iliac crestwas made 1 cm from anterior superior iliac spine to prevent damage of the lateral femoral cutaneous nerves. Thesubcuticular structure and 7 mucoperiosteumwas infiltrated and then dissection of the periosteumwas carried out to expose iliac bone. Ultrasonic piezotome device was used to make 4 cuts: the first cut of 4cm on the superior iliac crest away from the cortical bone in the abdominal cavity of 0.5cm, the second and the third cuts with the length of 2cm were perpendicular to the first cut. The fourth cut was perpendicular to the second and the third cuts. These four cuts created a rectangle. A chisel was used to harvest the bone block including the cortical and cancellous bone with the size of 4 x 2 x 0.5cm3. Afterthat, hemostatic sponge was placed and 2 layer sutures were used:periosteum suture and subcuticular suture. The bone blocks were kept in a small stainless steel cup in saline for moisture preservation. 1.3.2. Alveolar cleft bone graft surgery: Flap design: The incision began at the edge of the cleft and wentover the cleft’s perimeter,divided the cleft into 2 parts, then went down to the alveolar crest, moved to the two sides ofthe teeth’s neck next to the cleft and thencontinued to follow the gingival contours to the distalof tooth #4 or #5 and upwardto the vestibularforming avertical incision. At the top of the vertical line, an incision was made with the vertical line ofangle 120° to easily slidethe flap to the lateral and downwardposition (Figure 2.28). After that, from the incision on the alveolar crest that stayed closely to the neck (lateral) of the two teeth adjacent to the cleft, the incision was continued along the gingival sulcus on the labial side to the teeth at the two sides of the cleft. The nasal flap closure began with the suture from the buccal to the labial at one side of the flap edge, then the dissection was 8 continued from the labial to the buccal at the contralateral flap edge. Finally, the knot was made (Figure 2.29). Based on the bone grafting technique of two lateral cortical bone plates from the symphysisby Tadashi Mikoya(2010) [127], we introduced two iliac corticocancellousblock grafting techniques in this study with the technical steps as follows: Step 1: Placement of cortical bone plate on the labial (nasal) aspects of the alveolar process defect: The iliac bone block was cut into 2 blocks. The first corticocancellous block with the size of the cleft size was placed on the sutured nasal mucoperiosteum (Figure 2.30). The cancellous bone was added on the plate until it nearly filled the cleft (Figure 2.31) Figure 2.30: The bone block on the nasal lining Figure 2.28: The incision for flap design on the vestibular Figure 2.29: Nasal flap closure Figure 2.32: Theby bone block onbone the vestibular was secured by2.33: screws Figure 2.31: The cleftwas nearly filled cancellous Figure Wound closure Step 2: The second corticocancellous block with a larger size than the cleft was placed on the grafted cancellous bone covering the whole cleft and secured by screws for a tight fixation(Figure 2.32). 9 Step 3: The wound closure: the palatal mucoperiosteumandthe vestibular mucoperiosteum wereclosedby the suture on the alveolar crest. Vestibular mucoperiosteum wassutured onboth sides of the cleftfrom the ridge of the alveolar crest towards thevestibular recess. The suture was continuedto recover the sulcus gingiva of the tooth from the cleft area. Finally, mucosa closure was made with the vertical tension-freeincision from the vestibular recess towards thealveolar crest (Figure 2.33). 1.3.3. Implant placement surgery and implant prosthodontics + Implant placement in the aesthetic zone [29]: Using implant surgical guide to ensure: Implant direction passes the occlusal edge of the further prostheses;In the buccal-lingual dimension, the buccal side of the implant is 2mm from the buccal side of the cortex;In the apical-coronal dimension, the implant shoulderis a distance of 3mm from the free gingival margin;In the mesial-distal dimension, the implant has a distance of at least 1.5mm from the next root. + Prosthodontics: 6 months after the implant placement, secondary surgery of gum opening was carried outfor inserting the healing screws, then 3 weeks later, the impression is done for the prosthodontics. 1.4. Assessment criteria 1.4.1. Soft tissue condition at the recipient site - Good: pink mucosa, dry, tight and healing scar - Average: dehiscence but nograftexposure. - Bad: infection,dehiscenceorbone graftexposure. 1.4.2. Oronasal fistula 10 - Closed: Clinical examination showed the fistula was closed. - Unclosed: Clinical examination showed the fistula still exists. 1.4.3. Assessment of alveolar bone graft - Assessment of bone bridge formation by periapicalradiography Enermark scale was used for assessing bone formation in the cleft[42] according to 4 levels: • Type I: 75% - 100% bone recovery compared to the initial bone graft site. • Type II: 75% - 50% bone recovery compared to the initial bone graft site. • Type III: 25% - 50% bone recovery compared to the initial bone graft site. • Type IV: 0% -25% bone recovery compared to the initial bone graft site Type I and Type II are considered successful. Type III is partial failure. Type IV is completely failure. - Assessment of bone grafting result by CT Cone Beam • The apical-coronal distance: marked as d, is measured from the lowest point and the highest point of the grafted bone on CT slices through the adiaphanouslocation axis on the surgical guide. • The buccal-lingual distance: marked as r, is the average of the apical-coronal distance of 1/3 superior (a), of 1/3 mesial (b) and of 1/3 inferior (c), r = (a+b+c)/3. 11 • FollowingRenouard’s standard (1999): if the apical-coronal distance is at least 7mm and the buccal-lingual distance is at least 4mm then there isenable for implant placement [47] 1.4.4. Assessment of implant placement Assessment of the success of implant oseointegration by Misch’s criteria (2008) [89] included 4 levels: o Success: if no pain in function, no clinical mobility is noted, less than 2.0 mm of radiographicallycrestal bone loss is observed compared with the implant insertion surgery, no history of exudate. o Satisfactory survival: if they are stable, no observable pain and mobility in function, radiographic crestal bone loss is between 2.0 and 4.0 mm from the implant insertion. o Compromised survival: with no pain in function, no mobility, greater than 4mm radiographic crestal bone loss but less than 50% from around the implant, more than 7mm of probing depths, often accompanied with bleeding. o Failure: if any of these conditions are presented: pain in function, mobility, more than ½ implant length of bone loss, uncontrolled exudate, or has been surgically removed. - Assessment of the implant prosthesis’saesthetic: + Following pink esthetic score (PES) and white esthetic score (WES) based on Belser’s standard (2009) [23]: The pink esthetic score assesses the soft tissue condition around the implant through 5 factors compared to the contralateral tooth: mesial papilla, distal papilla, curvature of the facial mucosa, level of the facial mucosa, and root convexity, soft tissue color. White esthetic score presents the esthetic of the implant restoration with 5 parameters in comparison with the contralateral reference tooth: general tooth 12 form, volume of the clinical crown; color, surface texture and other characterization. A maximum total score WES and PES of more than 12 was set for being esthetically successful, a score of 12 for clinical acceptance and a score of under 12 for estheticalfailure. + Assessment of the degree ofpatient satisfaction by the score of 1 to 9 with a score of 1, 2, 3 for unsatisfactory, a score of 4, 5, 6 for satisfactory and a score of 7, 8, 9 for above satisfactory [43]. Chapter 3: RESEARCH RESULTS 3.1. Clinical characteristics of the study sample - Total of 32 patients with the average age of 20.2 (15-29), 23 females and 9 males in which 23 had left-side UCPL and 9 had right-side UCLP. 100% of patients presented with an oronasal fistulaand misalignment. Therefore, all patients required orthodontic treatment with the average time of 12.5 months for treatment. - The occlusion of Angle Class I was found in 53.1% patients, Angle Class III in 28.1% patients, the occlusion of cross bite, edge to edge or open bite in the anterior but Angle class I in the posterior was reported in 18.7%. Each patient had 9.8 decay on average. 3.2. Result of alveolar bone graft 3.2.1.Mucosa condition of the recipient At the follow-up 7 days postoperatively, 29 cases (90.6%) reported good healing. A wound dehiscence occurred in three patients (9.4%) resulting in a partial loss of bone, but the region 13 healed uneventfully after exfoliation of small bone fragments. After 4 to 6 months, 100% of cases showed good healing. 3.2.2.Result of alveolar bone graft 3.2.2.1.Result of bone formation usingEnermark scale In the follow-up 4 to 6 months after the bone graft surgery, the bone formation type I was 90.6% and type III was 9.4%. There was no change after 12 and 15 months. After 18 months postoperatively, 1 patient appeared bone resorptionwhich dropped from type I to type II. However, type Iand type II are considered as successful by Enermark, so the total success rate of the graft was 90.6% (Table 3.30). Bone bridge formation in the cleft at the point of 18 months compared with the point of 6, 12 and 15 months showed no statistically significant differences (p<0,05). Thus, implant placement can limit bone resorption. Table 3.30: Result of bone formation at 6, 12, 15 and 18 monthsafter alveolar bone graft (n=32) Bone bridge level Point of Total times I II III IV 4-6 29 0 3 0 32 months (90.6%) 12 months 29 0 32 0 32 3 32 (9.4%) 0 (90.6%) 15 months 29 (9.4%) 0 (90.6%) 18 months p= 0.764 3 3 (9.4%) 28 1 (87.5%) (3.1%) 0 (9.4%) 14 3.2.2.2. Result of bone formation using CT Cone Beam On axial CT at 6 months postoperatively, the mean apicalcoronal distance of 11.4.0±2.4 mm and the mean buccal-lingual distance of 6.1±1.0mm was reported. According to Renouard’s standard [47], 29 of 32 alveolar clefts (90.6%) displayed thebone bridge formation enable for implant placement. 3 clefts (9.4%)showed insufficient bone for implant placement which indicated fixed bridge restorations. 3.3. Result of implant placement 9,4%% - Total of 32 implants were placed, of which 31 implants were 0%% of size 3.8 x 10mm and 1 implant was 3.8 x 12mm. Of 32 patients, 3 patients had 2 implants placed, 26 patients had 1 implant placed. - Initial implant stability: over 35N/cm2in 2 12.4% of 2 implants,20-35 N/cm in 43.8%and 15-20N/cm in43.8%. - Additional bone graft during implant placement were performed in all 32 patients, in which 90.6% usedcancellous particulate bone graft and 9.4% used ring bone and cancellous particulate bone graft. 3.3.1. Result of implant osseointegration Table 3.31: Result of implant osseointegration at 12, 15 and 18 months after alveolar bone (n=32) Point of times Post Post bone implan graft t surger surger y y Results on implant osseointegration Total Succes s Satisfact- Compro- ory mised survival survival number Failure of implant 15 12 6 32 0 months month (100%) 0 0 32 (100%) s 15 9 32 0 months month (100%) 0 0 32 (100%) s 18 12 31 1 (3.1%) months month (96.9% s ) 0 0 32 (100%) p=0.999 After 12 months follow-up,100% implants were successful and therewas no change after 15 months follow-up. However, after 18 months, 96.9% (31 implants) were successful, 3.1%(1 implant) appearingwith 2mm bone loss making it become satisfactory survival, no implant failure. The total survival of implants in good function were still 100%. The survival rate at the point of 12 and 15 months had no significant difference compared to the point of 18 months (p<0.05). 3.3.2. + Esthetic result of the prostheses on implant Esthetic result followed pink esthetic score (PES) and white esthetic score (WES) based on Belser’s standard (2009) [23]: Table 3.32: Esthetic resultof prostheses on implant at9 and 12 monthsafter implant placement(n=32) Point of times Esthetic result of prostheses on implant Post Post Esthetical Clinical Esthetical bone implan success acceptance failure Total 16 graft surgery t surger y 15 9 18 5 9 32 months months (56.3%) (15.6%) (28.1%) (100%) 18 12 18 5 9 32 months months (56.3%) (15.6%) (28.1%) (100%) In the follow up of 9 and 12 months after implant placement, 18 implant prostheses (56.3%) were esthetical success, 5 prostheses (15.6%) were clinical acceptableand 9prostheses (28.1%) were estheticalfailure (Table 3.32). - Result of degree of patient satisfaction of the prostheses on implant: In the follow up of 9 and 12 months after implant placement, 21 patients (72.4%) were above satisfied with their prostheses, 8 patients (27.6%) satisfied and no patients disappointedwith their prostheses on implants (Table 3.33) Table 3.33: Result of the degree of patient satisfactionof the prostheses on implantafter9 and 12 months after implant placement (n=29). Point of time Post bone graft surgery Post implant surgery Patient satisfaction of the prostheses on implant Above satisfied Satisfied 15 9 21 8 months months (72.4%) (27.6%) Total Unsatis -fied 0 29 (100%) 17 18 12 21 8 months months (72.4%) (27.6%) 29 0 (100%) Chapter 4: DISCUSSION 4.1. The characteristics of the study sample In our study, all 32 patients presentedwith teeth around the cleft misalignment. The occlusion Class III Angle was 28.1% while Class III Angle in normal patients without defects in Dong KhacTham’sstudy was 21.7% [9]. Thus, patients with Angle Class III in our study wassignificantlyhigher than patients without defects (p <0.05). This rate was suitable with Posnick’sstudy (2000) [105]. All patients were treated orthodontic for aligning and making suitable horizontal spaces forfuture prostheses, facilitating flapdesign, flapdissection and flap closure. It also helpsplacing, fixing the graft, determining the volume of bone graft easily as well as the prognosis of the location and orientation of the implant that fit the future prostheses. Furthermore, orthodontic treatment was continued after bone graft surgery that is recommended bya lot of authors as the traction on bone graft will help stimulate the graft’s development (Turvey 1984 [136]). Each patient had 9.8 decays on average and the DMFT Index (Decayed, Missing and Filled Teeth)was 10.5 with no significantly difference (p=0.388> 0.05), whichmeans the subject had not had oral treatment before. 12 patients (37.5%)presentedwith residual tooth in the cleft area. Jia (2006) [64] said that poor oral hygiene often leads to infection, complications and dehiscence after bone graft surgery. To prevent the above complications, all patients received dental treatments, 18 gum treatment and oral hygiene instructions in the treatment process. Residual teeth in 12 cases were extracted at least 2 months before the bone graft surgery to ensure there wasmature gum tissue in the extraction area making better condition for flap closure. 4.2. Timing and purpose of the alveolar bone graft In our study, all patients receivedintermediate secondary bone grafting in the age of over 16 years with the purpose of implant restoration. However, according toDempf’sresearch [36], the alveolar ridge height after intermediate secondary bone graftingwas reported be lower than after late secondary bone grafting (tertiary). This was a challenge we had to face in this study becauseinsufficient bone height would affect the implant stability and the restorations’ aesthetic [36]. Therefore, to overcome this difficulty, we performed additional bone grafts for all cases in implant placement. 4.3. The technique of the alveolar bone graft Based on the technique of a cortex bone plate (CBP) along the lining of the palatal suture line [85], especially lateral cortical bone plates from the symphysis [127], we have modifieda two iliac corticocancellous block graftin alveolar bone grafting. With this new technique, screws were used to fix the bone graft in the vestibular side. Compared with Tadashi’s technique, the symphisis cortical plates are just inserted on the cleft, while according to Buser (2009), the fixation of the graft is definitely an important factor for the successof bone grafting techniques [28]. In the technique of two iliac corticocancellous blocks, we combined the rigid mechanical properties of cortical bone that limit bone resorption and easily obtain the implant initial stability
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