Immediately loaded single unit dental implants: A clinical study

Abstract

INTRODUCTION Missing teeth in aesthetic region has affected psychology of mankind. Contemporary dentistry today offers two distinct solutions to address the problem of partial edentulous state in the form of removable and fixed partial dentures. A removable prosthesis is one that can be removed and inserted by the user at his will and discretion. Though it is flexible, it has its own inherent drawbacks, such as difficulty in speech, altered taste perception, and irritation to denture supporting tissues.[1] Fixed prosthesis overcomes several problems posed by removable prosthesis, but they too are accompanied by several drawbacks, the principal drawbacks being, for replacement of particular tooth/teeth, the crowns of adjacent teeth have to be cut and prepared to serve as abutments. In this way, healthy tooth structure is sacrificed for the sake of replacing a missing tooth. In view of all these problems, a third modality of tooth replacement called the dental implant was brought into existence, after the serendipitous discovery of the phenomenon of osseointegration by Professor Branemark in 1952. With the better understanding of biocompatibility of titanium and effective osseointegration achieved by hydroxyapatite plasma coated surface, implant therapy has reached new frontiers. The science of dental implantology today has become highly evolved, and today it is regarded as a highly effective and predictable modality of tooth replacement.[2] By traditional protocols, the dental implant, once placed in bone, was submerged under the mucosa and left for 3–6 months to allow the implant to osseointegrate into the surrounding bone. During this phase, the patient was advised to wear an interim partial denture in the existing space. Later in the second stage of surgery, the abutment was attached to the implant, and only after adequate healing of soft tissues, the final prosthesis was placed. For many individuals, this way of working may be a psychologically traumatic experience. A need has been felt to develop the routine “implant protocols,” decreasing or even eliminating the healing periods before loading inserted implants.Consequently, creation of fixed implant supported prostheses via protocols for either immediate (within 72 hrs) and early implant loading (within one to a few weeks of healing) have gradually become available during later years as additional concepts, aiming at reducing the treatment time and treatment costs. This is a totally new way of working in comparison to routine “protocols.” The new technique offers several advantages, including increased masticatory function, minimized uncontrolled transmucosal loading through cross-arch stabilization, improvement of psychological well-being, and reduction in treatment time. The new immediate loading approach, therefore, seems to be a good alternative for treatment of the aforementioned group of patients.[3] Therefore, this study was conducted to evaluate the performance of implants subjected to load immediately after placement. This is accomplished under the following headings: To assess osseointegration at regular interval to assess implant stability To assess soft tissue changes surrounding implant after immediate loading To assess marginal bone level changes in the follow-up examinations MATERIALS AND METHODS A total of 24 partially edentulous patients reporting to Government Dental College, Patna, Bihar, India, desiring replacement of missing teeth were selected for the study, if they satisfied the sampling criteria. In this study, 24 single tooth implants were placed in 24 partially edentulous patients. For the study, the edentulous spaces in the aesthetic zone (i.e., the anterior maxilla, consisting of the maxillary incisors, canines, and premolars) are considered. Patient selection is carried out based on age and sex. Inclusion criteria consisted of the following: One or more missing teeth in the aesthetic zone (upper and lower incisors, canines and premolars) were included After extraction, adequately healed and remodeled ridge included Patients with absence of any periodontal problems in adjacent teeth Patients with supra-eruption of opposite tooth Exclusion criteria included the following: Patients with a habit of smoking Patients with a medically compromising conditions, which prohibit implant surgery, such as stroke, recent infarction, severe bleeding disorders, diabetes, osteoporosis, and cancer Patients with a history of bruxism Patients with implant with a torque of more than 35 Nm was not attained; that implant was not selected for immediate loading, and they were excluded from the study Pre- and postoperative were assessed by clinical and radiographic means. It included clinical photographs, study models, orthopantomograph (OPG), and intraoral periapical (IOPA) radiographs. A 1-year follow-up was carried out for 1 year for all subjects. Titanium plasma coated root form dental implant Implants belonging to the Uniti, manufactured by Equinox Medical Technologies B.V., Zeist, Holland, were used in the study. Corticocancellous design implants were used. The shape of the implants was based on the biologic root form concept. Available in various size configurations of diameters 3.3, 3.7, 4.3, 5.3, and 6.0 mm and lengths 10, 13, and 15 mm, the size selection was done according to the manufacturer’s recommendations. The design of the threads of the implant provided the property of self tapping to the implant. These threads have two different shapes (cortical, with a depth of 0.1 mm, and cancellous, with a depth of 0.35 mm), to one continuous pitch of 0.9 mm. The surface of the implant was produced using a water-soluble blast medium that is completely dissolved and removed. This surface has been described by the manufacturer as an osteoconductive, high porosity surface with micropores of 1–5 microns. The transition from the roughened surface to the prosthetic table is a 1-mm highly polished collar. This is said to allow for predictable soft tissue integration by means of a hemidesmosomal attachment, and facilitates oral hygiene. The implant is secured to the abutment by means of a screw, locking the abutment to the implant with a twin hexagon internal connection. The surgical tray is laid out in an autoclavable container, and sequenced with all color-coded drills and stoppers. The standard diameters of the system are D.3.3, D3.7, and D4.3 mm. The manufacturer claims this implant system as suitable for use in delayed loading, immediate placement, and immediate loading situations.[4] A complete case history was taken making use of a standard case history form, and subjects were selected who meet inclusion criteria. Local examination was done to rule out healing status of extraction socket, presence of periodontal problems, jaw opening, and presence of any pathology at the proposed implant site. Preoperative and postoperative photographic records of the edentulous space were maintained [Figure 1].Figure 1: Preoperative photograph and radiographRadiological investigations such as OPG and IOPA The preoperative OPG was used for evaluation of surgical site, and to decide the length of the implant to be used, based on regional anatomy. IOPA radiographs were taken preoperatively and immediately postoperatively, and subsequently at every follow-up appointment, to assess response to immediate loading. Besides, routine blood investigations and urine examination were done, as in all cases in which any surgical procedure is to be performed. Oral prophylaxis was performed before surgery. Any restorative work was addressed to next. An irreversible hydrocolloid impression was made, and a diagnostic cast was poured in dental stone. Using caliper/dividers, the available mesiodistal width available for the implant was measured. The diameter of the implant was decided based on Misch’s recommendation[5] that an implant placed adjacent to a natural tooth should remain 1.5–2 mm away from the crown in the aesthetic regions. Guidance was also taken from the manufacturer’s recommendations. The length of the implant to be used was decided based on regional anatomical considerations as evident in the OPG. The approximate location of the implant pilot osteotomy was marked on the cast. A hole was drilled at that spot, analogous to the pilot drill, in an angulation, which would facilitate the abutment to take the crown in the most favorable position. A paralleling pin was used to check and correct the angulation. Once the correct angulation was attained, the pin was sealed in the hole with wax. Separating media was applied to the cast. Self curing acrylic was molded over the coronal portion of the pin and labial surfaces of adjacent teeth (as they would provide a stable landmark) and allowed to cure. It was made sure that diameter of the pin was equivalent to the diameter of the pilot drill of the implant surgical kit. The stent was removed from the cast and the pin was removed. It was trimmed of all excesses and smoothened. A preoperative trial was carried out for easy insertion and removal, and pilot drill was passed smoothly, yet snugly through its path. After all necessary adjustments, the stent was sterilized using 2% glutaraldehyde (Cidex) solution. All implant surgeries were performed under local anesthesia. All patients were instructed to a chlorhexidine 2% mouth rinse immediately before surgery. The patient’s face was disinfected with 7.5% povidone–iodine. The oral cavity was prepared with 5% povidone–iodine. Local anesthesia was administered to block regional nerve supply and aid hemostasis. A crestal incision was then placed with two releasing incisions, and a flap was elevated with a No. 9 Molts periosteal elevator, taking care to prevent flap tearing. After adequate exposure of crestal bone, the surgical stent was placed [Figure 2].Figure 2: Incision and flap elevationThe process of implant osteotomy is begun with the punch cut of the pilot drill being made through the hole in the stent, to accurately reproduce the angulation. The stent is removed and the osteotomy is carried to the desired depth. The angulation is checked once again with the paralleling pin, both clinically and radiographically, and any discrepancy found can be corrected subsequently. The osteotomy is then diametrically enlarged to desired width. Continuous internal and external irrigation was done. After osteotomy, the implant was screwed in and tightened using the hardware provided in the surgical kit. It is made sure that a minimum torque of 35 Nm is obtained while screwing in the implant (which is ascertained by the slip of the Ratchet), as this is a prerequisite for immediate loading [Figure 3]. The abutment was attached to the implant with screw provided. The flap was reapproximated and sutured [Figure 4]. The screw hole in the abutment was then blocked with wax. Meanwhile, an irreversible hydrocolloid impression was made and cast poured in die stone. The cast was sent to the prosthodontist who fabricated an immediate acrylic temporary crown, which was cemented onto the abutment on the next day of implant placement. It was made sure that the crown was relieved of occlusal contacts. All patients were prescribed medication and were instructed not to bite hard on the prosthesis. Suture was removed on the seventh postoperative day. The procedures for fabricating the permanent prosthesis were performed in the sixth month following placement [Figure 5]. The patients were given a choice of a full ceramic or metal fused to ceramic crown.Figure 3: Implant placementFigure 4: Wound closureFigure 5: 6th month—permanent crown placementThe response of the patient to the implant and its loading, before osseointegration, was then monitored over a follow-up period of 12 months. The parameters included in the study were recorded four times, that is, in 1st, 3rd, 6th, and 12th month. Our postoperative evaluation of the immediately loaded implants included three parameters to assess the objectives of the study. Implant mobility Soft tissue changes: Peri-implant probing depth Bleeding index Height of marginal bone loss Implant mobility was assessed in similar way as tooth mobility. With two rigid instruments, a force of approx 500g was applied in the labiolingual direction. The amplitude of implant mobility was scored 0–4, according to as given in Table 1.Table 1: Clinical implant mobility scale[6]Peri-implant probing depths It was measured in the same way as for a natural tooth, using a William’s periodontal probe. Probing depths are recorded for each of the four surfaces, and averaged to yield a mean peri-implant probing depth for each implant. Bleeding index The bleeding index used for evaluating our implants was the Silness and Loe Gingival index.[6] This index scores gingival inflammation from 0 to 3 on the facial, palatal, mesial, and distal surfaces of the implant. The scores are based on the presence or absence of bleeding on probing and are scored as follow: Score 0 – normal gingiva; Score 1 – mild inflammation, slight change in colour, slight oedema, no bleeding on probing; Score 2 – moderate inflammation, redness, oedema, and glazing, bleeding on probing; Score 3 – severe inflammation, marked redness and oedema, ulceration tendency to spontaneous bleeding Mean marginal bone levels Mean marginal bone levels were assessed radiographically using the standard IOPA radiographs. The distance between the observed crestal bone level and implant–abutment interface was measured at the mesial and distal implant surfaces and averaged to yield the mean marginal bone loss level for that implant. The actual implant length is known based on manufacturing standards. To adjust the measurements for magnification error, the following equation was used to determine the corrected crestal bone levels:[7] The measurements were classified into groups of 0.5 mm. RESULTS A total of 24 patients, reporting to Government Dental College, desiring replacement of missing teeth in the aesthetic zone of the anterior maxilla were selected, if they satisfied the specified inclusion and exclusion criteria. Also, 24 single tooth implants were placed totally in 24 patients. In all the patients, the implants were loaded with the prosthesis on the same day of placement. Among the 24 patients, 50% (n = 12) were male and 50% (n = 12) were female. The mean age of the patients was 29.91 years (range, 19–42 years). The period of edentulousness ranged from 2 to 24 months, the mean duration being 11.4 months. In all the cases, implants of dimensions 3.7 × 13 mm were used, except in two cases, where the central incisor to be have used implants of dimensions × 13 mm. the prosthesis was fabricated immediately and placed on the postoperative that is, of implant placement. To assess the of the immediately loaded implant, have our follow-up on three clinical and one radiographic implant peri-implant probing bleeding and mean marginal bone The were recorded over follow-up at 1st, 3rd, 6th, and 12th month of implant placement surgery. Implant mobility was according to the implant mobility as described in and In the (n = of the implants absence of any clinical mobility with 500g force in any direction. One implant the presence of a slight (n = In the third and sixth the implant mobility scores with (n = of implants no clinical (n = implants the presence of a slight and one implant = a mobility. In the 12th month the scores were the only being that the of the implant (n = moderate mobility in the third and sixth to severe more than 0.5 mm in Table 2: Implant mobility periodontal was used to check peri-implant probing depth. were recorded for each implant, each to a surface, and then to yield a mean probing depth for each implant. In the (n = implants a probing depth in the of mm, (n = a probing depth in the of 1.5–2 mm, and (n = a probing depth in the of mm. at every interval of 3 and months, probing depth was measured. at 12th only one implant a probing depth 3 mm as in Table The probing depth recorded for these 24 implants was The were found to be and mm in the 1st, 3rd, 6th, and 12th 3: Peri-implant probing bleeding index was by Silness and Loe the of clinical scores of and 3 were to each of the four surfaces, and the mean was The of the obtained is given in Table In the of the implants a bleeding index of which the presence of a mild inflammation surrounding the implant. In of the cases, a of was to a moderate inflammation surrounding the implant. In the third and sixth the bleeding index scores were The mean of the bleeding scores of all the recorded at each follow-up was the of which were and in the 1st, 3rd, 6th, and 12th 4: Bleeding index marginal bone levels were assessed radiographically, using the IOPA The was measured on the After eliminating the by angulation the level of bone loss was classified into groups of 0.5 mm. The were classified and in Table It was found that in the all the implants = a bone that is, 0.5 mm. In the third of the implants bone loss 0.5 mm, and bone loss of mm. In the sixth of implants a mild loss of bone of mm. By the 12th bone loss levels 1 mm, and implants bone loss levels between 1 and 5: bone loss of our study a of with of the 24 immediately loaded implants the of these the and have been Dental implants today have become a highly predictable of replacement of missing The is to function, and and a being reduction of treatment a 3–6 month healing period was by to bone healing and osseointegration before loading. This period was a of both to the patient and and many a the for implant The healing time that is necessary before the implants can be loaded has been proposed as a of clinical than early conditions, such as patient selection with bone and implant surgical protocols, and loading of root form implants has been described in the for eliminating the to healing it was that from early implant loading can in of the implant. In have found that the of bone immediately loaded implants to be than loaded after a evaluation in has osseointegration implants were immediately evaluation from implants that immediate loading has of The need to develop routine implant protocols has been for decreasing or even eliminating the healing periods before loading inserted With better understanding of in implant and surgical protocols, creation of fixed implant supported prostheses via protocols for either immediate and early implant loading (within one to a few weeks of healing) has gradually become available during later years as additional concepts, aiming at reducing the treatment time and treatment costs. This is totally a new way of new to routine “protocols.” In the of once immediately loaded implants have clinically they to take on the of healed and loaded as by the new may even several advantages, including increased masticatory function, minimized uncontrolled transmucosal loading through cross-arch stabilization, improvement of psychological well-being, and reduction in treatment time. have conducted a clinical study with the of evaluating the treatment of 24 immediately loaded implants in the anterior maxilla, that is, the aesthetic For this study 24 patients were selected, based on inclusion and exclusion criteria. were not included in the study, as implants in the region high and loading in The in for anterior and teeth would the and to of the have excluded Patients were excluded if they provided a history of or the presence of any medically compromising conditions, which prohibit implant surgery, such as stroke, recent infarction, severe bleeding disorders, diabetes, osteoporosis, and patients in a minimum torque of Nm was not achieved were also excluded from the study, as that is a prerequisite for immediate These criteria of patient selection were in to given by and and implant have that implant system can be used in immediately loading have selected the from Equinox Medical Technologies B.V., its of surgical The also an in the selection of the implant was to any on After being loaded immediately with the temporary prosthesis, the implant was for months, after which it was with a permanent fused to metal which would be in with its opposite tooth. The between the temporary and permanent prosthesis carried It in the reduction of over the placed and loaded implant during its osseointegration as it was made sure that the would be out of occlusal The temporary prosthesis would also allow any to be made which would be of a permanent ceramic prosthesis. It would allow of the peri-implant soft tissue A temporary would allow easy for any clinical if the need The of the would facilitate and in This in the study is in with the protocols by and and The of our clinical study have that implants in the anterior maxilla may be immediately loaded following The achieved was after 12 months The clinical and parameters of evaluation of implant included in our study were implant peri-implant probing bleeding and mean marginal bone All the four parameters to be in healthy in of 24 implants which is in with the of which have immediately loaded are the to the bleeding which after the sixth or in after of the permanent this to the favorable of the permanent prosthesis, to the temporary prosthesis. An of the obtained in the of this study, and with obtained while to the that immediate loading of dental implants in the aesthetic zone of the maxilla is a highly predictable modality for replacing single missing It be that patient selection a in the of immediately loaded dental a size and follow-up period are necessary before this implant placement can be to the loading and of are no of

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