Rehabilitation of atrophic posterior partial edentulous maxilla with TTPHIL ALL TILT® technique: 3 year follow-up case report

Maxillary sinus pneumatisation pose a grave clinical challenge for implant fixed rehabilitation in posterior maxilla owing to diminished bone volume. This necessitates sinus lift and grafting which increase the duration and cost and possible surgical complications. Pterygoid implant has a greater short term osseointegration and is a proven treatment method for rehabilitation of highly resorbed posterior maxilla. To overcome the limitations of sinus grafting techniques, the current case report describes the use of flapless, tilted and pterygoid implant for restoration of partially edentulous atrophic maxilla eliminating grafting.


Nag et al. INTRODUCTION
A critical determining factor for favourable implant placement is optimal bone in all three dimensions. However, edentulous posterior maxillary rehabilitation using dental implants is frequently accompanied by anatomic constraints, mainly residual ridge resorption and maxillary sinus pneumatisation [1]. This clinical scenario results in the diminished implant survival rates for maxillary posterior fixed rehabilitation [2]. In resorbed posterior maxilla, implant placement with sinus grafting is a common intervention for bone augmentation. However high treatment cost and time, donor site selection and morbidity along with lesser patient acceptance are possible limitations of sinus lifts. Insubstantial bone density in posterior maxilla also affects the outcome of implant success [3].To overcome these negative aspects, treatment options, namely short implants [4]; or fixtures placed in zygoma [5] are documented in the literature. These approaches enhance surgical and prosthetic risks, decreasing the patient acceptance.
Employment of inclined implants harness morphologic features for placement, such as the septa, posterior or anterior wall of sinus, nose corticals, palatal bone, providing an alternative to bone augmentation [6,7]. These implants have significantly aided in the restoration of posterior maxilla by gaining bicortical anchorage and primary stability, thus, improving posterior support for better load distribution. However, it is associated with either biomechanical effects of cantilever or functional effects of reduction in the occlusal units [8]. Accurate bone dimensions can be established with 3D diagnostics, however, the esthetic and functional evaluations can be performed priorly with a single pre-examination operative [9].In patients with minimal bone requiring full mouth implant rehabilitation, chewing ability can be enhanced with implant restoration anchored in maxillary anterior region resulting in cantilevers. Nevertheless, this treatment modality can be unpredictable in partially edentulous arches [10]. To achieve acceptable chewing capacity, optimum support is pertinent for load distribution in the areas of premolar and molar where maximum masticatory function takes place [11]. Further, chewing capacity is dependent on implant distribution in the arch [12]. Therefore, pterygoid implants represent a graftless treatment modality for posterior maxillary rehabilitation that anchors in pterygoid cortical bone, enhancing primary stability and extended success [13]. From a prosthetic perspective, it eliminates distal cantilever and allows to perform an immediate prosthetic load [14].
Guided implant surgery was suggested since last decade to minimize the invasiveness of the surgical procedure through flapless technique [15]. Digital technology employs the localizing capabilities of three-dimensional imaging and executes implant surgery with an appropriate guidance system. The efficacy of digital implant planning and stents to achieve high precision of implant placement into any bone type have been illustrated by various authors [16].
The objective of present case report is to delineate the rehabilitation of atrophic posterior partially edentulous maxilla without sinus grafting employing tilted implant and pterygoid implant.

CASE REPORT
A 61-year-old male visited Institute for Dental Implantology, Hyderabad in March 2018 with the chief complaint of replacement of missing upper back teeth with immediate functional teeth ( Figure 1). Past dental history revealed missing teeth #25,26,27,46. He had visited another clinic and was told that sinus lift along with delayed implant surgery was required due to sinus pneumatisation. However, the patient was not willing for multiple surgeries and had come for a second opinion. The patient also had a crown fracture wrt #47. Following diagnostic orthopantomogram ( Figure 2) and

Nag et al.
Rehabi l i tati on of atrophi c posteri or parti al edentul ous maxi l l a wi th TTPHI L ALL TI LT® techni que: 3 year fol l ow-up case report

Nag et al.
Rehabilitation of atrophic posterior partial edentulous maxilla with TTPHIL ALL TILT® technique: 3 year follow-up case report cone-beam computed tomography (Figure 3), patient was told the option of TTPHIL ALL TILT® technique and the purpose of immediate implants without grafting and immediate function. This technique employs two-piece, long tilted implants engaging the corticals of the nasal bone, maxillary sinus and pterygoids with subcrestal placements in a flapless manner. After taking signed consent for the treatment plan, CBCT DICOM data was used for virtual implant planning and fabrication of stereolithographic model and surgical stents for flapless guided surgery ( Figure 3).

Surgical protocol
Lignocaine with Epinephrine (1:100,000) was administered for the implant surgery. Pre and post surgical medication included Augmentin 625 mg (antibiotic) 1 hour prior to surgery and once daily for next 5 days; prednisone 15 mg to 5 mg (corticosteroid) daily from the day of surgery upto 4 days in a tapering manner; clonidine 300mg (analgesic) once daily for 4 days; Ibuprofen 600 mg (anti-inflammatory) on the fourth day postoperatively; omeprazole 20 mg (antiacid) once daily for 5 days postoperatively were administered. A stereolithographic surgical stent with metal guides was used for flapless placement (Figure 4a). Underdrilling of the implant site using single drill was employed in order to obtain minimum 50 N/cm of primary anchorage enabling immediate function. 20 degrees mesial tilt in relation to the anterior wall of maxillary sinus was used for anterior implant to achieve bicortical anchorage by fixating in nasal cortical (Figure 4b-d). Distally

Prosthetic protocol
An elastomeric impression was performed immediately following the implant surgery (Figure 6b, c). After detaching impression copings, healing abutments were attached. Screw retained metal-ceramic bridge #25,26,27,28 was fabricated and bisque tryin was done on the next day for eliminating excursive contacts (Figure 7a, b). Following glazing, the prosthesis was torqued to 35 N/cm. Review was done the next day, followed up with one week, one, three and six months reviews which were uneventful.

DISCUSSION
Posterior maxilla has limited vertical height availability and has poor marrow quality, vascularity and bone density [17]. Treatment modalities including bone augmentations, sinus grafts and short implants are used for rehabilitation of areas affected by poor quantity and quality bone. Despite their widespread usage among clinicians, the results of these therapeutic options are undermined [18]. Therefore, the treatment modalities are shifting towards minimally invasive immediate function protocols. One such treatment modality is TTPHIL ALL TILT® technique that employs anatomic features of nasal cortical and pterygoid bone aiding in immediate function [19,20]. It also provides second molars without cantilever, unlike    other techniques which eliminate second molars to minimise cantilevers. They are capable of providing support for immediate fixed prostheses owing to osseofixation and high primary stability and subsequent osseointegration [17]. This case report elucidates graftless implant treatment modality along with immediate functional load in resorbed sinus region. The tilting of implants allows placement of longer implants in the available residual bone, enhancing bone-implant contact area and primary anchorage [21]. Utilising anatomic features of the maxillary bone, inclined implants have the advantage of expanding the prosthetic base of the arch [22]. Pterygoid implant is placed posteriorly allowing a greater distance between implants. This favourable interimplant distance facilitates the addition of second molars to the prosthesis along with elimination of cantilever, resulting in better load distribution [21]. The two implants are placed in such a way that a maximum of two pontics were placed between abutments which is significant for biomechanical success [23].Further, longer implants enable their usage in areas of high masticatory loads [24]. This case report is unique due to the combination of tilted anterior implant and pterygoid implant for rehabilitation of four missing posterior teeth.
TTPHIL ALL TILT® technique is used for surgical and prosthetic protocol making it minimally invasive. It utilises the guided implant systems for virtual implant planning and fabrication of stereolithographic models and stents [25]. It enables flapless placement and allows implant placement in deficient bone. The benefits of this implant placement method as a therapeutic option encompasses patientcentric and clinician centric benefits. It shortens surgical time and overall treatment duration by avoiding of grafts thereby reducing treatment cost. Further, it improves clinician's surgical ease as well as patient's acceptance of treatment, especially in severely resorbed posterior maxillary rehabilitations wherein bone harvest is done from morbid sites.
This case report elucidates a severely atrophic posterior maxillae, wherein the use of CBCT images and guided implant planning software allows implant placement and early prosthetic load without grafting. Additional studies with long term follow up are required to substantiate the results of technique. Nevertheless, a guided implant planning system can be the potential aid in rehabilitation of these clinical situations.

CONCLUSION
Use of tilted implants with palatonasal inclination and pterygoid implant with guided implant surgery have rendered satisfactory implant and prosthetic success at 3 year follow-up minimising treatment duration, waiting time and increasing patient acceptance. Nevertheless its use in more number of clinical cases will bring further validation. Rehabilitation of atrophic posterior partial edentulous maxilla with TTPHIL ALL TILT® technique: 3 year follow-up case report

Nag et al.
Rehabi l i tati on of atrophi c posteri or parti al edentul ous maxi l l a wi th TTPHI L ALL TI LT® techni que: 3 year fol l ow-up case report