Abstract
Aim
The aim of the present study was to rehabilitate extensive acquired maxillary defects using zygomatic implant and endosseous dental implant-retained obturator/prosthesis. The objective was to provide a stable, well-retained obturator and to determine the use of zygomatic implants as a reconstructive option to overcome the loss of retentive anatomy following maxillectomy. A total of eight OPD patients - six male and two female of all age groups were selected.
Methodology
Scales assessed were: a) Oral Health impact Profile -14 (OHIP-14) and b) Obturator functioning scale (OFS). Parameters recorded preoperatively and 3 months postoperatively. Clip on denture was delivered to the patient within 7 days with immediate loading concept.
Results
The age groups of the patients ranged between 32 and 54 years with mean age of 44.875. The OHIP-14 scores showed significant differences in all domains with conventional obturator/ with implant-retained obturator: mean functional limitation - 4.13 /0.75; mean physical pain - 5.88 / 0.63. The obturator function scores significantly improved from 4.5 to 30.63.
Conclusion
Although currently limited, the evidence suggests overall good survival rates for the use of zygomatic implants; however, there are varied institutional results reported, most likely due to differing levels of experience with these techniques which have a distinct learning curve.
Keywords: Oral Health impact Profile -14 (OHIP-14), Obturator functioning scale (OFS), Quality of Life (QoL), Zygomatic Implants(ZI)
Introduction
Maxillary defect results in major concerns with mastication, phonetics, deglutition and facial esthetics [1] thereby causing drastic effect on the patients’ oral health-related quality of life (OHR-QoL) [2–5] affecting individual psychological well-being. Rehabilitation of such patients becomes a huge challenge [6] and is of utmost importance to enhance their quality of life. Treatment options for reconstruction include non-vascularized grafts, local flaps, microvascular free tissue graft and maxillary obturator prosthesis [7, 8]. Some patients however prefer not to undergo reconstructive surgeries due to associated secondary morbidity [9], thereby making obturator prosthesis the first line of treatment in such cases. Nevertheless, it is difficult to attain support and retention of obturator due to extensive tooth and tissue loss resulting in unfavorable undercuts and nonkeratinized nasal mucosa. The more extensive the surgical resection, more is the loss of mucogingival support, thereby causing more unfavorable lateral forces on the remaining abutment teeth. The use of implants for enhancing retention of obturator prosthesis has definitely proven to be more effective especially in edentulous unilateral/bilateral maxillectomy defects [10]. However, conventional dental implant (CI) may not be an ideal choice, as there is scarcity of available bone for anchorage. Other methods utilized for enhancing the support and retention of maxillary obturator prosthesis are (1) anatomic favorable undercuts and lateral scar band [10–12]; (2) remaining anatomic structures like the posterior third of the soft palate [12]; (3) titanium hollow reconstruction plate attached to the zygomatic bone [13]; (4) implants placed in the remnant of the maxilla, grafted bone, or distracted bone [11]; (5) zygomatic implants [14–16](ZI) and (6) pterygoid implant [17] (PI).
This study was prospectively designed to reconstruct huge maxillectomy defects with implant-retained obturator (IRO) using zygomatic implants (ZI) and conventional dental implant (CI) and evaluate its role in enhancing the stability and retention of the prosthesis. The study parameters were: a) Oral Health impact Profile-14 (OHIP-14) given by Oliveira BH, Nadanovsky P (2005) [5] and b) Obturator functioning scale (OFS) designed at Memorial Sloan Kettering Cancer Center (New York, NY, USA) developed by Kornblith et al. to assess chewing ability, phonetics and esthetic satisfaction [2]. The study also demonstrates the advantages of using pterygoid implants (PI) with ZI.
Material and Methods
This prospective multidisciplinary study was carried out at a tertiary care dental center from March 2017 to March 2022. Ethical clearance for the conduct of study was obtained from the Local Institutional Ethical Committee. A written informed consent from the patients was obtained. Initially, 10 patients were taken up for the study; however, two maxillectomy patients with history oral squamous cell carcinoma suffered recurrence during follow-up and hence were excluded from the study. A total of eight maxillectomy patients were selected for the placement of implant-retained obturator (IRO) prosthesis. A regular follow-up for a period of 1 year was done for all these patients to rule out any residual disease. All patients were wearing conventional obturator prosthesis preoperatively. Patients with restricted mouth opening; inability of the patient to tolerate anesthesia; presence of maxillary and/or zygomatic pathologic features were excluded. Also, immunocompromised patients—uncontrolled diabetes; long-term drug therapy which interferes with soft tissue and bone healing such as bisphosphonates; radiotherapy/chemotherapy patients, smokers, long-term steroid therapy and poorly motivated patients with unacceptable oral hygiene were excluded from the study to avoid bias.
All patients underwent routine investigations to assess general health and specific preoperative investigations for dental implants in the form of orthopantomogram (OPG) and cone-beam computed tomography (CBCT) to determine the available residual bone, its quality, quantity and to plan the path of implant placement as shown in Fig. 1.
Fig. 1.
CBCT planning of implants
Treatment planning was done based on the available residual bone in the maxillectomy defect i.e., the choice and number of implants. In cases where bone was available in the anterior maxilla, one or two anterior CI along with one or two ZI was planned. If bone was unable in the anterior maxilla, one or two ZI along with PI was planned giving a tripod effect. Cross-arch stabilization was achieved in unilateral maxillectomy cases with palatal plate of obturator extending to the unaffected side. Cases with B/L maxillectomy defect were similarly planned considering the available residual bone in anterior maxilla, zygomatic bone and pterygoid bone. Since the study had a limited sample size so grouping could not be done. After recording the case history systematically, and initial assessment of their OHIP-14 and OFS; selected patients wearing conventional obturator were taken up for implant placement under local or general anesthesia. Surface marking was done prior to implant placement to mark the bony orbit and targeted zygomatic bone as depicted in Fig. 2. Implants were placed as per the treatment plan and multiunit abutment placed subsequently as shown in Figs. 3 and 4. Postoperative radiograph OPG was taken for reference (Figs. 3 and 4).
Fig. 2.
Anatomic landmarks for zygomatic implant placement i.e., the bony orbit and zygoma marked
Fig. 3.
Case of B/L maxillectomy defect
Fig. 4.
-Case of unilateral maxillectomy defect
Of total eight patients taken up for the study these were six males and two females with age ranging between 32 and 54 years and mean age 44.9 years, hence providing a wide age distribution. The most common cause of maxillectomy was osteomyelitis (five cases) followed by squamous cell carcinoma (two cases) and trauma related loss of bone (one case). The surgical defect was classified as per Brown’s classification (Fig. 5), five patients were class 2a, one patient each of class 2b, class 2c and class 3a (Table 1). All cases were taken up for secondary implant placement with immediate loading protocol, i.e., the implants were placed between 6-month and 1-year post-maxillectomy and implant supported prosthesis delivered within 7 days after implant placement. Two maxillectomy patients with history of oral squamous cell carcinoma were followed for period of 2-year post-maxillectomy before placement of implants.
Fig. 5.
Brown’s classification of Maxillectomy defects
Table 1.
Master sheet
| Patient | Age | Sex | Gender | Pathology | Type of pathology | Maxillectomy classification | Maxillectomy type | No of teeth remaining in the upper arch |
|---|---|---|---|---|---|---|---|---|
| 1 | 47 | M | 2 | SCC | Hemimaxillectomy defect | 2a | 0 | 6 |
| 2 | 42 | F | 1 | Osteomyelitis (Mucormycosis) | Complete B/L Maxillectomy defect | 2c | 2 | 0 |
| 3 | 51 | M | 2 | Osteomyelitis | Hemimaxillectomy defect | 2a | 0 | 7 |
| 4 | 45 | F | 1 | Osteomyelitis (Mucormycosis) | Hemimaxillectomy defect | 2b | 1 | 3 |
| 5 | 53 | M | 2 | SCC | Hemimaxillectomy defect | 2a | 0 | 8 |
| 6 | 35 | M | 2 | Osteomyelitis (Mucormycosis) | Hemimaxillectomy defect | 2a | 0 | 6 |
| 7 | 54 | M | 2 | Trauma related bone loss | Hemimaxillectomy defect | 2a | 0 | 8 |
| 8 | 32 | M | 2 | Osteomyelitis (Mucormycosis) | Hemimaxillectomy defect | 3a | 3 | 7 |
| Patient | Number of implants placed | Type of surgery | Quality of bone in Zygomatic region and Pterygoid region | Length of implants ZI/PI | Width of implants ZI /PI | Length of dental implant | Width of dental implant | Success/failure | OHIP (pre-treatment) |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 3 | WLE | D1/D2 | ZI 37.5;35 | 4.2 | 13 | 4.2 | Success 02; failure 01(ZI) | 41 |
| 2 | 6 | Debridement | D2/D3 | ZI 35,37.5,35,35;PI 22,18 | 4.2 | not placed | not placed | Success 05; failure 01(PI) | 43 |
| 3 | 3 | Debridement | D2/D3 | ZI 35;PI22 | 4.2 | 11.5 | 3.75 | Success 03/failure nil | 33 |
| 4 | 4 | Debridement | D2/D2 | ZI 35,37.5;PI 18 | 4.2 | 13 | 4.2 | Success 04/failure nil | 39 |
| 5 | 3 | WLE | D1/D2 | ZI 40;PI 18 | 4.2 | 16 | 4.2 | Success 03/failure nil | 46 |
| 6 | 2 | Debridement | D2/D3 | ZI 40 | 4.2 | 11.5 | 4.2 | Success 01/failure 01(ZI) | 28 |
| 7 | 3 | ORIF | D1/D2 | ZI 37.5;PI 18 | 4.2 | 10 | 3.75 | Success 03/failure nil | 39 |
| 8 | 3 | Debridement | D1/D2 | ZI 40;PI 22 | 4.2 | 16 | 3.75 | Success 03/failure nil | 43 |
| Patient | OHIP (post-treatment) | OFS (pre-treatment) | OFS (post-treatment) | Pre-treatment-functional limitation | Post-treatment-functional limitation | Pre-treatment-physical pain | Post-treatment-physical pain | Pre-treatment-psychological discomfort | Post-treatment-psychological discomfort |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 14 | 34 | 15 | 6 | 3 | 6 | 1 | 7 | 4 |
| 2 | 8 | 43 | 10 | 4 | 1 | 6 | 2 | 5 | 3 |
| 3 | 2 | 21 | 0 | 3 | 0 | 6 | 0 | 6 | 1 |
| 4 | 3 | 42 | 2 | 4 | 0 | 6 | 0 | 5 | 2 |
| 5 | 6 | 28 | 2 | 7 | 2 | 6 | 1 | 7 | 1 |
| 6 | 2 | 22 | 0 | 1 | 0 | 5 | 0 | 6 | 1 |
| 7 | 2 | 14 | 0 | 4 | 0 | 6 | 0 | 6 | 1 |
| 8 | 5 | 41 | 7 | 4 | 0 | 6 | 1 | 7 | 2 |
| Patient | Pre-treatment-physical disability | Post-treatment-physical disability | Pre-treatment-psychological disability | Post-treatment-psychological disability | Pre-treatment-social disability | Post-treatment-social disability | Pre-treatment-handicapness | Post-treatment-handicapness |
|---|---|---|---|---|---|---|---|---|
| 1 | 8 | 1 | 6 | 2 | 8 | 2 | 0 | 1 |
| 2 | 8 | 0 | 7 | 0 | 8 | 2 | 5 | 0 |
| 3 | 6 | 0 | 6 | 0 | 6 | 1 | 0 | 0 |
| 4 | 8 | 0 | 7 | 0 | 8 | 1 | 1 | 0 |
| 5 | 8 | 0 | 7 | 0 | 8 | 2 | 3 | 0 |
| 6 | 6 | 0 | 4 | 0 | 5 | 1 | 1 | 0 |
| 7 | 8 | 0 | 5 | 0 | 8 | 1 | 2 | 0 |
| 8 | 8 | 0 | 7 | 0 | 8 | 2 | 3 | 0 |
The CI chosen ranged from 3.5 to 5.0 mm in width and 8.5–13 mm in length; ZI being 4–4.4 mm in width and 30–47.5 mm in length and PI ranged from 4 to 4.4 mm in width and 18-22 mm in length, respectively. All patients received IRO with clip on attachments. Clip on prosthesis over a fixed metal framework screwed over multiunit abutment was delivered to the patient within 7 days with immediate loading concept.
A total of 12 ZI implants, 07 CI implants and 08 PI implants were placed. Data analysis was done at 3-month post-insertion of IRO and all patients were followed for a minimum of 6-months to 2-year duration.
Three implants—two zygoma and one pterygoid implants failed in function over a period of 3 to 6 months. One zygoma implant failed in a case where tripoding could not be established due to bone deficiency in both anterior maxilla and pterygoid region. There was abutment screw fracture in one pterygoid implant; therefore, it could not be utilized for the metal framework and was hence considered failed implant.
RESULTS AND STATISTICAL ANALYSIS: At the follow-up appointments, oral health-related quality of life was assessed using OHIP-14 and OFS Scales.
Oral Health impact Profile-14 (OHIP-14): A low score (= 0) indicates no impairment, to the highest score (= 56) indicating maximal impairment. OHIP-14 consists of seven domains: functional limitation, physical pain, psychological discomfort, physical disability, psychological disability, social disability and handicap.
Obturator functioning scale (OFS) uses a 5-point Likert scale (“not at all”, “a little difficult”, “somewhat difficult”, “very difficult” “and extremely difficult”). In the absence of visual clues, a speech tool was added i.e., “difficulty in talking on the phone”, to assess communication difficulties. Patient's responses were coded from 1 (“not at all”) to 5 (“extremely difficult”).
Parameters were recorded preoperatively i.e., with conventional obturator prosthesis and 3-month postoperatively after placement of IRO. Initially, Student's ‘t’ test was attempted to analyze the data statistically. However, as the analytic values were not normally distributed and sample size was too small, alternative statistical analytic tests: a) Mann–Whitney test and b) Wilcoxon test were carried out. The results were tabulated and analyzed. OHIP-14 scores and the obturator function scores before and after completion of treatment are shown in Tables 2 and 3, respectively. OHIP-14 scores and the OFS showed significant differences between conventional obturator versus implant-retained obturator; mean OFS1 (with conventional obturator) being 30.63 and OFS 2 (with IRO) 4.5. The mean OHIP-14 score with conventional obturator was 39 and with IRO was 5.25 (See Table 4). There is a definite improvement post-treatment in oral health-related quality of life which could be attributed to multiple factors such as extensive psychological counseling, improvement in chewing efficiency, speech and taste and prosthesis stability after treatment which enhances the mental well-being of the patient.
Table 2.
Analysis sheet
| Patients | Age | Gender | Type of pathology | Maxillectomy type | No of remaining teeth | Number of implants placed | Outcome | Pre-treatment-functional limitation |
|---|---|---|---|---|---|---|---|---|
| 1 | 47 | 2 | 4 | 0 | 6 | 3 | 0 | 6 |
| 2 | 42 | 1 | 3 | 2 | 0 | 6 | 1 | 4 |
| 3 | 51 | 2 | 2 | 0 | 7 | 3 | 1 | 3 |
| 4 | 45 | 1 | 3 | 1 | 3 | 4 | 0 | 4 |
| 5 | 53 | 2 | 4 | 0 | 8 | 3 | 1 | 7 |
| 6 | 35 | 2 | 3 | 0 | 6 | 2 | 1 | 1 |
| 7 | 54 | 2 | 1 | 0 | 10 | 3 | 1 | 4 |
| 8 | 32 | 2 | 3 | 3 | 7 | 3 | 1 | 4 |
| Patient | Post-treatment-functional limitation | Pre-treatment-physical pain | Post-treatment-Physical Pain | Pre-treatment-psychological discomfort | Post-treatment-psychological discomfort | Pre-treatment-physical disability | Post-treatment-physical disability | Pre-treatment-psychological disability | Post-treatment-psychological disability |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 3 | 6 | 1 | 7 | 4 | 8 | 1 | 6 | 2 |
| 2 | 1 | 6 | 2 | 5 | 3 | 8 | 0 | 7 | 0 |
| 3 | 0 | 6 | 0 | 6 | 1 | 6 | 0 | 6 | 0 |
| 4 | 0 | 6 | 0 | 5 | 2 | 8 | 0 | 7 | 0 |
| 5 | 2 | 6 | 1 | 7 | 1 | 8 | 0 | 7 | 0 |
| 6 | 0 | 5 | 0 | 6 | 1 | 6 | 0 | 4 | 0 |
| 7 | 0 | 6 | 0 | 6 | 1 | 8 | 0 | 5 | 0 |
| 8 | 0 | 6 | 1 | 7 | 2 | 8 | 0 | 7 | 0 |
| Patient | Pre-treatment-social disability | Post-treatment-social disability | Pre-treatment-handicapness | Post-treatment-handicapness | OHIP (pre-treatment) | OHIP (post-treatment) | OFS (pre-treatment) | OFS (post-treatment) |
|---|---|---|---|---|---|---|---|---|
| 1 | 8 | 2 | 0 | 1 | 41 | 14 | 34 | 15 |
| 2 | 8 | 2 | 5 | 0 | 43 | 8 | 43 | 10 |
| 3 | 6 | 1 | 0 | 0 | 33 | 2 | 21 | 0 |
| 4 | 8 | 1 | 1 | 0 | 39 | 3 | 42 | 2 |
| 5 | 8 | 2 | 3 | 0 | 46 | 6 | 28 | 2 |
| 6 | 5 | 1 | 1 | 0 | 28 | 2 | 22 | 0 |
| 7 | 8 | 1 | 2 | 0 | 39 | 2 | 14 | 0 |
| 8 | 8 | 2 | 3 | 0 | 43 | 5 | 41 | 7 |
Table 3.
Normality test
| Pre-treatment-functional limitation | Post-treatment-functional limitation | Pre-treatment-physical pain | Post-treatment-physical pain | Pre-treatment-psychological discomfort | Post-treatment-psychological discomfort | Pre-treatment-physical disability | Post-treatment-physical disability | Pre-treatment-psychological disability | |
|---|---|---|---|---|---|---|---|---|---|
| N | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 |
| Shapiro–Wilk W | 0.9167 | 0.7242 | 0.4184 | 0.7976 | 0.8352 | 0.8089 | 0.5659 | 0.4184 | 0.8089 |
| p(normal) | 0.4037 | 0.004214 | 1.05E-06 | 0.02697 | 0.06724 | 0.03563 | 6.32E-05 | 1.05E-06 | 0.03563 |
| Post-treatment-psychological disability | Pre-treatment-social disability | Post-treatment-social disability | Pre-treatment-handicapness | Post-treatment-handicapness | OHIP (pre-treatment) | OHIP (post-treatment) | OFS (pre-treatment) | OFS (post-treatment) | |
|---|---|---|---|---|---|---|---|---|---|
| N | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 | 8 |
| Shapiro–Wilk W | 0.4184 | 0.6068 | 0.6647 | 0.9194 | 0.4184 | 0.9134 | 0.8184 | 0.9108 | 0.8241 |
| p(normal) | 1.05E-06 | 0.000191 | 0.000892 | 0.425 | 1.05E-06 | 0.3786 | 0.04493 | 0.3599 | 0.0515 |
Table 4.
Results
| Descriptive Analysis | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| N | Mean | Std. deviation | Minimum | Maximum | Mean | Std. deviation | Minimum | Maximum | ||
| Pre-treatment-functional limitation | 8 | 4.13 | 1.808 | 1 | 7 | Post-treatment-functional limitation | 0.75 | 1.165 | 0 | 3 |
| Pre-treatment-physical pain | 8 | 5.88 | 0.354 | 5 | 6 | Post-treatment-physical pain | 0.63 | 0.744 | 0 | 2 |
| Pre-treatment-psychological discomfort | 8 | 6.13 | 0.835 | 5 | 7 | Post-treatment-psychological discomfort | 1.88 | 1.126 | 1 | 4 |
| Pre-treatment-physical disability | 8 | 7.5 | 0.926 | 6 | 8 | Post-treatment-physical disability | 0.13 | 0.354 | 0 | 1 |
| Pre-treatment-psychological disability | 8 | 6.12 | 1.126 | 4 | 7 | Post-treatment-psychological disability | 0.25 | 0.707 | 0 | 2 |
| Pre-treatment-social disability | 8 | 7.38 | 1.188 | 5 | 8 | Post-treatment-social disability | 1.5 | 0.535 | 1 | Pre-treatment-social disability |
| Pre-treatment-handicapness | 8 | 1.88 | 1.727 | 0 | 5 | Post-treatment-handicapness | 0.13 | 0.354 | 0 | 1 |
| OHIP (Pre-treatment) | 8 | 39 | 5.88 | 28 | 46 | OHIP (post-treatment) | 5.25 | 4.166 | 2 | 14 |
| OFS (Pre-treatment) | 8 | 30.63 | 11.032 | 14 | 43 | OFS (post-treatment) | 4.5 | 5.606 | 0 | 15 |
| Wilcoxon test result | |||
|---|---|---|---|
| Z | Asymp. Sig. (2-tailed) | Effect size | |
| Pre-treatment-functional limitation | − 2.546 | 0.011 | − 0.90284 |
| Pre-treatment-physical pain | − 2.565 | 0.01 | − 0.90957 |
| Pre-treatment-psychological discomfort | − 2.555 | 0.011 | − 0.90603 |
| Pre-treatment-physical disability | − 2.588 | 0.01 | − 0.91773 |
| Pre-treatment-psychological disability | − 2.555 | 0.011 | − 0.90603 |
| Pre-treatment-social disability | − 2.555 | 0.011 | − 0.90603 |
| Pre-treatment-handicapness | − 2.047 | 0.041 | − 0.72589 |
| OHIP (pre-treatment) | − 2.521 | 0.012 | − 0.89397 |
| OFS (pre-treatment) | − 2.521 | 0.012 | − 0.89397 |
Discussion
Patients with maxillary defects need immediate restoration to function and hence primary implant placement, i.e., implant placement during the maxillectomy surgery with immediate or early loading protocols wherever possible is optimum to regain faster recovery in such patients. Butterworth (2019) reported a huge sample size of 131 ZI with a 10-year follow-up study [18]. He found that out of the 131 implants placed, nine implants failed in four patients. In his study, he loaded 27 out of 49 patients (primary placement group) within 1.7 months and 22 patients in secondary group with delayed loading protocol. He found that secondary group had higher failure rates (11%) compared to primary group with only 4% failures. Here, the secondary group also included radiotherapy patients. Eight patients were irradiated before implant placement and 15 patients in the primary group were irradiated immediately postoperatively [18]. The high survival rates reported in this large series demonstrate that successful integration can occur in irradiated patients. In our study, all cases were taken up for secondary implant placement with immediate loading protocol, i.e., the implants were placed between 6-months and 1-year post-maxillectomy and IRO delivered within 7 days of implant placement. Two maxillectomy patients with history of oral squamous cell carcinoma were followed for period of 2-year post-maxillectomy before placement of implants. Our study revealed overall implant survival rate of 88.89%, 02 of 11 ZI (success rate 81.8%) and 01 of 08 PI (success rate 87.5%) failed. Conventional implants 7 in number were placed with 100% survival. In our study, radiotherapy patients were excluded. Further studies with larger sample size will be required to assess the effect of radiotherapy with such implants. Schmidt, Pogrel, Young & Sharma, 2004 revealed the lowest survival rate of 77% which occurred at stage 2 implant surgery prior to prosthetic rehabilitation [20].
Recent literature search revealed various ZI loading protocols including immediate, early and delayed loading. Pellegrino et al. in 2015 used immediate loading with ZI and provided a definitive prosthesis within 3 months. One implant failed after 8 months of loading [21]. Most studies used delayed loading protocol with ZI and provided temporary obturators during this interim time (Atalay, Doganay, Saraçoğlu, Bultan, & Hafiz, 2017; Huang et al., 2014; Landes et al., 2009) [19, 21]. In the present study, all eight patients were managed with immediate loading concept with overall survival rate of 88.89% and failure of 03 implants with overall failure rate of 11.11%.
Axial loading of the implants by cross-arch stabilization using a minimum of four implants splinted together with a rigid framework giving adequate anterior–posterior spread is most effective way of achieving stability to the prosthesis, it is also recommended by Professor Branemark. However, in unilateral maxillectomy cases with advantage of tooth and tissue support from the unaffected side, unilateral (single or two) ZI placement on the defect side has proven to be beneficial (Qu, Wang, Ong, & Zhang, 2016) [22]. In our study group, two patients required cross-arch splinting, one patient with class 2c and other patient with class 2b maxillectomy defect. Rest six cases had unilateral ZI and did not require cross-arch splinting. However, to enhance stability of the prosthesis, either/both one anterior and one pterygoid implant was placed in these cases.
Although most studies favor removable prostheses, some studies reported fixed prosthesis on zygomatic implants (Boyes-Varley et al., 2007; Butterworth, 2019; Pellegrino et al., 2015;) [18, 19, 21] with very few complications. In the present study, we witnessed one case of screw fracture. In our study, all eight patients were delivered with zygomatic implant-retained obturator prosthesis with fixed rigid framework and clip on bar design. An improved oral health-related quality of life has become the main goal in prosthetic rehabilitation. Most authors found that patients with orofacial carcinoma who received IRO with ZI had postoperatively favorable speech (Huang et al., 2014; Lu, Wang, Yang, & Yan, 2013; Schmidt et al., 2004), acceptable esthetics or facial contour (Huang et al., 2014; Schmidt et al., 2004) and adequate eating and drinking function without regurgitation or nasal leakage (Schmidt et al., 2004). Butterworth (2019) used University of Washington-QoL scale (UW-QOL)—questionnaire that provides questions specific to patients with orofacial carcinoma and were concise yet multifactorial (Lowe & Rogers, 2012). In the present study group, majority patients (87.5%) were non-oncological cases; hence, Oral Health impact Profile -14 (OHIP-14) and Obturator Function Score (OFS) were utilized for assessment of quality of life. The mean OHIP-14 score with conventional obturator was 39 and with IRO was 5.25. (See Table 2). Results showed that IRO significantly improved Oral health-related quality of life in six of the seven domains. The remaining domain (psychological discomfort) showed no significant differences before and after treatment, but we found that the score for psychological discomfort also revealed improvement. Furthermore, the OFS scores were significantly improved after treatment; mean OFS1 (with conventional obturator) was 30.63 and mean OFS 2 (with IRO) was 4.5.
The success criteria of a ZI used in the literature are varied and inconsistent. Certain unique aspects of ZIs, quoted by different authors [23, 24], are: Longer implant needs special instrumentation; non-axial placement and an extra-sinus or extra-maxillary path to reach the zygomatic bone. Different complications, like sinus infection or soft tissue recession, may appear after its placement on the extremely resorbed maxilla with a flat palate. Also, it is prudent to keep in mind that ZI is not designed to be osseointegrated throughout their whole length. When ZI faces non-axial forces, we can observe a slight movement without it being symptomatic or pathologic. Zwahlen et al. in 2006, Davó et al. 2008, and Bedrossian in 2010 [25] proposed the absence of rotational movement of the ZI as an essential criterion of stability and related it to survival/success of the implant. Rotational stability has been examined in different ways such as manual tests, reverse torque or tightening of the abutment screw at different degrees of torque. Rotational movement of a ZI is a failure criterion and justifies the removal of the implant.
Frequently, the absence of pain is also success criteria in the evaluation of ZI [25, 26]. A retrospective study of ZI conducted by Maló et al. [27] advices the absence of complications as survival criteria. These authors evaluated the presence of three types of complications: a) Biological complications: soft tissue inflammation, fistula formation, pain or maxillary sinus infections. b) Esthetic complications: esthetic complaints of the patient. c) Functional complications: phonetic, masticatory, comfort or hygiene complaints. Based on the studies, the ZI body exposure should not be associated with failure. However, soft tissue dehiscence does make hygiene difficult and may lead to other complications such as sinus communications, esthetic complaints, mucositis or extensive cellulitis. The recent zygomatic implants have mechanized surfaces at the coronal part, rough surfaces at the apex and reduced threads in the body and the cervical third of the implant. These features may reduce gingival recession and facilitate hygiene in case of exposure [27]. There are four specific objective criteria to describe the success/outcome of ZI. The ORIS acronym is the suggested name for the new criteria: (1) Offset: evaluation of prosthetic success based on final ZI positioning, (2) Rhinosinus status report: a pre- and post-surgical CBCT comparative approach to evaluate whether sinuses are healthy, (3) Infection permanence related to dehiscence and (4) Stability report: accepting as success criteria until no osseointegration or mobility, signs of rotation or apical pain present [27]. In our study, all patients were followed for a minimum of 6-month to 2-year duration and 2 of 11 ZI (success rate 81.8%) and 01 of 08 PI (success rate 87.5%) failed in function over a period of 3 to 6 months.
Conclusion
Reconstruction is standard treatment modality for maxillary defects, particularly for larger defects. However, rehabilitation with a prosthetic obturator after maxillectomy has the advantage of a shorter, less complex operative procedure and quicker recovery. IRO with use of ZI has significantly changed the stability and retention of obturators. The placement of ZI is a major surgical procedure, and proper training is needed. Based on the current literature review, ZI shows excellent survival rates (> 90%) and a low incidence of complications, so it may be considered as a valid and safe treatment option when dealing with patients with maxillary defects. Pterygoid implants may add up to the stability of IRO. Small sample size was a limitation of this study; hence, a prospective, longitudinal study to identify role of ZI and PI in maxillectomy patients with a larger cohort should be considered in future.
Acknowledgements
We acknowledge Dr Kapil Tomar for his initial work on the project.
Footnotes
Publisher's Note
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