UNIVERSIDADE ESTADUAL PAULISTA
“JÚLIO DE MESQUITA FILHO”
Instituto de Ciência e Tecnologia
Campus de São José dos Campos
ORIGINAL ARTICLE DOI: https://doi.org/10.4322/bds.2025.e4609
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Braz Dent Sci 2025 Jan/Mar;28 (1): e4609
This is an Open Access article distributed under the terms of the Creative Commons Attribution license (https://creativecommons.org/licenses/by/4.0/), which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Wear of two different attachment systems in implant supported
mandibular overdentures: a clinical comparative study
Desgaste de dois sistemas de attachments diferentes em overdentures mandibulares suportadas por implantes: um estudo
clínico comparativo
Ammar Omar BELAL1 , Moataz Mostafa Bahgat ELMAHDY1 , Sayed Mohammed Mohammed ELMASRY1 ,
Mohamed Ezzat ELSAYED1
1 - Suez Canal University, Faculty of Dentistry, Prosthetic Dentistry, Ismailia, Egypt.
How to cite: Belal AO, Elmahdy MMB, Elmasry SMM, Elsayed ME. Wear of two different attachment systems in implant supported
mandibular overdentures: a clinical comparative study. Braz Dent Sci. 2025;28(1):e4609. https://doi.org/10.4322/bds.2025.e4609
ABSTRACT
Introduction: The stud attachment is regarded as one of the most popular systems for the retention of removable
overdentures. A new type of PEEK attachment system, such as Novaloc, may have a good prognosis compared
to other systems. Aim of the study: The purpose of this clinical study is to compare two different attachment
systems, Novaloc and Locator, regarding wear resistance under implant-supported overdentures. Material and
Methods: The research sample consisted of 10 patients with complete lower and upper edentulous. A complete
lower denture was made supported by two implants, with a conventional complete denture for each patient. The
patients were divided equally into Group 1: Novaloc attachment system. Group 2: Locator attachment system.
The wear measurements were done using a digital stereomicroscope and repeated after 4, 8, and 12 months. The
data was collected, calculated, and statistically analyzed using the SPSS program. Results: According to One-way
ANOVAs and independent T-test and throughout the observation period (P-Value > 0.05). The results showed
the presence of wear in both attachment systems, but with statistically signicant differences, as the amount of
wear was greater in the Locator group compared to the Novaloc group. Conclusion: Under the circumstances
of this study, it can be concluded that the Novaloc attachment system is superior to the Locator in terms of its
resistance to wear during the observation period of 1 year when compared to the Locator system.
KEYWORDS
Attachments; Locator; Novaloc; Nylon; Overdenture; PEEK; Wear.
RESUMO
Introdução: A xação por Attachments é considerada como um dos sistemas mais populares para a retenção de
overdentures removíveis. Um novo tipo de sistema de xação PEEK, como o Novaloc, pode ter um bom prognóstico
em comparação com outros sistemas. Objetivo do estudo: O objetivo deste estudo clínico é comparar dois sistemas
de Attachments diferentes, Novaloc e Locator, com relação à resistência ao desgaste sob overdentures suportadas
por implantes. Material e Métodos: A amostra da investigação foi constituída por 10 pacientes desdentados totais
inferiores e superiores. Foi realizada uma prótese total inferior suportada por dois implantes, e uma prótese total
convencional para cada paciente. Os pacientes foram divididos igualmente em Grupo 1: Sistema de xação Novaloc.
Grupo 2: Sistema de xação Locator. As medições de desgaste foram efetuadas utilizando um estereomicroscópio
digital e repetidas após 4, 8 e 12 meses. Os dados foram recolhidos, calculados e analisados estatisticamente
utilizando o programa SPSS. Resultados: De acordo com as ANOVAs One-way e o teste T independente ao longo
do período de observação (p-valor > 0,05). Os resultados mostraram a presença de desgaste em ambos os sistemas
de xação, mas com diferenças estatisticamente signicativas, pois a quantidade de desgaste foi maior no grupo
Locator em relação ao grupo Novaloc. Conclusão: Nas circunstâncias deste estudo, pode-se concluir que o sistema
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Braz Dent Sci 2025 Jan/Mar;28 (1): e4609
Belal AO et al.
Wear of two different attachment systems in implant supported mandibular overdentures: a clinical comparative study
Belal AO et al. Wear of two different attachment systems in implant supported
mandibular overdentures: a clinical comparative study
INTRODUCTION
Retention and stability are important factors
in the successful fabrication of a complete
denture [1,2]. Today implant-supported
mandibular overdentures retained by two
implants with unpainted systems (ring-ball-
cylindrical types) or splinted systems (bar
attachment) associated with a maxillary complete
denture have been proposed as the rst choice of
treatment for edentulous patients [3], and this
treatment seeks to provide better stability and
retention of the mandibular complete denture,
thus improving the masticatory function of
the patient and providing greater satisfaction,
better oral health-related quality of life and
comfort, therefore, knowledge of the different
attachment systems and an understanding of their
mechanical properties, such as retention and load
distribution, could help clinicians select the proper
attachment for each case [4,5]. The cylindrical
attachment systems, which were made from PEEK
material, such as the Novaloc or nylon systems
like the Locator, were created to address specic
indications, such as smaller prosthesis spaces,
because of their improved retention and smaller
size [6,7]. Due to its improved dual retention
over the last two decades, the locator has become
the most cylindrical type with the lowest prole
height. The matrix is composed of a polyethylene
retention device and a 1.2 mm internal retention
pin that can withstand an 8-degree maximum
angulation in all directions [8-10]. But like any
mechanical equipment, the locator will inevitably
develop more mechanical issues with time. The
male nylon inserts of the locator attachment have
been seen to wear out excessively and demand
more maintenance over time, which has resulted
in a loss of retention [11]. On the other hand,
the Novaloc retention device is placed in titanium
or Poly-ether-ether-ketone (PEEK) casings and is
constructed of PEEK to increase wear resistance,
which revealed encouraging ndings in a few in
vitro studies of the long-term retention of peek
retention devices [12-14]. To date of this article,
there are not many clinical studies comparing
these two types, although there was a study
by Abdelaziz et al. 2021 [15] which compares
the PEEK and nylon insert in the locator system
only. Therefore, to reduce this gap in existing
literature, this clinical study was conducted to
assess these two different attachment systems,
Novaloc and Locator, regarding wear resistance
under implant-supported overdentures.
MATERIALS AND METHODS
This clinical research was a case-controlled
trial. It was made at the Department of Prosthetics
Dentistry at the Faculty of Dentistry at Suez Canal
University, after the Scientic Research Ethics
Committee with code number: 2021-40.
The research sample consisted of ten
complete edentulous patients. The sample
size was calculated using Open-Epi version
3.01 (Emory University, USA) at a condence
interval of 95% with one ratio to compare equal
groups.
The patients were selected randomly without
regard to gender or age. All the patients had
good oral and physical health and were accepted
based on the following inclusion criteria: all
patients had maxillary and mandibular alveolar
ridges covered with healthy tissue, Sufficient
mandibular alveolar bone conrmed by CBCT,
six months at the last extraction, and sufcient
inter-jaw space, which was conrmed using the
putty index technique. Exclusion criteria were
parafunctional habits, alcoholism, a history of
radiation therapy in the head and neck region or
temporomandibular joint disorders, and systemic
diseases that can affect the success of implants.
After explaining the work and study steps to
the patients and obtaining their approval through
consent. A conventional acrylic complete upper
and lower removable denture was produced using
the standard procedures that are recognized in
the academic community. Primary upper and
lower impressions were taken as part of the
process, and a nal impression was taken using
cold acrylic cured trays after border molding to
create the wash impression. The jaw relation was
de xação Novaloc é superior ao Locator em termos da sua resistência ao desgaste durante o período de observação
de 1 ano, quando comparado com o sistema Locator.
PALAVRAS-CHAVE
Encaixes de precisão; Nylon; Sobredentadura; Desgaste de restauração dental; Implantes dentários.
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Braz Dent Sci 2025 Jan/Mar;28 (1): e4609
Belal AO et al.
Wear of two different attachment systems in implant supported mandibular overdentures: a clinical comparative study
Belal AO et al. Wear of two different attachment systems in implant supported
mandibular overdentures: a clinical comparative study
then registered using record bases, articial teeth
were arranged, try-ins were made, dentures were
waxed up, asking procedures were made, and
the outcome was made in the patient’s mouth
with any modications that were required for
the dentures.
After that, the patients were divided equally
into: Group 1: Novaloc attachment system. Group
2: Locator attachment system.
A apless implant placement approach and
conventional loading were intended. Therefore,
a surgical guide was made using the CAD-CAM to
guarantee the implant’s accurate placement and
orientation in the canine area (Figure 1).
Each patient received two bone Straumann
implants (Straumann Dental Implant System,
Switzerland), which were 3.3 mm in diameter
and 13 mm in length. (Figure 2). After three
months, and according to the conventional
loading protocol to ensure that the implants can
be loaded. Implants were assessed clinically,
showing no signs of pain or inflammation,
and a radiograph image demonstrated no
bone resorption around the implants. After
that, implants were exposed, and mounting of
the implant system smart peg. The resonance
frequency analysis system (Mega ISQ System,
South Korea) was used to evaluate the secondary
stability and readiness to be loaded based on
scientic recommendations.
After that, both Novaloc (Straumann,
Möhlin, Switzerland) and Locator (Zest Anchors,
Escondido, USA) were placed in the implants and
tightened using the driver for each attachment
and tightened using the torque ratchet wrench
according to the manufacturer’s instructions
(30 Newton). For all patients, the direct
pick-up method was applied to incorporate
Novaloc retention inserts and Locator retention
replacement males (Figure 3).
Wear measurements were done immediately
after the placement of the dentures at the
Faculty of Agriculture at Mansoura University,
utilizing a professional camera (10MP Tucsen
Figure 1. (a) Intraoral view of the upper jaw. (b) Intraoral view of the lower jaw. (c) Conventional Complete denture. (d): surgical guide design
with parallel axes.
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Braz Dent Sci 2025 Jan/Mar;28 (1): e4609
Belal AO et al.
Wear of two different attachment systems in implant supported mandibular overdentures: a clinical comparative study
Belal AO et al. Wear of two different attachment systems in implant supported
mandibular overdentures: a clinical comparative study
Figure 2. (a) Check parallelism. (b) Straumann Dental Implant System.
Figure 3. (a) Novaloc attachments were screwed. (b) Novaloc retention inserts. (c) Locator attachments were screwed. (d) Locator retention
replacement male.
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Braz Dent Sci 2025 Jan/Mar;28 (1): e4609
Belal AO et al.
Wear of two different attachment systems in implant supported mandibular overdentures: a clinical comparative study
Belal AO et al. Wear of two different attachment systems in implant supported
mandibular overdentures: a clinical comparative study
(Figure 4). All attachment inserts for both
groups were captured on camera under the same
conditions when shooting for documentation
to ensure that replicate experiments can be
accurately repeated. The digital photos were
loaded onto a desktop computer and analyzed
using software (Tucsen Mono Microscope
ISH1000, China) to measure dimensions. Two
perpendicular axes were used in measuring the
inside circumference of the insert (A and B) for
both groups in millimeters (mm) with a maximum
of two decimal places. In addition to two other
axes for the diameter of the central plastic core
(C and D) for the locator group (Figure 5).
The observation period was one year, so all
measurements were repeated 4, 8, and 12 months
after the rst session, and changes in attachment
sizes were noted by tracking the results (Figure 6).
The data were collected, tabulated, and
statistically analyzed using SPSS version 26.0 for
Windows, and the normality test (Shapiro-Wilk)
was used for normality, and the independent
sample t-test was used to compare the two
groups, the level of signicance (p-value) was
set at 0.05.
RESULTS
The stereomicroscope demonstrated the
surface characteristics and internal dimensions of
Novaloc retention inserts and Locator retention
Figure 4. The stereomicroscope (Olympus SZ61, Japan) beside the
camera (10MP Tucsen USB2.0 H series, ISH 1000, China).
Figure 5. Wear measurements using stereomicroscope, (a) Novaloc retention inserts. (b) Locator retention replacement male. A software
program (Tucsen Mono Microscope ISH1000, China) was used to measure the inner circumference of both Novaloc and locator (Axis A, B in
blue color, beside the plastic core of Locator Axis C, D in green color).
USB2.0 H series, ISH 1000, China) attached to
a stereomicroscope (Olympus SZ61, Japan) at
15× magnication. A stereomicroscope was used
to assess wear by measuring internal dimensions
and changes in them during observation periods